Baoquan He [Fri, 18 Apr 2025 22:36:52 +0000 (06:36 +0800)]
mm/vmalloc: optimize function vm_unmap_aliases()
Remove unneeded local variables and replace them with values.
Link: https://lkml.kernel.org/r/20250418223653.243436-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Fri, 18 Apr 2025 22:36:51 +0000 (06:36 +0800)]
mm/vmalloc.c: optimize code in decay_va_pool_node() a little bit
When purge lazily freed vmap areas, VA stored in vn->pool[] will also be
taken away into free vmap tree partially or completely accordingly, that
is done in decay_va_pool_node(). When doing that, for each pool of node,
the whole list is detached from the pool for handling. At this time, that
pool is empty. It's not necessary to update the pool size each time when
one VA is removed and addded into free vmap tree.
Here change code to update the pool size when attaching the pool back.
Link: https://lkml.kernel.org/r/20250418223653.243436-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Fri, 18 Apr 2025 22:36:50 +0000 (06:36 +0800)]
mm/vmalloc.c: find the vmap of vmap_nodes in reverse order
When finding VA in vn->busy, if VA spans several zones and the passed addr
is not the same as va->va_start, we should scan the vn in reverse odrdr
because the starting address of VA must be smaller than the passed addr if
it really resides in the VA.
E.g on a system nr_vmap_nodes=100,
<----va---->
-|-----|-----|-----|-----|-----|-----|-----|-----|-----|-
... n-1 n n+1 n+2 ... 100 0 1
VA resides in node 'n' whereas it spans 'n', 'n+1' and 'n+2'. If passed
addr is within 'n+2', we should try nodes backwards on 'n+1' and 'n', then
succeed very soon.
Meanwhile we still need loop around because VA could spans node from 'n'
to node 100, node 0, node 1.
Anyway, changing to find in reverse order can improve efficiency on many
CPUs system.
Link: https://lkml.kernel.org/r/20250418223653.243436-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Fri, 18 Apr 2025 22:36:49 +0000 (06:36 +0800)]
mm/vmalloc.c: change purge_ndoes as local static variable
Patch series "mm/vmalloc.c: code cleanup and improvements", v2.
These changes were made from code inspection in mm/vmalloc.c.
This patch (of 5):
Static variable 'purge_ndoes' is defined in global scope, while it's only
used in function __purge_vmap_area_lazy(). It mainly serves to avoid
memory allocation repeatedly, especially when NR_CPUS is big.
While a local static variable can also satisfy the demand, and can improve
code readibility. Hence move its definition into
__purge_vmap_area_lazy().
Link: https://lkml.kernel.org/r/20250418223653.243436-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20250418223653.243436-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Christoph Lameter (Ampere) [Mon, 21 Apr 2025 20:58:06 +0000 (13:58 -0700)]
Update Christoph's Email address and make it consistent
Use cl@gentwo.org throughout and remove the old email addresses.
Link: https://lkml.kernel.org/r/8b962f57-4d98-cbb0-cd82-b6ba456733e8@gentwo.org
Signed-off-by: Christoph Lameter <cl@gentwo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Prabhav Kumar Vaish [Sun, 20 Apr 2025 14:04:40 +0000 (19:34 +0530)]
mm: fix typos in comments in mm_init.c
Corrected minor typos in comments:
- 'contigious' -> 'contiguous'
- 'hierarcy' -> 'hierarchy'
This is a non-functional change in comment text only.
Link: https://lkml.kernel.org/r/20250420140440.18817-1-pvkumar5749404@gmail.com
Signed-off-by: Prabhav Kumar Vaish <pvkumar5749404@gmail.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:30 +0000 (12:40 -0700)]
samples/damon: implement a DAMON module for memory tiering
Implement a sample DAMON module that shows how self-tuned DAMON-based
memory tiering can be written. It is a sample since the purpose is to
give an idea about how it can be implemented and perform, rather than be
used on general production setups. Especially, it supports only two tiers
memory setup having only one CPU-attached NUMA node.
[sj@kernel.org: fix wrong DAMON attrs setting]
Link: https://lkml.kernel.org/r/20250510220932.47722-1-sj@kernel.org
[sj@kernel.org: trigger build even if only mtier is enabled]
Link: https://lkml.kernel.org/r/20250426184054.11437-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250420194030.75838-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:29 +0000 (12:40 -0700)]
Docs/ABI/damon: document nid file
Add a description of 'nid' file, which is optionally used for specific
DAMOS quota goal metrics such as node_mem_{used,free}_bp on the DAMON
sysfs ABI document.
Link: https://lkml.kernel.org/r/20250420194030.75838-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:28 +0000 (12:40 -0700)]
Docs/admin-guide/mm/damon/usage: document 'nid' file
Add description of 'nid' file, which is optionally used for specific DAMOS
quota goal metrics such as node_mem_{used,free}_bp on DAMON usage
document.
Link: https://lkml.kernel.org/r/20250420194030.75838-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:27 +0000 (12:40 -0700)]
Docs/mm/damon/design: document node_mem_{used,free}_bp
Add description of DAMOS quota goal metrics for NUMA node utilization on
the DAMON deesign document.
Link: https://lkml.kernel.org/r/20250420194030.75838-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:26 +0000 (12:40 -0700)]
mm/damon/sysfs-schemes: connect damos_quota_goal nid with core layer
DAMON sysfs interface file for DAMOS quota goal's node id argument is not
passed to core layer. Implement the link.
Link: https://lkml.kernel.org/r/20250420194030.75838-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:25 +0000 (12:40 -0700)]
mm/damon/sysfs-schemes: implement file for quota goal nid parameter
DAMOS_QUOTA_NODE_MEM_{USED,FREE}_BP DAMOS quota goal metrics require the
node id parameter. However, there is no DAMON user ABI for setting it.
Implement a DAMON sysfs file for that with name 'nid', under the quota
goal directory.
Link: https://lkml.kernel.org/r/20250420194030.75838-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 20 Apr 2025 19:40:24 +0000 (12:40 -0700)]
mm/damon/core: introduce damos quota goal metrics for memory node utilization
Patch series "mm/damon: auto-tune DAMOS for NUMA setups including tiered
memory".
Utilizing DAMON for memory tiering usually requires manual tuning and/or
tedious controls. Let it self-tune hotness and coldness thresholds for
promotion and demotion aiming high utilization of high memory tiers, by
introducing new DAMOS quota goal metrics representing the used and the
free memory ratios of specific NUMA nodes. And introduce a sample DAMON
module that demonstrates how the new feature can be used for memory
tiering use cases.
Backgrounds
===========
A type of tiered memory system exposes the memory tiers as NUMA nodes. A
straightforward pages placement strategy for such systems is placing
access-hot and cold pages on upper and lower tiers, reespectively,
pursuing higher utilization of upper tiers. Since access temperature can
be dynamic, periodically finding and migrating hot pages and cold pages to
proper tiers (promoting and demoting) is also required. Linux kernel
provides several features for such dynamic and transparent pages
placement.
Page Faults and LRU
-------------------
One widely known way is using NUMA balancing in tiering mode (a.k.a
NUMAB-2) and reclaim-based demotion features. In the setup, NUMAB-2 finds
hot pages using access check-purpose page faults (a.k.a prot_none) and
promote those inside each process' context, until there is no more pages
to promote, or the upper tier is filled up and memory pressure happens.
In the latter case, LRU-based reclaim logic wakes up as a response to the
memory pressure and demotes cold pages to lower tiers in asynchronous
(kswapd) and/or synchronous ways (direct reclaim).
DAMON
-----
Yet another available solution is using DAMOS with migrate_hot and
migrate_cold DAMOS actions for promotions and demotions, respectively. To
make it optimum, users need to specify aggressiveness and access
temperature thresholds for promotions and demotions in a good balance that
results in high utilization of upper tiers. The number of parameters is
not small, and optimum parameter values depend on characteristics of the
underlying hardware and the workload. As a result, it often requires
manual, time consuming and repetitive tuning of the DAMOS schemes for
given workloads and systems combinations.
Self-tuned DAMON-based Memory Tiering
=====================================
To solve such manual tuning problems, DAMOS provides aim-oriented
feedback-driven quotas self-tuning. Using the feature, we design a
self-tuned DAMON-based memory tiering for general multi-tier memory
systems.
For each memory tier node, if it has a lower tier, run a DAMOS scheme that
demotes cold pages of the node, auto-tuning the aggressiveness aiming an
amount of free space of the node. The free space is for keeping the
headroom that avoids significant memory pressure during upper tier memory
usage spike, and promoting hot pages from the lower tier.
For each memory tier node, if it has an upper tier, run a DAMOS scheme
that promotes hot pages of the current node to the upper tier, auto-tuning
the aggressiveness aiming a high utilization ratio of the upper tier. The
target ratio is to ensure higher tiers are utilized as much as possible.
It should match with the headroom for demotion scheme, but have slight
overlap, to ensure promotion and demotion are not entirely stopped.
The aim-oriented aggressiveness auto-tuning of DAMOS is already available.
Hence, to make such tiering solution implementation, only new quota goal
metrics for utilization and free space ratio of specific NUMA node need to
be developed.
Discussions
===========
The design imposes below discussion points.
Expected Behaviors
------------------
The system will let upper tier memory node accommodates as many hot data
as possible. If total amount of the data is less than the top tier
memory's promotion/demotion target utilization, entire data will be just
placed on the top tier. Promotion scheme will do nothing since there is
no data to promote. Demotion scheme will also do nothing since the free
space ratio of the top tier is higher than the goal.
Only if the amount of data is larger than the top tier's utilization
ratio, demotion scheme will demote cold pages and ensure the headroom free
space. Since the promotion and demotion schemes for a single node has
small overlap at their target utilization and free space goals, promotions
and demotions will continue working with a moderate aggressiveness level.
It will keep all data is placed on access hotness under dynamic access
pattern, while minimizing the migration overhead.
In any case, each node will keep headroom free space and as many upper
tiers are utilized as possible.
Ease of Use
-----------
Users still need to set the target utilization and free space ratio, but
it will be easier to set. We argue 99.7 % utilization and 0.5 % free
space ratios can be good default values. It can be easily adjusted based
on desired headroom size of given use case. Users are also still required
to answer the minimum coldness and hotness thresholds. Together with
monitoring intervals auto-tuning[2], DAMON will always show meaningful
amount of hot and cold memory. And DAMOS quota's prioritization mechanism
will make good decision as long as the source information is that
colorful. Hence, users can very naively set the minimum criterias. We
believe any access observation and no access observation within last one
aggregation interval is enough for minimum hot and cold regions criterias.
General Tiered Memory Setup Applicability
-----------------------------------------
The design can be applied to any number of tiers having any performance
characteristics, as long as they can be hierarchical. Hence, applying the
system to different tiered memory system will be straightforward. Note
that this assumes only single CPU NUMA node case. Because today's DAMON
is not aware of which CPU made each access, applying this on systems
having multiple CPU NUMA nodes can be complicated. We are planning to
extend DAMON for the use case, but that's out of the scope of this patch
series.
How To Use
----------
Users can implement the auto-tuned DAMON-based memory tiering using DAMON
sysfs interface. It can be easily done using DAMON user-space tool like
user-space tool. Below evaluation results section shows an example DAMON
user-space tool command for that.
For wider and simpler deployment, having a kernel module that sets up and
run the DAMOS schemes via DAMON kernel API can be useful. The module can
enable the memory tiering at boot time via kernel command line parameter
or at run time with single command. This patch series implements a sample
DAMON kernel module that shows how such module can be implemented.
Comparison To Page Faults and LRU-based Approaches
--------------------------------------------------
The existing page faults based promotion (NUMAB-2) does hot pages
detection and migration in the process context. When there are many pages
to promote, it can block the progress of the application's real works.
DAMOS works in asynchronous worker thread, so it doesn't block the real
works.
NUMAB-2 doesn't provide a way to control aggressiveness of promotion other
than the maximum amount of pages to promote per given time widnow. If hot
pages are found, promotions can happen in the upper-bound speed,
regardless of upper tier's memory pressure. If the maximum speed is not
well set for the given workload, it can result in slow promotion or
unnecessary memory pressure. Self-tuned DAMON-based memory tiering
alleviates the problem by adjusting the speed based on current utilization
of the upper tier.
LRU-based demotion can be triggered in both asynchronous (kswapd) and
synchronous (direct reclaim) ways. Other than the way of finding cold
pages, asynchronous LRU-based demotion and DAMON-based demotion has no big
difference. DAMON-based demotion can make a better balancing with
DAMON-based promotion, though. The LRU-based demotion can do better than
DAMON-based demotion when the tier is having significant memory pressure.
It would be wise to use DAMON-based demotion as a proactive and primary
one, but utilizing LRU-based demotions together as a fast backup solution.
Evaluation
==========
In short, under a setup that requires fast and frequent promotions,
self-tuned DAMON-based memory tiering's hot pages promotion improves
performance about 4.42 %. We believe this shows self-tuned DAMON-based
promotion's effectiveness. Meanwhile, NUMAB-2's hot pages promotion
degrades the performance about 7.34 %. We suspect the degradation is
mostly due to NUMAB-2's synchronous nature that can block the
application's progress, which highlights the advantage of DAMON-based
solution's asynchronous nature.
Note that the test was done with the RFC version of this patch series. We
don't run it again since this patch series got no meaningful change after
the RFC, while the test takes pretty long time.
Setup
-----
Hardware. Use a machine that equips 250 GiB DRAM memory tier and 50 GiB
CXL memory tier. The tiers are exposed as NUMA nodes 0 and 1,
respectively.
Kernel. Use Linux kernel v6.13 that modified as following. Add all DAMON
patches that available on mm tree of 2025-03-15, and this patch series.
Also modify it to ignore mempolicy() system calls, to avoid bad effects
from application's traditional NUMA systems assumed optimizations.
Workload. Use a modified version of Taobench benchmark[3] that available
on DCPerf benchmark suite. It represents an in-memory caching workload.
We set its 'memsize', 'warmup_time', and 'test_time' parameter as 340 GiB,
2,500 seconds and 1,440 seconds. The parameters are chosen to ensure the
workload uses more than DRAM memory tier. Its RSS under the parameter
grows to 270 GiB within the warmup time.
It turned out the workload has a very static access pattrn. Only about 13
% of the RSS is frequently accessed from the beginning to end. Hence
promotion shows no meaningful performance difference regardless of
different design and implementations. We therefore modify the kernel to
periodically demote up to 10 GiB hot pages and promote up to 10 GiB cold
pages once per minute. The intention is to simulate periodic access
pattern changes. The hotness and coldness threshold is very naively set
so that it is more like random access pattern change rather than strict
hot/cold pages exchange. This is why we call the workload as "modified".
It is implemented as two DAMOS schemes each running on an asynchronous
thread. It can be reproduced with DAMON user-space tool like below.
# ./damo start \
--ops paddr --numa_node 0 --monitoring_intervals 10s 200s 200s \
--damos_action migrate_hot 1 \
--damos_quota_interval 60s --damos_quota_space 10G \
--ops paddr --numa_node 1 --monitoring_intervals 10s 200s 200s \
--damos_action migrate_cold 0 \
--damos_quota_interval 60s --damos_quota_space 10G \
--nr_schemes 1 1 --nr_targets 1 1 --nr_ctxs 1 1
System configurations. Use below variant system configurations.
- Baseline. No memory tiering features are turned on.
- Numab_tiering. On the baseline, enable NUMAB-2 and relcaim-based
demotion. In detail, following command is executed:
echo 2 > /proc/sys/kernel/numa_balancing;
echo 1 > /sys/kernel/mm/numa/demotion_enabled;
echo 7 > /proc/sys/vm/zone_reclaim_mode
- DAMON_tiering. On the baseline, utilize self-tuned DAMON-based memory
tiering implementation via DAMON user-space tool. It utilizes two
kernel threads, namely promotion thread and demotion thread. Demotion
thread monitors access pattern of DRAM node using DAMON with
auto-tuned monitoring intervals aiming 4% DAMON-observed access ratio,
and demote coldest pages up to 200 MiB per second aiming 0.5% free
space of DRAM node. Promotion thread monitors CXL node using same
intervals auto-tuning, and promote hot pages in same way but aiming
for 99.7% utilization of DRAM node. Because DAMON provides only
best-effort accuracy, add young page DAMOS filters to allow only and
reject all young pages at promoting and demoting, respectively. It
can be reproduced with DAMON user-space tool like below.
# ./damo start \
--numa_node 0 --monitoring_intervals_goal 4% 3 5ms 10s \
--damos_action migrate_cold 1 --damos_access_rate 0% 0% \
--damos_apply_interval 1s \
--damos_quota_interval 1s --damos_quota_space 200MB \
--damos_quota_goal node_mem_free_bp 0.5% 0 \
--damos_filter reject young \
--numa_node 1 --monitoring_intervals_goal 4% 3 5ms 10s \
--damos_action migrate_hot 0 --damos_access_rate 5% max \
--damos_apply_interval 1s \
--damos_quota_interval 1s --damos_quota_space 200MB \
--damos_quota_goal node_mem_used_bp 99.7% 0 \
--damos_filter allow young \
--damos_nr_quota_goals 1 1 --damos_nr_filters 1 1 \
--nr_targets 1 1 --nr_schemes 1 1 --nr_ctxs 1 1
Measurment Results
------------------
On each system configuration, run the modified version of Taobench and
collect 'score'. 'score' is a metric that calculated and provided by
Taobench to represents the performance of the run on the system. To
handle the measurement errors, repeat the measurement five times. The
results are as below.
Config Score Stdev (%) Normalized
Baseline 1.6165 0.0319 1.9764 1.0000
Numab_tiering 1.4976 0.0452 3.0209 0.9264
DAMON_tiering 1.6881 0.0249 1.4767 1.0443
'Config' column shows the system config of the measurement. 'Score'
column shows the 'score' measurement in average of the five runs on the
system config. 'Stdev' column shows the standsard deviation of the five
measurements of the scores. '(%)' column shows the 'Stdev' to 'Score'
ratio in percentage. Finally, 'Normalized' column shows the averaged
score values of the configs that normalized to that of 'Baseline'.
The periodic hot pages demotion and cold pages promotion that was
conducted to simulate dynamic access pattern was started from the
beginning of the workload. It resulted in the DRAM tier utilization
always under the watermark, and hence no real demotion was happened for
all test runs. This means the above results show no difference between
LRU-based and DAMON-based demotions. Only difference between NUMAB-2 and
DAMON-based promotions are represented on the results.
Numab_tiering config degraded the performance about 7.36 %. We suspect
this happened because NUMAB-2's synchronous promotion was blocking the
Taobench's real work progress.
DAMON_tiering config improved the performance about 4.43 %. We believe
this shows effectiveness of DAMON-based promotion that didn't block
Taobench's real work progress due to its asynchronous nature. Also this
means DAMON's monitoring results are accurate enough to provide visible
amount of improvement.
Evaluation Limitations
----------------------
As mentioned above, this evaluation shows only comparison of promotion
mechanisms. DAMON-based tiering is recommended to be used together with
reclaim-based demotion as a faster backup under significant memory
pressure, though.
From some perspective, the modified version of Taobench may seems making
the picture distorted too much. It would be better to evaluate with more
realistic workload, or more finely tuned micro benchmarks.
Patch Sequence
==============
The first patch (patch 1) implements two new quota goal metrics on core
layer and expose it to DAMON core kernel API. The second and third ones
(patches 2 and 3) further link it to DAMON sysfs interface. Three
following patches (patches 4-6) document the new feature and sysfs file on
design, usage, and ABI documents. The final one (patch 7) implements a
working version of a self-tuned DAMON-based memory tiering solution in an
incomplete but easy to understand form as a kernel module under
samples/damon/ directory.
References
==========
[1] https://lore.kernel.org/
20231112195602.61525-1-sj@kernel.org/
[2] https://lore.kernel.org/
20250303221726.484227-1-sj@kernel.org
[3] https://github.com/facebookresearch/DCPerf/blob/main/packages/tao_bench/README.md
This patch (of 7):
Used and free space ratios for specific NUMA nodes can be useful inputs
for NUMA-specific DAMOS schemes' aggressiveness self-tuning feedback loop.
Implement DAMOS quota goal metrics for such self-tuned schemes.
Link: https://lkml.kernel.org/r/20250420194030.75838-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250420194030.75838-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rakie Kim [Thu, 17 Apr 2025 07:28:37 +0000 (16:28 +0900)]
mm/mempolicy: support memory hotplug in weighted interleave
The weighted interleave policy distributes page allocations across
multiple NUMA nodes based on their performance weight, thereby improving
memory bandwidth utilization. The weight values for each node are
configured through sysfs.
Previously, sysfs entries for configuring weighted interleave were created
for all possible nodes (N_POSSIBLE) at initialization, including nodes
that might not have memory. However, not all nodes in N_POSSIBLE are
usable at runtime, as some may remain memoryless or offline. This led to
sysfs entries being created for unusable nodes, causing potential
misconfiguration issues.
To address this issue, this patch modifies the sysfs creation logic to:
1) Limit sysfs entries to nodes that are online and have memory, avoiding
the creation of sysfs entries for nodes that cannot be used.
2) Support memory hotplug by dynamically adding and removing sysfs entries
based on whether a node transitions into or out of the N_MEMORY state.
Additionally, the patch ensures that sysfs attributes are properly managed
when nodes go offline, preventing stale or redundant entries from
persisting in the system.
By making these changes, the weighted interleave policy now manages its
sysfs entries more efficiently, ensuring that only relevant nodes are
considered for interleaving, and dynamically adapting to memory hotplug
events.
[dan.carpenter@linaro.org: fix error code in sysfs_wi_node_add()]
Link: https://lkml.kernel.org/r/aBjL7Bwc0QBzgajK@stanley.mountain
Link: https://lkml.kernel.org/r/20250417072839.711-4-rakie.kim@sk.com
Co-developed-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Co-developed-by: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rakie Kim [Thu, 17 Apr 2025 07:28:36 +0000 (16:28 +0900)]
mm/mempolicy: prepare weighted interleave sysfs for memory hotplug
Previously, the weighted interleave sysfs structure was statically managed
during initialization. This prevented new nodes from being recognized
when memory hotplug events occurred, limiting the ability to update or
extend sysfs entries dynamically at runtime.
To address this, this patch refactors the sysfs infrastructure and
encapsulates it within a new structure, `sysfs_wi_group`, which holds both
the kobject and an array of node attribute pointers.
By allocating this group structure globally, the per-node sysfs attributes
can be managed beyond initialization time, enabling external modules to
insert or remove node entries in response to events such as memory hotplug
or node online/offline transitions.
Instead of allocating all per-node sysfs attributes at once, the
initialization path now uses the existing sysfs_wi_node_add() and
sysfs_wi_node_delete() helpers. This refactoring makes it possible to
modularly manage per-node sysfs entries and ensures the infrastructure is
ready for runtime extension.
Link: https://lkml.kernel.org/r/20250417072839.711-3-rakie.kim@sk.com
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rakie Kim [Thu, 17 Apr 2025 07:28:35 +0000 (16:28 +0900)]
mm/mempolicy: fix memory leaks in weighted interleave sysfs
Patch series "Enhance sysfs handling for memory hotplug in weighted
interleave", v9.
The following patch series enhances the weighted interleave policy in the
memory management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug support.
This patch (of 3):
Memory leaks occurred when removing sysfs attributes for weighted
interleave. Improper kobject deallocation led to unreleased memory when
initialization failed or when nodes were removed.
The risk of leak is low because it only appears to trigger if setup
fails. Setup only fails due to -ENOMEM which is unlikely to happen
from a late_initcall() when memory pressure is low.
This patch resolves the issue by replacing unnecessary `kfree()` calls
with proper `kobject_del()` and `kobject_put()` sequences, ensuring
correct teardown and preventing memory leaks.
By explicitly calling `kobject_del()` before `kobject_put()`, the release
function is now invoked safely, and internal sysfs state is correctly
cleaned up. This guarantees that the memory associated with the kobject
is fully released and avoids resource leaks, thereby improving system
stability.
Additionally, sysfs_remove_file() is no longer called from the release
function to avoid accessing invalid sysfs state after kobject_del(). All
attribute removals are now done before kobject_del(), preventing WARN_ON()
in kernfs and ensuring safe and consistent cleanup of sysfs entries.
Link: https://lkml.kernel.org/r/20250417072839.711-1-rakie.kim@sk.com
Link: https://lkml.kernel.org/r/20250417072839.711-2-rakie.kim@sk.com
Fixes:
dce41f5ae253 ("mm/mempolicy: implement the sysfs-based weighted_interleave interface")
Signed-off-by: Rakie Kim <rakie.kim@sk.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Chen Ni [Thu, 17 Apr 2025 08:43:30 +0000 (16:43 +0800)]
mm: memcontrol: remove unnecessary NULL check before free_percpu()
free_percpu() checks for NULL pointers internally. Remove unneeded NULL
check here.
Link: https://lkml.kernel.org/r/20250417084330.937380-1-nichen@iscas.ac.cn
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Thu, 17 Apr 2025 16:12:16 +0000 (18:12 +0200)]
vmalloc: align nr_vmalloc_pages and vmap_lazy_nr
Currently both atomics share one cache-line:
<snip>
...
ffffffff83eab400 b vmap_lazy_nr
ffffffff83eab408 b nr_vmalloc_pages
...
<snip>
those are global variables and they are only 8 bytes apart. Since they
are modified by different threads this causes a false sharing. This can
lead to a performance drop due to unnecessary cache invalidations.
After this patch it is aligned to a cache line boundary:
<snip>
...
ffffffff8260a600 d vmap_lazy_nr
ffffffff8260a640 d nr_vmalloc_pages
...
<snip>
Link: https://lkml.kernel.org/r/20250417161216.88318-4-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Thu, 17 Apr 2025 16:12:15 +0000 (18:12 +0200)]
MAINTAINERS: add test_vmalloc.c to VMALLOC section
A vmalloc subsystem includes "lib/test_vmalloc.c" test suite. Add an "F:"
entry under VMALLOC section to track this file as part of the subsystem.
Link: https://lkml.kernel.org/r/20250417161216.88318-3-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Thu, 17 Apr 2025 16:12:14 +0000 (18:12 +0200)]
lib/test_vmalloc.c: allow built-in execution
Remove the dependency on module loading ("m") for the vmalloc test suite,
enabling it to be built directly into the kernel, so both ("=m") and
("=y") are supported.
Motivation:
- Faster debugging/testing of vmalloc code;
- It allows to configure the test via kernel-boot parameters.
Configuration example:
test_vmalloc.nr_threads=64
test_vmalloc.run_test_mask=7
test_vmalloc.sequential_test_order=1
Link: https://lkml.kernel.org/r/20250417161216.88318-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Thu, 17 Apr 2025 16:12:13 +0000 (18:12 +0200)]
lib/test_vmalloc.c: replace RWSEM to SRCU for setup
The test has the initialization step during which threads are created. To
prevent the workers from starting prematurely a write lock was previously
used by the main setup thread, while each worker would block on a read
lock.
Replace this RWSEM based synchronization with a simpler SRCU based
approach. Which does two basic steps:
- Main thread wraps the setup phase in an SRCU read-side critical
section. Pair of srcu_read_lock()/srcu_read_unlock().
- Each worker calls synchronize_srcu() on entry, ensuring it waits for
the initialization phase to be completed.
This patch eliminates the need for down_read()/up_read() and
down_write()/up_write() pairs thus simplifying the logic and improving
clarity.
[urezki@gmail.com: fix compile error with CONFIG_TINY_RCU]
Link: https://lkml.kernel.org/r/20250420142029.103169-1-urezki@gmail.com
Link: https://lkml.kernel.org/r/20250417161216.88318-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Adrian Huang <ahuang12@lenovo.com>
Tested-by: Adrian Huang <ahuang12@lenovo.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sergey Senozhatsky [Wed, 16 Apr 2025 04:27:59 +0000 (13:27 +0900)]
Documentation: zram: update IDLE pages tracking documentation
Move IDLE pages tracking into a separate chapter because there are
multiple features that use (or depend on) it either in built-in variant
("mark all") or in extended variant (ac-time tracking).
In addition, recompression doesn't require memory tracking to be enabled
in order to be able to perform idle recompression.
Link: https://lkml.kernel.org/r/20250416042833.3858827-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Shin Kawamura <kawasin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dev Jain [Wed, 16 Apr 2025 05:30:48 +0000 (11:00 +0530)]
mempolicy: optimize queue_folios_pte_range by PTE batching
After the check for queue_folio_required(), the code only cares about the
folio in the for loop, i.e the PTEs are redundant. Therefore, optimize
this loop by skipping over a PTE batch mapping the same folio.
With a test program migrating pages of the calling process, which includes
a mapped VMA of size 4GB with pte-mapped large folios of order-9, and
migrating once back and forth node-0 and node-1, the average execution
time reduces from 7.5 to 4 seconds, giving an approx 47% speedup.
Link: https://lkml.kernel.org/r/20250416053048.96479-1-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lorenzo Stoakes [Wed, 16 Apr 2025 10:38:36 +0000 (11:38 +0100)]
mm: move mmap/vma locking logic into specific files
Currently the VMA and mmap locking logic is entangled in two of the most
overwrought files in mm - include/linux/mm.h and mm/memory.c. Separate
this logic out so we can more easily make changes and create an
appropriate MAINTAINERS entry that spans only the logic relating to
locking.
This should have no functional change. Care is taken to avoid dependency
loops, we must regrettably keep release_fault_lock() and
assert_fault_locked() in mm.h as a result due to the dependence on the
vm_fault type.
Additionally we must declare rcuwait_wake_up() manually to avoid a
dependency cycle on linux/rcuwait.h.
Additionally move the nommu implementatino of lock_mm_and_find_vma() to
mmap_lock.c so everything lock-related is in one place.
Link: https://lkml.kernel.org/r/bec6c8e29fa8de9267a811a10b1bdae355d67ed4.1744799282.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Shakeel Butt [Wed, 16 Apr 2025 18:02:29 +0000 (11:02 -0700)]
memcg: multi-memcg percpu charge cache
Memory cgroup accounting is expensive and to reduce the cost, the kernel
maintains per-cpu charge cache for a single memcg. So, if a charge
request comes for a different memcg, the kernel will flush the old memcg's
charge cache and then charge the newer memcg a fixed amount (64 pages),
subtracts the charge request amount and stores the remaining in the
per-cpu charge cache for the newer memcg.
This mechanism is based on the assumption that the kernel, for locality,
keep a process on a CPU for long period of time and most of the charge
requests from that process will be served by that CPU's local charge
cache.
However this assumption breaks down for incoming network traffic in a
multi-tenant machine. We are in the process of running multiple workloads
on a single machine and if such workloads are network heavy, we are seeing
very high network memory accounting cost. We have observed multiple CPUs
spending almost 100% of their time in net_rx_action and almost all of that
time is spent in memcg accounting of the network traffic.
More precisely, net_rx_action is serving packets from multiple workloads
and is observing/serving mix of packets of these workloads. The memcg
switch of per-cpu cache is very expensive and we are observing a lot of
memcg switches on the machine. Almost all the time is being spent on
charging new memcg and flushing older memcg cache. So, definitely we need
per-cpu cache that support multiple memcgs for this scenario.
This patch implements a simple (and dumb) multiple memcg percpu charge
cache. Actually we started with more sophisticated LRU based approach but
the dumb one was always better than the sophisticated one by 1% to 3%, so
going with the simple approach.
Some of the design choices are:
1. Fit all caches memcgs in a single cacheline.
2. The cache array can be mix of empty slots or memcg charged slots, so
the kernel has to traverse the full array.
3. The cache drain from the reclaim will drain all cached memcgs to keep
things simple.
To evaluate the impact of this optimization, on a 72 CPUs machine, we ran
the following workload where each netperf client runs in a different
cgroup. The next-
20250415 kernel is used as base.
$ netserver -6
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
number of clients | Without patch | With patch
6 | 42584.1 Mbps | 48603.4 Mbps (14.13% improvement)
12 | 30617.1 Mbps | 47919.7 Mbps (56.51% improvement)
18 | 25305.2 Mbps | 45497.3 Mbps (79.79% improvement)
24 | 20104.1 Mbps | 37907.7 Mbps (88.55% improvement)
30 | 14702.4 Mbps | 30746.5 Mbps (109.12% improvement)
36 | 10801.5 Mbps | 26476.3 Mbps (145.11% improvement)
The results show drastic improvement for network intensive workloads.
[shakeel.butt@linux.dev: add BUILD_BUG_ON() for MEMCG_CHARGE_BATCH]
Link: https://lkml.kernel.org/r/rlsgeosg3j7v5nihhbxxxbv3xfy4ejvigihj7lkkbt3n6imyne@2apxx2jm2e57
[shakeel.butt@linux.dev: simplify refill_stock]
Link: https://lkml.kernel.org/r/as5cdsm4lraxupg3t6onep2ixql72za25hvd4x334dsoyo4apr@zyzl4vkuevuv
[hughd@google.com: it's better to stock nr_pages than the uninitialized stock_pages]
Link: https://lkml.kernel.org/r/d542d18f-1caa-6fea-e2c3-3555c87bcf64@google.com
[shakeel.butt@linux.dev: add comment per Michal and use DEFINE_PER_CPU_ALIGNED instead of DEFINE_PER_CPU per Vlastimil]
Link: https://lkml.kernel.org/r/dieeei3squ2gcnqxdjayvxbvzldr266rhnvtl3vjzsqevxkevf@ckui5vjzl2qg
Link: https://lkml.kernel.org/r/20250416180229.2902751-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Eric Dumaze <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fan Ni [Wed, 16 Apr 2025 20:12:15 +0000 (13:12 -0700)]
mm: convert free_page_and_swap_cache() to free_folio_and_swap_cache()
free_page_and_swap_cache() takes a struct page pointer as input parameter,
but it will immediately convert it to folio and all operations following
within use folio instead of page. It makes more sense to pass in folio
directly.
Convert free_page_and_swap_cache() to free_folio_and_swap_cache() to
consume folio directly.
Link: https://lkml.kernel.org/r/20250416201720.41678-1-nifan.cxl@gmail.com
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
gaoxu [Sat, 12 Apr 2025 09:27:24 +0000 (09:27 +0000)]
mm: add nr_free_highatomic in show_free_areas
commit
c928807f6f6b6("mm/page_alloc: keep track of free highatomic")
adds a new variable nr_free_highatomic, which is useful for analyzing low
mem issues. add nr_free_highatomic in show_free_areas.
Signed-off-by: gao xu <gaoxu2@honor.com>
Link: https://lkml.kernel.org/r/d92eeff74f7a4578a14ac777cfe3603a@honor.com
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Hao Ge [Thu, 17 Apr 2025 09:24:22 +0000 (17:24 +0800)]
mm/vmscan: modify the assignment logic of the scan and total_scan variables
The scan and total_scan variables can be initialized to 0 when they are
defined, replacing the separate assignment statements.
Link: https://lkml.kernel.org/r/20250417092422.1333620-1-hao.ge@linux.dev
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Acked-by: Dev Jain <dev.jain@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Enze Li [Fri, 11 Apr 2025 07:38:00 +0000 (15:38 +0800)]
samples/damon/prcl: fix a comment typo
This patch just fixes a typo in the comment.
Link: https://lkml.kernel.org/r/20250411073800.1444481-1-lienze@kylinos.cn
Signed-off-by: Enze Li <lienze@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Thu, 10 Apr 2025 03:57:17 +0000 (11:57 +0800)]
mm/gup: clean up codes in fault_in_xxx() functions
The code style in fault_in_readable() and fault_in_writable() is a little
inconsistent with fault_in_safe_writeable(). In fault_in_readable() and
fault_in_writable(), it uses 'uaddr' passed in as loop cursor. While in
fault_in_safe_writeable(), local variable 'start' is used as loop cursor.
This may mislead people when reading code or making change in these codes.
Here define explicit loop cursor and use for loop to simplify codes in
these three functions. These cleanup can make them be consistent in code
style and improve readability.
[bhe@redhat.com: address minor concerns from David]
Link: https://lkml.kernel.org/r/Z/sbv3EmLXWgEE7+@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20250410035717.473207-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Thu, 10 Apr 2025 03:57:16 +0000 (11:57 +0800)]
mm/gup: remove gup_fast_pgd_leaf() and clean up the relevant codes
In the current kernel, only pud huge page is supported in some
architectures. P4d and pgd huge pages haven't been supported yet. And in
mm/gup.c, there's no pgd huge page handling in the follow_page_mask() code
path. Hence it doesn't make sense to only have gup_fast_pgd_leaf() in
gup_fast code path.
Here remove gup_fast_pgd_leaf() and clean up the relevant codes.
Link: https://lkml.kernel.org/r/20250410035717.473207-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baoquan He [Thu, 10 Apr 2025 03:57:15 +0000 (11:57 +0800)]
mm/gup: remove unneeded checking in follow_page_pte()
Patch series "mm/gup: Minor fix, cleanup and improvements", v4.
These were made from code inspection in mm/gup.c.
This patch (of 3):
In __get_user_pages(), it will traverse page table and take a reference to
the page the given user address corresponds to if GUP_GET or GUP_PIN is
set. However, it's not supported both GUP_GET and GUP_PIN are set. Even
though this check need be done, it should be done earlier, but not doing
it till entering into follow_page_pte() and failed.
Furthermore, this checking has been done in is_valid_gup_args() and all
external users of __get_user_pages() will call is_valid_gup_args() to
catch the illegal setting. We don't need to worry about internal users of
__get_user_pages() because the gup_flags are set by MM code correctly.
Here remove the checking in follow_page_pte(), and add VM_WARN_ON_ONCE()
to catch the possible exceptional setting just in case.
And also change the VM_BUG_ON to VM_WARN_ON_ONCE() for checking (!!pages
!= !!(gup_flags & (FOLL_GET | FOLL_PIN))) because the checking has been
done in is_valid_gup_args() for external users of __get_user_pages().
Link: https://lkml.kernel.org/r/20250410035717.473207-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20250410035717.473207-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Yanjun.Zhu <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oscar Salvador [Fri, 11 Apr 2025 13:23:59 +0000 (15:23 +0200)]
mm,hugetlb: allocate frozen pages in alloc_buddy_hugetlb_folio
alloc_buddy_hugetlb_folio() allocates a rmappable folio, then strips the
rmappable part and freezes it. We can simplify all that by allocating
frozen pages directly.
Link: https://lkml.kernel.org/r/20250411132359.312708-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Tue, 15 Apr 2025 11:26:46 +0000 (13:26 +0200)]
vmalloc: use atomic_long_add_return_relaxed()
Switch from the atomic_long_add_return() to its relaxed version.
We do not need a full memory barrier or any memory ordering during
increasing the "vmap_lazy_nr" variable. What we only need is to do it
atomically. This is what atomic_long_add_return_relaxed() guarantees.
AARCH64:
<snip>
Default:
40ec:
d34cfe94 lsr x20, x20, #12
40f0:
14000044 b 4200 <free_vmap_area_noflush+0x19c>
40f4:
94000000 bl 0 <__sanitizer_cov_trace_pc>
40f8:
90000000 adrp x0, 0 <__traceiter_alloc_vmap_area>
40fc:
91000000 add x0, x0, #0x0
4100:
f8f40016 ldaddal x20, x22, [x0]
4104:
8b160296 add x22, x20, x22
Relaxed:
40ec:
d34cfe94 lsr x20, x20, #12
40f0:
14000044 b 4200 <free_vmap_area_noflush+0x19c>
40f4:
94000000 bl 0 <__sanitizer_cov_trace_pc>
40f8:
90000000 adrp x0, 0 <__traceiter_alloc_vmap_area>
40fc:
91000000 add x0, x0, #0x0
4100:
f8340016 ldadd x20, x22, [x0]
4104:
8b160296 add x22, x20, x22
<snip>
Link: https://lkml.kernel.org/r/20250415112646.113091-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christop Hellwig <hch@infradead.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oscar Salvador [Tue, 15 Apr 2025 12:15:03 +0000 (14:15 +0200)]
mm, hugetlb: avoid passing a null nodemask when there is mbind policy
Before trying to allocate a page, gather_surplus_pages() sets up a
nodemask for the nodes we can allocate from, but instead of passing the
nodemask down the road to the page allocator, it iterates over the nodes
within that nodemask right there, meaning that the page allocator will
receive a preferred_nid and a null nodemask.
This is a problem when using a memory policy, because it might be that the
page allocator ends up using a node as a fallback which is not represented
in the policy.
Avoid that by passing the nodemask directly to the page allocator, so it
can filter out fallback nodes that are not part of the nodemask.
Link: https://lkml.kernel.org/r/20250415121503.376811-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Enze Li [Fri, 11 Apr 2025 02:43:32 +0000 (10:43 +0800)]
selftests/damon: remove the remaining test scripts for DAMON debugfs interface
DAMON has dropped debugfs support; therefore, remove these unused scripts.
Link: https://lkml.kernel.org/r/20250411024332.1373861-1-enze.li@linux.dev
Fixes:
5ec4333b1967 ("mm/damon: remove DAMON debugfs interface")
Signed-off-by: Enze Li <lienze@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Shakeel Butt [Thu, 10 Apr 2025 02:57:52 +0000 (19:57 -0700)]
memcg: optimize memcg_rstat_updated
Currently the kernel maintains the stats updates per-memcg which is needed
to implement stats flushing threshold. On the update side, the update is
added to the per-cpu per-memcg update of the given memcg and all of its
ancestors. However when the given memcg has passed the flushing
threshold, all of its ancestors should have passed the threshold as well.
There is no need to traverse up the memcg tree to maintain the stats
updates.
Perf profile collected from our fleet shows that memcg_rstat_updated is
one of the most expensive memcg function i.e. a lot of cumulative CPU is
being spent on it. So, even small micro optimizations matter a lot. This
patch is microbenchmarked with multiple instances of netperf on a single
machine with locally running netserver and we see couple of percentage of
improvement.
Link: https://lkml.kernel.org/r/20250410025752.92159-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Donet Tom [Thu, 10 Apr 2025 10:07:48 +0000 (05:07 -0500)]
selftests/mm: restore default nr_hugepages value during cleanup in hugetlb_reparenting_test.sh
During cleanup, the value of /proc/sys/vm/nr_hugepages is currently being
set to 0. At the end of the test, if all tests pass, the original
nr_hugepages value is restored. However, if any test fails, it remains
set to 0.
With this patch, we ensure that the original nr_hugepages value is
restored during cleanup, regardless of whether the test passes or fails.
Link: https://lkml.kernel.org/r/20250410100748.2310-1-donettom@linux.ibm.com
Fixes:
29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Cc: Li Wang <liwang@redhat.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:46 +0000 (19:14 +0000)]
maple_tree: reorder mas->store_type case statements
Move the unlikely case that mas->store_type is invalid to be the last
evaluated case and put liklier cases higher up.
Link: https://lkml.kernel.org/r/20250410191446.2474640-7-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam R. Howlett <liam.howlett@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:45 +0000 (19:14 +0000)]
maple_tree: add sufficient height
In order to support rebalancing and spanning stores using less than the
worst case number of nodes, we need to track more than just the vacant
height. Using only vacant height to reduce the worst case maple node
allocation count can lead to a shortcoming of nodes in the following
scenarios.
For rebalancing writes, when a leaf node becomes insufficient, it may be
combined with a sibling into a single node. This means that the parent
node which has entries for this children will lose one entry. If this
parent node was just meeting the minimum entries, losing one entry will
now cause this parent node to be insufficient. This leads to a cascading
operation of rebalancing at different levels and can lead to more node
allocations than simply using vacant height can return.
For spanning writes, a similar situation occurs. At the location at which
a spanning write is detected, the number of ancestor nodes may similarly
need to rebalanced into a smaller number of nodes and the same cascading
situation could occur.
To use less than the full height of the tree for the number of
allocations, we also need to track the height at which a non-leaf node
cannot become insufficient. This means even if a rebalance occurs to a
child of this node, it currently has enough entries that it can lose one
without any further action. This field is stored in the maple write state
as sufficient height. In mas_prealloc_calc() when figuring out how many
nodes to allocate, we check if the vacant node is lower in the tree than a
sufficient node (has a larger value). If it is, we cannot use the vacant
height and must use the difference in the height and sufficient height as
the basis for the number of nodes needed.
An off by one bug was also discovered in mast_overflow() where it is using
>= rather than >. This caused extra iterations of the
mas_spanning_rebalance() loop and lead to unneeded allocations. A test is
also added to check the number of allocations is correct.
Link: https://lkml.kernel.org/r/20250410191446.2474640-6-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:44 +0000 (19:14 +0000)]
maple_tree: break on convergence in mas_spanning_rebalance()
This allows support for using the vacant height to calculate the worst
case number of nodes needed for wr_rebalance operation.
mas_spanning_rebalance() was seen to perform unnecessary node allocations.
We can reduce allocations by breaking early during the rebalancing loop
once we realize that we have ascended to a common ancestor.
Link: https://lkml.kernel.org/r/20250410191446.2474640-5-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Liam Howlett <liam.howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:43 +0000 (19:14 +0000)]
maple_tree: use vacant nodes to reduce worst case allocations
In order to determine the store type for a maple tree operation, a walk of
the tree is done through mas_wr_walk(). This function descends the tree
until a spanning write is detected or we reach a leaf node. While
descending, keep track of the height at which we encounter a node with
available space. This is done by checking if mas->end is less than the
number of slots a given node type can fit.
Now that the height of the vacant node is tracked, we can use the
difference between the height of the tree and the height of the vacant
node to know how many levels we will have to propagate creating new nodes.
Update mas_prealloc_calc() to consider the vacant height and reduce the
number of worst-case allocations.
Rebalancing and spanning stores are not supported and fall back to using
the full height of the tree for allocations.
Update preallocation testing assertions to take into account vacant
height.
Link: https://lkml.kernel.org/r/20250410191446.2474640-4-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:42 +0000 (19:14 +0000)]
maple_tree: use height and depth consistently
For the maple tree, the root node is defined to have a depth of 0 with a
height of 1. Each level down from the node, these values are incremented
by 1. Various code paths define a root with depth 1 which is inconsisent
with the definition. Modify the code to be consistent with this
definition.
In mas_spanning_rebalance(), l_mas.depth was being used to track the
height based on the number of iterations done in the main loop. This
information was then used in mas_put_in_tree() to set the height. Rather
than overload the l_mas.depth field to track height, simply keep track of
height in the local variable new_height and directly pass this to
mas_wmb_replace() which will be passed into mas_put_in_tree(). This
allows up to remove writes to l_mas.depth.
Link: https://lkml.kernel.org/r/20250410191446.2474640-3-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sidhartha Kumar [Thu, 10 Apr 2025 19:14:41 +0000 (19:14 +0000)]
maple_tree: convert mas_prealloc_calc() to take in a maple write state
Patch series "Track node vacancy to reduce worst case allocation counts", v5.
================ overview ========================
Currently, the maple tree preallocates the worst case number of nodes for
given store type by taking into account the whole height of the tree.
This comes from a worst case scenario of every node in the tree being full
and having to propagate node allocation upwards until we reach the root of
the tree. This can be optimized if there are vacancies in nodes that are
at a lower depth than the root node. This series implements tracking the
level at which there is a vacant node so we only need to allocate until
this level is reached, rather than always using the full height of the
tree. The ma_wr_state struct is modified to add a field which keeps track
of the vacant height and is updated during walks of the tree. This value
is then read in mas_prealloc_calc() when we decide how many nodes to
allocate.
For rebalancing and spanning stores, we also need to track the lowest
height at which a node has 1 more entry than the minimum sufficient number
of entries. This is because rebalancing can cause a parent node to become
insufficient which results in further node allocations. In this case, we
need to use the sufficient height as the worst case rather than the vacant
height.
patch 1-2: preparatory patches
patch 3: implement vacant height tracking + update the tests
patch 4: support vacant height tracking for rebalancing writes
patch 5: implement sufficient height tracking
patch 6: reorder switch case statements
================ results =========================
Bpftrace was used to profile the allocation path for requesting new maple
nodes while running stress-ng mmap 120s. The histograms below represent
requests to kmem_cache_alloc_bulk() and show the count argument. This
represnts how many maple nodes the caller is requesting in
kmem_cache_alloc_bulk()
command: stress-ng --mmap 4 --timeout 120
mm-unstable
@bulk_alloc_req:
[3, 4) 4 | |
[4, 5) 54170 |@ |
[5, 6) 0 | |
[6, 7) 893057 |@@@@@@@@@@@@@@@@@@@@ |
[7, 8) 4 | |
[8, 9)
2230287 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[9, 10) 55811 |@ |
[10, 11) 77834 |@ |
[11, 12) 0 | |
[12, 13)
1368684 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[13, 14) 0 | |
[14, 15) 0 | |
[15, 16) 367197 |@@@@@@@@ |
@maple_node_total: 46,630,160
@total_vmas:
46184591
mm-unstable + this series
@bulk_alloc_req:
[2, 3) 198 | |
[3, 4) 4 | |
[4, 5) 43 | |
[5, 6) 0 | |
[6, 7)
1069503 |@@@@@@@@@@@@@@@@@@@@@ |
[7, 8) 4 | |
[8, 9)
2597268 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[9, 10) 472191 |@@@@@@@@@ |
[10, 11) 191904 |@@@ |
[11, 12) 0 | |
[12, 13) 247316 |@@@@ |
[13, 14) 0 | |
[14, 15) 0 | |
[15, 16) 98769 |@ |
@maple_node_total: 37,813,856
@total_vmas:
43493287
This represents a ~19% reduction in the number of bulk maple nodes allocated.
For more reproducible results, a historgram of the return value of
mas_prealloc_calc() is displayed while running the maple_tree_tests whcih
have a deterministic store pattern
mas_prealloc_calc() return value mm-unstable
1 : (12068)
3 : (11836)
5 : ***** (271192)
7 : ************************************************** (
2329329)
9 : *********** (534186)
10 : (435)
11 : *************** (704306)
13 : ******** (409781)
mas_prealloc_calc() return value mm-unstable + this series
1 : (12070)
3 : ************************************************** (
3548777)
5 : ******** (633458)
7 : (65081)
9 : (11224)
10 : (341)
11 : (2973)
13 : (68)
do_mmap latency was also measured for regressions:
command: stress-ng --mmap 4 --timeout 120
mm-unstable:
avg = 7162 nsecs, total:
16101821292 nsecs, count:
2248034
mm-unstable + this series:
avg = 6689 nsecs, total:
15135391764 nsecs, count:
2262726
stress-ng --mmap4 --timeout 120
with vacant_height:
stress-ng: info: [257]
21526312 Maple Tree Read 0.176 M/sec
stress-ng: info: [257]
339979348 Maple Tree Write 2.774 M/sec
without vacant_height:
stress-ng: info: [8228]
20968900 Maple Tree Read 0.171 M/sec
stress-ng: info: [8228]
312214648 Maple Tree Write 2.547 M/sec
This represents an increase of ~3% read throughput and ~9% increase in
write throughput.
This patch (of 6):
In a subsequent patch, mas_prealloc_calc() will need to access fields only
in the ma_wr_state. Convert the function to take in a ma_wr_state and
modify all callers. There is no functional change.
Link: https://lkml.kernel.org/r/20250410191446.2474640-1-sidhartha.kumar@oracle.com
Link: https://lkml.kernel.org/r/20250410191446.2474640-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Thu, 10 Apr 2025 00:00:22 +0000 (17:00 -0700)]
mm/madvise: batch tlb flushes for MADV_DONTNEED[_LOCKED]
MADV_DONTNEED[_LOCKED] handling for [process_]madvise() flushes tlb for
each vma of each address range. Update the logic to do tlb flushes in a
batched way. Initialize an mmu_gather object from do_madvise() and
vector_madvise(), which are the entry level functions for
[process_]madvise(), respectively. And pass those objects to the function
for per-vma work, via madvise_behavior struct. Make the per-vma logic not
flushes tlb on their own but just saves the tlb entries to the received
mmu_gather object. For this internal logic change, make
zap_page_range_single_batched() non-static and use it directly from
madvise_dontneed_single_vma(). Finally, the entry level functions flush
the tlb entries that gathered for the entire user request, at once.
Link: https://lkml.kernel.org/r/20250410000022.1901-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Thu, 10 Apr 2025 00:00:21 +0000 (17:00 -0700)]
mm/memory: split non-tlb flushing part from zap_page_range_single()
Some of zap_page_range_single() callers such as [process_]madvise() with
MADV_DONTNEED[_LOCKED] cannot batch tlb flushes because
zap_page_range_single() flushes tlb for each invocation. Split out the
body of zap_page_range_single() except mmu_gather object initialization
and gathered tlb entries flushing for such batched tlb flushing usage.
To avoid hugetlb pages allocation failures from concurrent page faults,
the tlb flush should be done before hugetlb faults unlocking, though. Do
the flush and the unlock inside the split out function in the order for
hugetlb vma case. Refer to commit
2820b0f09be9 ("hugetlbfs: close race
between MADV_DONTNEED and page fault") for more details about the
concurrent faults' page allocation failure problem.
Link: https://lkml.kernel.org/r/20250410000022.1901-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Thu, 10 Apr 2025 00:00:20 +0000 (17:00 -0700)]
mm/madvise: batch tlb flushes for MADV_FREE
MADV_FREE handling for [process_]madvise() flushes tlb for each vma of
each address range. Update the logic to do tlb flushes in a batched way.
Initialize an mmu_gather object from do_madvise() and vector_madvise(),
which are the entry level functions for [process_]madvise(), respectively.
And pass those objects to the function for per-vma work, via
madvise_behavior struct. Make the per-vma logic not flushes tlb on their
own but just saves the tlb entries to the received mmu_gather object.
Finally, the entry level functions flush the tlb entries that gathered for
the entire user request, at once.
Link: https://lkml.kernel.org/r/20250410000022.1901-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Thu, 10 Apr 2025 00:00:19 +0000 (17:00 -0700)]
mm/madvise: define and use madvise_behavior struct for madvise_do_behavior()
Patch series "mm/madvise: batch tlb flushes for MADV_DONTNEED and
MADV_FREE", v3.
When process_madvise() is called to do MADV_DONTNEED[_LOCKED] or MADV_FREE
with multiple address ranges, tlb flushes happen for each of the given
address ranges. Because such tlb flushes are for the same process, doing
those in a batch is more efficient while still being safe. Modify
process_madvise() entry level code path to do such batched tlb flushes,
while the internal unmap logic do only gathering of the tlb entries to
flush.
In more detail, modify the entry functions to initialize an mmu_gather
object and pass it to the internal logic. And make the internal logic do
only gathering of the tlb entries to flush into the received mmu_gather
object. After all internal function calls are done, the entry functions
flush the gathered tlb entries at once.
Because process_madvise() and madvise() share the internal unmap logic,
make same change to madvise() entry code together, to make code consistent
and cleaner. It is only for keeping the code clean, and shouldn't degrade
madvise(). It could rather provide a potential tlb flushes reduction
benefit for a case that there are multiple vmas for the given address
range. It is only a side effect from an effort to keep code clean, so we
don't measure it separately.
Similar optimizations might be applicable to other madvise behavior such
as MADV_COLD and MADV_PAGEOUT. Those are simply out of the scope of this
patch series, though.
Patches Sequence
================
The first patch defines a new data structure for managing information that
is required for batched tlb flushes (mmu_gather and behavior), and update
code paths for MADV_DONTNEED[_LOCKED] and MADV_FREE handling internal
logic to receive it.
The second patch batches tlb flushes for MADV_FREE handling for both
madvise() and process_madvise().
Remaining two patches are for MADV_DONTNEED[_LOCKED] tlb flushes batching.
The third patch splits zap_page_range_single() for batching of
MADV_DONTNEED[_LOCKED] handling. The fourth patch batches tlb flushes for
the hint using the sub-logic that the third patch split out, and the
helpers for batched tlb flushes that introduced for the MADV_FREE case, by
the second patch.
Test Results
============
I measured the latency to apply MADV_DONTNEED advice to 256 MiB memory
using multiple process_madvise() calls. I apply the advice in 4 KiB sized
regions granularity, but with varying batch size per process_madvise()
call (vlen) from 1 to 1024. The source code for the measurement is
available at GitHub[1]. To reduce measurement errors, I did the
measurement five times.
The measurement results are as below. 'sz_batch' column shows the batch
size of process_madvise() calls. 'Before' and 'After' columns show the
average of latencies in nanoseconds that measured five times on kernels
that built without and with the tlb flushes batching of this series
(patches 3 and 4), respectively. For the baseline, mm-new tree of
2025-04-09[2] has been used, after reverting the second version of this
patch series and adding a temporal fix for !CONFIG_DEBUG_VM build
failure[3]. 'B-stdev' and 'A-stdev' columns show ratios of latency
measurements standard deviation to average in percent for 'Before' and
'After', respectively. 'Latency_reduction' shows the reduction of the
latency that the 'After' has achieved compared to 'Before', in percent.
Higher 'Latency_reduction' values mean more efficiency improvements.
sz_batch Before B-stdev After A-stdev Latency_reduction
1
146386348 2.78
111327360.6 3.13 23.95
2
108222130 1.54
72131173.6 2.39 33.35
4
93617846.8 2.76
51859294.4 2.50 44.61
8
80555150.4 2.38
44328790 1.58 44.97
16
77272777 1.62
37489433.2 1.16 51.48
32
76478465.2 2.75
33570506 3.48 56.10
64
75810266.6 1.15
27037652.6 1.61 64.34
128
73222748 3.86
25517629.4 3.30 65.15
256
72534970.8 2.31
25002180.4 0.94 65.53
512
71809392 5.12
24152285.4 2.41 66.37
1024
73281170.2 4.53
24183615 2.09 67.00
Unexpectedly the latency has reduced (improved) even with batch size one.
I think some of compiler optimizations have affected that, like also
observed with the first version of this patch series.
So, please focus on the proportion between the improvement and the batch
size. As expected, tlb flushes batching provides latency reduction that
proportional to the batch size. The efficiency gain ranges from about 33
percent with batch size 2, and up to 67 percent with batch size 1,024.
Please note that this is a very simple microbenchmark, so real efficiency
gain on real workload could be very different.
This patch (of 4):
To implement batched tlb flushes for MADV_DONTNEED[_LOCKED] and MADV_FREE,
an mmu_gather object in addition to the behavior integer need to be passed
to the internal logics. Using a struct can make it easy without
increasing the number of parameters of all code paths towards the internal
logic. Define a struct for the purpose and use it on the code path that
starts from madvise_do_behavior() and ends on madvise_dontneed_free().
Note that this changes madvise_walk_vmas() visitor type signature, too.
Specifically, it changes its 'arg' type from 'unsigned long' to the new
struct pointer.
Link: https://lkml.kernel.org/r/20250410000022.1901-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250410000022.1901-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam R. Howlett <howlett@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Baolin Wang [Wed, 9 Apr 2025 09:38:58 +0000 (17:38 +0800)]
mm: huge_memory: add folio_mark_accessed() when zapping file THP
When investigating performance issues during file folio unmap, I noticed
some behavioral differences in handling non-PMD-sized folios and PMD-sized
folios. For non-PMD-sized file folios, it will call folio_mark_accessed()
to mark the folio as having seen activity, but this is not done for
PMD-sized folios.
This might not cause obvious issues, but a potential problem could be
that, it might lead to reclaim of hot file folios under memory pressure,
as quoted from Johannes:
: Sometimes file contents are only accessed through relatively short-lived
: mappings. But they can nevertheless be accessed a lot and be hot. It's
: important to not lose that information on unmap, and end up kicking out a
: frequently used cache page.
Therefore, we should also add folio_mark_accessed() for PMD-sized file
folios when unmapping.
[baolin.wang@linux.alibaba.com: add comment]
Link: https://lkml.kernel.org/r/23fdc11d-e983-4627-89a8-79e9ecf9a45a@linux.alibaba.com
Link: https://lkml.kernel.org/r/fc117f60d7b686f87067f36a0ef7cdbc3a78109c.1744190345.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lorenzo Stoakes [Tue, 8 Apr 2025 09:29:33 +0000 (10:29 +0100)]
tools/testing/selftests: assert that anon merge cases behave as expected
Prior to the recently applied commit that permits this merge,
mprotect()'ing a faulted VMA, adjacent to an unfaulted VMA, such that the
two share characteristics would fail to merge due to what appear to be
unintended consequences of commit
965f55dea0e3 ("mmap: avoid merging
cloned VMAs").
Now we have fixed this bug, assert that we can indeed merge anonymous VMAs
this way.
Also assert that forked source/target VMAs are equally rejected.
Previously, all empty target anon merges with one VMA faulted and the
other unfaulted would be rejected incorrectly, now we ensure that unforked
merge, but forked do not.
Additionally, add the new test file to the MEMORY MAPPING section in
MAINTAINERS, as these tests are explicitly memory mapping related.
Link: https://lkml.kernel.org/r/2b69330274a3b71721f7042c5eabe91143934415.1744104124.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lorenzo Stoakes [Tue, 8 Apr 2025 09:29:32 +0000 (10:29 +0100)]
tools/testing: add PROCMAP_QUERY helper functions in mm self tests
The PROCMAP_QUERY ioctl() is very useful - it allows for binary access to
/proc/$pid/[s]maps data and thus convenient lookup of data contained
there.
This patch exposes this for convenient use by mm self tests so the state
of VMAs can easily be queried.
Link: https://lkml.kernel.org/r/ce83d877093d1fc594762cf4b82f0c27963030ee.1744104124.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lorenzo Stoakes [Tue, 8 Apr 2025 09:29:31 +0000 (10:29 +0100)]
mm/vma: fix incorrectly disallowed anonymous VMA merges
Patch series "fix incorrectly disallowed anonymous VMA merges", v2.
It appears that we have been incorrectly rejecting merge cases for 15
years, apparently by mistake.
Imagine a range of anonymous mapped momemory divided into two VMAs like
this, with incompatible protection bits:
RW RWX
unfaulted faulted
|-----------|-----------|
| prev | vma |
|-----------|-----------|
mprotect(RW)
Now imagine mprotect()'ing vma so it is RW. This appears as if it should
merge, it does not.
Neither does this case, again mprotect()'ing vma RW:
RWX RW
faulted unfaulted
|-----------|-----------|
| vma | next |
|-----------|-----------|
mprotect(RW)
Nor:
RW RWX RW
unfaulted faulted unfaulted
|-----------|-----------|-----------|
| prev | vma | next |
|-----------|-----------|-----------|
mprotect(RW)
What's going on here?
In commit
5beb49305251 ("mm: change anon_vma linking to fix multi-process
server scalability issue"), from 2010, Rik von Riel took careful care to
account for these cases - commenting that '[this is] easily overlooked:
when mprotect shifts the boundary, make sure the expanding vma has
anon_vma set if the shrinking vma had, to cover any anon pages imported.'
However, commit
965f55dea0e3 ("mmap: avoid merging cloned VMAs")
introduced a little over a year later, appears to have accidentally
disallowed this.
By adjusting the is_mergeable_anon_vma() function to avoid lock contention
across large trees of forked anon_vma's, this commit wrongly assumed the
VMA being checked (the ostensible merge 'target') should be faulted, that
is, have an anon_vma, and thus an anon_vma_chain list established, but
only of length 1.
This appears to have been unintentional, as disallowing empty target VMAs
like this across the board makes no sense.
We already have logic that accounts for this case, the same logic Rik
introduced in 2010, now via dup_anon_vma() (and ultimately
anon_vma_clone()), so there is no problem permitting this.
This series fixes this mistake and also ensures that scalability concerns
remain addressed by explicitly checking that whatever VMA is being merged
has not been forked.
A full set of self tests which reproduce the issue are provided, as well
as updating userland VMA tests to assert this behaviour.
The self tests additionally assert scalability concerns are addressed.
This patch (of 3):
anon_vma_chain's were introduced by Rik von Riel in commit
5beb49305251
("mm: change anon_vma linking to fix multi-process server scalability
issue").
This patch was introduced in March 2010. As part of this change, careful
attention was made to the instance of mprotect() causing a VMA merge, with
one faulted (i.e. having anon_vma set) and another not:
/*
* Easily overlooked: when mprotect shifts the boundary,
* make sure the expanding vma has anon_vma set if the
* shrinking vma had, to cover any anon pages imported.
*/
In the modern VMA code, this is handled in dup_anon_vma() (and ultimately
anon_vma_clone()).
This case is one of the three configurations of adjacent VMA anon_vma
state that we might encounter on merge (where dst is the VMA which will be
merged into and src the one being merged into dst):
1. dst->anon_vma, src->anon_vma - These must be equal, no-op.
2. dst->anon_vma, !src->anon_vma - We simply use dst->anon_vma, no-op.
3. !dst->anon_vma, src->anon_vma - The case in question here.
In case 3, the instance addressed here - we duplicate the AVC connections
from src and place into dst.
However, in practice, we very often do NOT do this.
This appears to be due to an inadvertent consequence of the change
introduced by commit
965f55dea0e3 ("mmap: avoid merging cloned VMAs"),
introduced in May 2011.
This implies that this merge case was functional only for a little over a
year, and has since been broken for ~15 years.
Here, lock scalability concerns lead to us restricting anonymous merges
only to those VMAs with 1 entry in their vma->anon_vma_chain, that is, a
VMA that is not connected to any parent process's anon_vma.
The mergeability test looks like this:
static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1,
struct anon_vma *anon_vma2, struct vm_area_struct *vma)
{
if ((!anon_vma1 || !anon_vma2) && (!vma ||
!vma->anon_vma || list_is_singular(&vma->anon_vma_chain)))
return true;
return anon_vma1 == anon_vma2;
}
However, we have a problem here - typically the vma passed here is the
destination VMA.
For instance in vma_merge_existing_range() we invoke:
can_vma_merge_left()
-> [ check that there is an immediately adjacent prior VMA ]
-> can_vma_merge_after()
-> is_mergeable_vma() for general attribute check
-> is_mergeable_anon_vma([ proposed anon_vma ], prev->anon_vma, prev)
So if we were considering a target unfaulted 'prev':
unfaulted faulted
|-----------|-----------|
| prev | vma |
|-----------|-----------|
This would call is_mergeable_anon_vma(NULL, vma->anon_vma, prev).
The list_is_singular() check for vma->anon_vma_chain, an empty list on
fault, would cause this merge to _fail_ even though all else indicates a
merge.
Equally a simple merge into a next VMA would hit the same problem:
faulted unfaulted
|-----------|-----------|
| vma | next |
|-----------|-----------|
can_vma_merge_right()
-> [ check that there is an immediately adjacent succeeding VMA ]
-> can_vma_merge_before()
-> is_mergeable_vma() for general attribute check
-> is_mergeable_anon_vma([ proposed anon_vma ], next->anon_vma, next)
For a 3-way merge, we'd also hit the same problem if it was configured like
this for instance:
unfaulted faulted unfaulted
|-----------|-----------|-----------|
| prev | vma | next |
|-----------|-----------|-----------|
As we'd call can_vma_merge_left() for prev, and can_vma_merge_right() for
next, both of which would fail.
vma_merge_new_range() (and relatedly, vma_expand()) are not impacted, as
the new VMA would never already be faulted (it is a proposed new range).
Because we already handle each of the aforementioned merge cases, and can
absolutely therefore deal with an existing VMA merge with !dst->anon_vma,
src->anon_vma, there is absolutely no reason to disallow this kind of
merge.
It seems that the intention of this patch is to ensure that, in the
instance of merging unfaulted VMAs with faulted ones, we never wish to do
so with those with multiple AVCs due to the fact that anon_vma lock's are
held across both parent and child anon_vma's (actually, the 'root' parent
anon_vma's lock is used).
In fact, the original commit alludes to this - "find_mergeable_anon_vma()
already considers this case".
In find_mergeable_anon_vma() however, we check the anon_vma which will be
merged from, if it is set, then we check
list_is_singular(vma->anon_vma_chain).
So to match this logic, update is_mergeable_anon_vma() to perform this
scalability check on the VMA whose anon_vma we ultimately merge into.
This matches existing behaviour with forked VMAs, only we no longer
wrongly disallow ALL empty target merges.
So we both allow merge cases and ensure the scalability check is correctly
applied.
We may wish to revisit these lock scalability concerns at a later date and
ensure they are still valid.
Additionally, correct userland VMA tests which were mistakenly not
asserting these cases correctly previously to now correctly assert this,
and to ensure vmg->anon_vma state is always consistent to account for
newly introduced asserts.
Link: https://lkml.kernel.org/r/cover.1744104124.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/18c756fc9eaf7ad082a710c91133b8346f8cd9a8.1744104124.git.lorenzo.stoakes@oracle.com
Fixes:
965f55dea0e3 ("mmap: avoid merging cloned VMAs")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:46 +0000 (09:22 +0000)]
mm: rust: add MEMORY MANAGEMENT [RUST]
We have introduced Rust bindings for core mm abstractions as part of this
series, so add an entry in MAINTAINERS to be explicit about who maintains
this.
Patches are anticipated to be taken through the mm tree as usual with
other mm code.
Link: https://rust-for-linux.com/rust-kernel-policy#how-is-rust-introduced-in-a-subsystem
Link: https://lore.kernel.org/all/33e64b12-aa07-4e78-933a-b07c37ff1d84@lucifer.local/
Link: https://lkml.kernel.org/r/20250408-vma-v16-9-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:45 +0000 (09:22 +0000)]
task: rust: rework how current is accessed
Introduce a new type called `CurrentTask` that lets you perform various
operations that are only safe on the `current` task. Use the new type to
provide a way to access the current mm without incrementing its refcount.
With this change, you can write stuff such as
let vma = current!().mm().lock_vma_under_rcu(addr);
without incrementing any refcounts.
This replaces the existing abstractions for accessing the current pid
namespace. With the old approach, every field access to current involves
both a macro and a unsafe helper function. The new approach simplifies
that to a single safe function on the `CurrentTask` type. This makes it
less heavy-weight to add additional current accessors in the future.
That said, creating a `CurrentTask` type like the one in this patch
requires that we are careful to ensure that it cannot escape the current
task or otherwise access things after they are freed. To do this, I
declared that it cannot escape the current "task context" where I defined
a "task context" as essentially the region in which `current` remains
unchanged. So e.g., release_task() or begin_new_exec() would leave the
task context.
If a userspace thread returns to userspace and later makes another
syscall, then I consider the two syscalls to be different task contexts.
This allows values stored in that task to be modified between syscalls,
even if they're guaranteed to be immutable during a syscall.
Ensuring correctness of `CurrentTask` is slightly tricky if we also want
the ability to have a safe `kthread_use_mm()` implementation in Rust. To
support that safely, there are two patterns we need to ensure are safe:
// Case 1: current!() called inside the scope.
let mm;
kthread_use_mm(some_mm, || {
mm = current!().mm();
});
drop(some_mm);
mm.do_something(); // UAF
and:
// Case 2: current!() called before the scope.
let mm;
let task = current!();
kthread_use_mm(some_mm, || {
mm = task.mm();
});
drop(some_mm);
mm.do_something(); // UAF
The existing `current!()` abstraction already natively prevents the first
case: The `&CurrentTask` would be tied to the inner scope, so the
borrow-checker ensures that no reference derived from it can escape the
scope.
Fixing the second case is a bit more tricky. The solution is to
essentially pretend that the contents of the scope execute on an different
thread, which means that only thread-safe types can cross the boundary.
Since `CurrentTask` is marked `NotThreadSafe`, attempts to move it to
another thread will fail, and this includes our fake pretend thread
boundary.
This has the disadvantage that other types that aren't thread-safe for
reasons unrelated to `current` also cannot be moved across the
`kthread_use_mm()` boundary. I consider this an acceptable tradeoff.
Link: https://lkml.kernel.org/r/20250408-vma-v16-8-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:44 +0000 (09:22 +0000)]
rust: miscdevice: add mmap support
Add the ability to write a file_operations->mmap hook in Rust when using
the miscdevice abstraction. The `vma` argument to the `mmap` hook uses
the `VmaNew` type from the previous commit; this type provides the correct
set of operations for a file_operations->mmap hook.
Link: https://lkml.kernel.org/r/20250408-vma-v16-7-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:43 +0000 (09:22 +0000)]
mm: rust: add VmaNew for f_ops->mmap()
This type will be used when setting up a new vma in an f_ops->mmap() hook.
Using a separate type from VmaRef allows us to have a separate set of
operations that you are only able to use during the mmap() hook. For
example, the VM_MIXEDMAP flag must not be changed after the initial setup
that happens during the f_ops->mmap() hook.
To avoid setting invalid flag values, the methods for clearing VM_MAYWRITE
and similar involve a check of VM_WRITE, and return an error if VM_WRITE
is set. Trying to use `try_clear_maywrite` without checking the return
value results in a compilation error because the `Result` type is marked
#[must_use].
For now, there's only a method for VM_MIXEDMAP and not VM_PFNMAP. When we
add a VM_PFNMAP method, we will need some way to prevent you from setting
both VM_MIXEDMAP and VM_PFNMAP on the same vma.
Link: https://lkml.kernel.org/r/20250408-vma-v16-6-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:42 +0000 (09:22 +0000)]
mm: rust: add mmput_async support
Adds an MmWithUserAsync type that uses mmput_async when dropped but is
otherwise identical to MmWithUser. This has to be done using a separate
type because the thing we are changing is the destructor.
Rust Binder needs this to avoid a certain deadlock. See commit
9a9ab0d96362 ("binder: fix race between mmput() and do_exit()") for
details. It's also needed in the shrinker to avoid cleaning up the mm in
the shrinker's context.
Link: https://lkml.kernel.org/r/20250408-vma-v16-5-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:41 +0000 (09:22 +0000)]
mm: rust: add lock_vma_under_rcu
Currently, the binder driver always uses the mmap lock to make changes to
its vma. Because the mmap lock is global to the process, this can involve
significant contention. However, the kernel has a feature called per-vma
locks, which can significantly reduce contention. For example, you can
take a vma lock in parallel with an mmap write lock. This is important
because contention on the mmap lock has been a long-term recurring
challenge for the Binder driver.
This patch introduces support for using `lock_vma_under_rcu` from Rust.
The Rust Binder driver will be able to use this to reduce contention on
the mmap lock.
Link: https://lkml.kernel.org/r/20250408-vma-v16-4-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:40 +0000 (09:22 +0000)]
mm: rust: add vm_insert_page
The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP
flag, so we introduce a new type to keep track of such vmas.
The approach used in this patch assumes that we will not need to encode
many flag combinations in the type. I don't think we need to encode more
than VM_MIXEDMAP and VM_PFNMAP as things are now. However, if that
becomes necessary, using generic parameters in a single type would scale
better as the number of flags increases.
Link: https://lkml.kernel.org/r/20250408-vma-v16-3-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:39 +0000 (09:22 +0000)]
mm: rust: add vm_area_struct methods that require read access
This adds a type called VmaRef which is used when referencing a vma that
you have read access to. Here, read access means that you hold either the
mmap read lock or the vma read lock (or stronger).
Additionally, a vma_lookup method is added to the mmap read guard, which
enables you to obtain a &VmaRef in safe Rust code.
This patch only provides a way to lock the mmap read lock, but a follow-up
patch also provides a way to just lock the vma read lock.
Link: https://lkml.kernel.org/r/20250408-vma-v16-2-d8b446e885d9@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Alice Ryhl [Tue, 8 Apr 2025 09:22:38 +0000 (09:22 +0000)]
mm: rust: add abstraction for struct mm_struct
Patch series "Rust support for mm_struct, vm_area_struct, and mmap", v16.
This updates the vm_area_struct support to use the approach we discussed
at LPC where there are several different Rust wrappers for vm_area_struct
depending on the kind of access you have to the vma. Each case allows a
different set of operations on the vma.
This includes an MM MAINTAINERS entry as proposed by Lorenzo:
https://lore.kernel.org/all/
33e64b12-aa07-4e78-933a-
b07c37ff1d84@lucifer.local/
This patch (of 9):
These abstractions allow you to reference a `struct mm_struct` using both
mmgrab and mmget refcounts. This is done using two Rust types:
* Mm - represents an mm_struct where you don't know anything about the
value of mm_users.
* MmWithUser - represents an mm_struct where you know at compile time
that mm_users is non-zero.
This allows us to encode in the type system whether a method requires that
mm_users is non-zero or not. For instance, you can always call
`mmget_not_zero` but you can only call `mmap_read_lock` when mm_users is
non-zero.
The struct is called Mm to keep consistency with the C side.
The ability to obtain `current->mm` is added later in this series.
The mm module is defined to only exist when CONFIG_MMU is set. This
avoids various errors due to missing types and functions when CONFIG_MMU
is disabled. More fine-grained cfgs can be considered in the future. See
the thread at [1] for more info.
Link: https://lkml.kernel.org/r/20250408-vma-v16-9-d8b446e885d9@google.com
Link: https://lkml.kernel.org/r/20250408-vma-v16-1-d8b446e885d9@google.com
Link: https://lore.kernel.org/all/202503091916.QousmtcY-lkp@intel.com/
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Balbir Singh <balbirs@nvidia.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:22 +0000 (10:52 +0100)]
riscv: mm: call PUD/P4D ctor in special kernel pgtable alloc
Constructors for PUD/P4D-level pgtables were recently introduced. They
should be called for all pgtables; make sure they are called for special
kernel mappings created by create_pgd_mapping() too.
While at it also switch to using pagetable_alloc() like in
alloc_{pte,pmd}_late().
Link: https://lkml.kernel.org/r/20250408095222.860601-13-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:21 +0000 (10:52 +0100)]
arm64: mm: call PUD/P4D ctor in __create_pgd_mapping()
Constructors for PUD/P4D-level pgtables were recently introduced. They
should be called for all pgtables; make sure they are called for special
kernel mappings created by __create_pgd_mapping() too.
Link: https://lkml.kernel.org/r/20250408095222.860601-12-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:20 +0000 (10:52 +0100)]
riscv: mm: clarify ctor mm argument in alloc_{pte,pmd}_late
pagetable_{pte,pmd}_ctor(mm, ptdesc) skip the ptlock initialisation if mm
is &init_mm. To avoid unnecessary overhead, it is therefore preferable to
pass the actual mm associated to the PTE/PMD.
Unfortunately, this proves challenging for alloc_{pte,pmd}_late() as the
associated mm is not available at the point where they are called - in
fact not even top-level functions like create_pgd_mapping() are passed the
mm. As a result they both call the ctor with NULL as mm; this is safe but
potentially wasteful.
This is not a new situation, but let's add a couple of comments to clarify
it.
Link: https://lkml.kernel.org/r/20250408095222.860601-11-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:19 +0000 (10:52 +0100)]
arm64: mm: always call PTE/PMD ctor in __create_pgd_mapping()
TL;DR: always call the PTE/PMD ctor, passing the appropriate mm to skip
ptlock_init() if unneeded.
__create_pgd_mapping() is used for creating different kinds of mappings,
and may allocate page table pages if passed an allocator callback. There
are currently three such cases:
1. create_pgd_mapping(), which is used to create the EFI mapping
2. arch_add_memory()
3. map_entry_trampoline()
1. uses pgd_pgtable_alloc() as allocator callback, which calls the
PTE/PMD ctor, while 2. and 3. use __pgd_pgtable_alloc(), which does not.
The rationale is most likely that pgtables associated with init_mm do not
make use of split page table locks, and it is therefore unnecessary to
initialise them by calling the ctor. 2. operates on swapper_pg_dir so
the allocated pgtables are clearly associated with init_mm, this is
arguably the case for 3. too (the trampoline mapping is never modified so
ptlocks are anyway irrelevant). 1. corresponds to efi_mm so ptlocks need
to be initialised in that case.
We are now moving towards calling the ctor for all page tables, even those
associated with init_mm. pagetable_{pte,pmd}_ctor() have become aware of
the associated mm so that the ptlock initialisation can be skipped for
init_mm. This patch therefore amends the allocator callbacks so that the
PTE/PMD ctor are always called, with an appropriate mm pointer to avoid
unnecessary ptlock overhead.
Modifying the prototype of the allocator callbacks to take the mm and
propagating that pointer all the way down would be pretty invasive.
Instead:
* __pgd_pgtable_alloc() (cases 2. and 3. above) is replaced with
pgd_pgtable_alloc_init_mm(), resulting in the ctors being called with
&init_mm. This is the main functional change in this patch; the ptlock
still isn't initialised, but other ctor actions (e.g.
accounting-related) are now carried out for those allocated pgtables.
* pgd_pgtable_alloc() (case 1. above) is replaced with
pgd_pgtable_alloc_special_mm(), resulting in the ctors being called with
NULL as mm. No functional change here; NULL essentially means "not
init_mm", and the ptlock is still initialised.
__pgd_pgtable_alloc() is now the common implementation of those two
helpers. While at it we switch it to using pagetable_alloc() like
standard pgtable allocator functions and remove the comment regarding ctor
calls (ctors are now always expected to be called).
Link: https://lkml.kernel.org/r/20250408095222.860601-10-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:18 +0000 (10:52 +0100)]
arm64: mm: use enum to identify pgtable level instead of *_SHIFT
Commit
90292aca9854 ("arm64: mm: use appropriate ctors for page tables")
introduced pgtable ctor calls in pgd_pgtable_alloc(). To identify the
pgtable level and call the appropriate ctor, the *_SHIFT value associated
with the pgtable level is used. However, those values do not
unambiguously identify a level, because if a given level is folded, the
*_SHIFT value will be equal to that of the upper level (e.g. PMD_SHIFT ==
PUD_SHIFT if PMD is folded).
As things stand, there is probably not much damaged done by calling the
ctor for a different level, and ARCH_ENABLE_SPLIT_PMD_PTLOCK is only
selected if PMD isn't folded (so we don't needlessly initialise
pmd_ptlock). Still, this is pretty confusing, and it would get even more
confusing when adding ctor calls for the remaining levels.
Let's simplify all this by using an enum to identify the pgtable level
instead; this way folding becomes irrelevant. This is inspired by one of
the m68k pgtable allocators (arch/m68k/include/asm/motorola_pgalloc.h).
Link: https://lkml.kernel.org/r/20250408095222.860601-9-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:17 +0000 (10:52 +0100)]
mm: skip ptlock_init() for kernel PMDs
Split page table locks are not used for pgtables associated to init_mm, at
any level. pte_alloc_kernel() does not call ptlock_init() as a result.
There is however no separate alloc/free functions for kernel PMDs, and
pmd_ptlock_init() is called unconditionally. When ALLOC_SPLIT_PTLOCKS is
true (e.g. 32-bit architectures or if CONFIG_PREEMPT_RT is selected),
this results in unnecessary dynamic memory allocation every time a kernel
PMD is allocated.
Now that pagetable_pmd_ctor() is passed the associated mm, we can easily
remove this overhead by skipping pmd_ptlock_init() if the pgtable is
associated to init_mm. No special-casing is needed on the dtor path, as
ptlock_free() is already called unconditionally for all levels.
(ptlock_free() is a no-op unless a ptlock was allocated for the given
PTP.)
Link: https://lkml.kernel.org/r/20250408095222.860601-8-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:16 +0000 (10:52 +0100)]
sparc64: mm: call ctor/dtor for kernel PTEs
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor, without initialising the ptlock needlessly as
pagetable_pte_ctor() skips it for init_mm.
Align sparc64 with the generic implementation by ensuring
pagetable_pte_[cd]tor() are called for kernel PTEs. As a result the
kernel and user alloc/free functions have the same implementation, and
since pgtable_t is defined as pte_t *, we can have both call a common
helper.
Link: https://lkml.kernel.org/r/20250408095222.860601-7-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:15 +0000 (10:52 +0100)]
powerpc: mm: call ctor/dtor for kernel PTEs
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor, without initialising the ptlock needlessly as
pagetable_pte_ctor() skips it for init_mm.
On powerpc, all functions related to PTE allocation are implemented by
common helpers, which are passed a boolean to differentiate user from
kernel pgtables. This patch aligns the powerpc implementation with the
generic one by calling pagetable_pte_[cd]tor() unconditionally in those
helpers.
Link: https://lkml.kernel.org/r/20250408095222.860601-6-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:14 +0000 (10:52 +0100)]
m68k: mm: call ctor/dtor for kernel PTEs
The generic implementation of pte_{alloc_one,free}_kernel now calls the
[cd]tor. Align the m68k/ColdFire implementation of those functions by
calling the [cd]tor explicitly.
Link: https://lkml.kernel.org/r/20250408095222.860601-5-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:13 +0000 (10:52 +0100)]
mm: call ctor/dtor for kernel PTEs
Since [1], constructors/destructors are expected to be called for all page
table pages, at all levels and for both user and kernel pgtables. There
is however one glaring exception: kernel PTEs are managed via separate
helpers (pte_alloc_kernel/pte_free_kernel), which do not call the [cd]tor,
at least not in the generic implementation.
The most obvious reason for this anomaly is that init_mm is special-cased
not to use split page table locks. As a result calling ptlock_init() for
PTEs associated with init_mm would be wasteful, potentially resulting in
dynamic memory allocation. However, pgtable [cd]tors perform other
actions - currently related to accounting/statistics, and potentially more
functionally significant in the future.
Now that pagetable_pte_ctor() is passed the associated mm, we can make it
skip the call to ptlock_init() for init_mm; this allows us to call the
ctor from pte_alloc_one_kernel() too. This is matched by a call to the
pgtable destructor in pte_free_kernel(); no special-casing is needed on
that path, as ptlock_free() is already called unconditionally.
(ptlock_free() is a no-op unless a ptlock was allocated for the given
PTP.)
This patch ensures that all architectures that rely on
<asm-generic/pgalloc.h> call the [cd]tor for kernel PTEs.
pte_free_kernel() cannot be overridden so changing the generic
implementation is sufficient. pte_alloc_one_kernel() can be overridden
using __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL, and a few architectures implement
it by calling the page allocator directly. We amend those so that they
call the generic __pte_alloc_one_kernel() instead, if possible, ensuring
that the ctor is called.
A few architectures do not use <asm-generic/pgalloc.h>; those will be
taken care of separately.
[1] https://lore.kernel.org/linux-mm/
20250103184415.
2744423-1-kevin.brodsky@arm.com/
Link: https://lkml.kernel.org/r/20250408095222.860601-4-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:12 +0000 (10:52 +0100)]
x86: pgtable: always use pte_free_kernel()
Page table pages are normally freed using the appropriate helper for the
given page table level. On x86, pud_free_pmd_page() and
pmd_free_pte_page() are an exception to the rule: they call free_page()
directly.
Constructor/destructor calls are about to be introduced for kernel PTEs.
To avoid missing dtor calls in those helpers, free the PTE pages using
pte_free_kernel() instead of free_page().
While at it also use pmd_free() instead of calling pagetable_dtor()
explicitly at the PMD level.
Link: https://lkml.kernel.org/r/20250408095222.860601-3-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kevin Brodsky [Tue, 8 Apr 2025 09:52:11 +0000 (10:52 +0100)]
mm: pass mm down to pagetable_{pte,pmd}_ctor
Patch series "Always call constructor for kernel page tables", v2.
There has been much confusion around exactly when page table
constructors/destructors (pagetable_*_[cd]tor) are supposed to be called.
They were initially introduced for user PTEs only (to support split page
table locks), then at the PMD level for the same purpose. Accounting was
added later on, starting at the PTE level and then moving to higher levels
(PMD, PUD). Finally, with my earlier series "Account page tables at all
levels" [1], the ctor/dtor is run for all levels, all the way to PGD.
I thought this was the end of the story, and it hopefully is for user
pgtables, but I was wrong for what concerns kernel pgtables. The current
situation there makes very little sense:
* At the PTE level, the ctor/dtor is not called (at least in the generic
implementation). Specific helpers are used for kernel pgtables at this
level (pte_{alloc,free}_kernel()) and those have never called the
ctor/dtor, most likely because they were initially irrelevant in the
kernel case.
* At all other levels, the ctor/dtor is normally called. This is
potentially wasteful at the PMD level (more on that later).
This series aims to ensure that the ctor/dtor is always called for kernel
pgtables, as it already is for user pgtables. Besides consistency, the
main motivation is to guarantee that ctor/dtor hooks are systematically
called; this makes it possible to insert hooks to protect page tables [2],
for instance. There is however an extra challenge: split locks are not
used for kernel pgtables, and it would therefore be wasteful to initialise
them (ptlock_init()).
It is worth clarifying exactly when split locks are used. They clearly
are for user pgtables, but as illustrated in commit
61444cde9170 ("ARM:
8591/1: mm: use fully constructed struct pages for EFI pgd allocations"),
they also are for special page tables like efi_mm. The one case where
split locks are definitely unused is pgtables owned by init_mm; this is
consistent with the behaviour of apply_to_pte_range().
The approach chosen in this series is therefore to pass the mm associated
to the pgtables being constructed to pagetable_{pte,pmd}_ctor() (patch 1),
and skip ptlock_init() if mm == &init_mm (patch 3 and 7). This makes it
possible to call the PTE ctor/dtor from pte_{alloc,free}_kernel() without
unintended consequences (patch 3). As a result the accounting functions
are now called at all levels for kernel pgtables, and split locks are
never initialised.
In configurations where ptlocks are dynamically allocated (32-bit,
PREEMPT_RT, etc.) and ARCH_ENABLE_SPLIT_PMD_PTLOCK is selected, this
series results in the removal of a kmem_cache allocation for every kernel
PMD. Additionally, for certain architectures that do not use
<asm-generic/pgalloc.h> such as s390, the same optimisation occurs at the
PTE level.
===
Things get more complicated when it comes to special pgtable allocators
(patch 8-12). All architectures need such allocators to create initial
kernel pgtables; we are not concerned with those as the ctor cannot be
called so early in the boot sequence. However, those allocators may also
be used later in the boot sequence or during normal operations. There are
two main use-cases:
1. Mapping EFI memory: efi_mm (arm, arm64, riscv)
2. arch_add_memory(): init_mm
The ctor is already explicitly run (at the PTE/PMD level) in the first
case, as required for pgtables that are not associated with init_mm.
However the same allocators may also be used for the second use-case (or
others), and this is where it gets messy. Patch 1 calls the ctor with
NULL as mm in those situations, as the actual mm isn't available.
Practically this means that ptlocks will be unconditionally initialised.
This is fine on arm - create_mapping_late() is only used for the EFI
mapping. On arm64, __create_pgd_mapping() is also used by
arch_add_memory(); patch 8/9/11 ensure that ctors are called at all levels
with the appropriate mm. The situation is similar on riscv, but
propagating the mm down to the ctor would require significant refactoring.
Since they are already called unconditionally, this series leaves riscv
no worse off - patch 10 adds comments to clarify the situation.
From a cursory look at other architectures implementing arch_add_memory(),
s390 and x86 may also need a similar treatment to add constructor calls.
This is to be taken care of in a future version or as a follow-up.
===
The complications in those special pgtable allocators beg the question:
does it really make sense to treat efi_mm and init_mm differently in e.g.
apply_to_pte_range()? Maybe what we really need is a way to tell if an mm
corresponds to user memory or not, and never use split locks for non-user
mm's. Feedback and suggestions welcome!
This patch (of 12):
In preparation for calling constructors for all kernel page tables while
eliding unnecessary ptlock initialisation, let's pass down the associated
mm to the PTE/PMD level ctors. (These are the two levels where ptlocks
are used.)
In most cases the mm is already around at the point of calling the ctor so
we simply pass it down. This is however not the case for special page
table allocators:
* arch/arm/mm/mmu.c
* arch/arm64/mm/mmu.c
* arch/riscv/mm/init.c
In those cases, the page tables being allocated are either for standard
kernel memory (init_mm) or special page directories, which may not be
associated to any mm. For now let's pass NULL as mm; this will be refined
where possible in future patches.
No functional change in this patch.
Link: https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/
Link: https://lore.kernel.org/linux-hardening/20250203101839.1223008-1-kevin.brodsky@arm.com/
Link: https://lkml.kernel.org/r/20250408095222.860601-1-kevin.brodsky@arm.com
Link: https://lkml.kernel.org/r/20250408095222.860601-2-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> [s390]
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: <x86@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Tue, 8 Apr 2025 15:15:49 +0000 (17:15 +0200)]
vmalloc: use for_each_vmap_node() in purge-vmap-area
Update a __purge_vmap_area_lazy() to use introduced helper. This is last
place in vmalloc code. Also this patch introduces an extra function which
is node_to_id() that converts a vmap_node pointer to an index in array.
__purge_vmap_area_lazy() requires that extra function.
Link: https://lkml.kernel.org/r/20250408151549.77937-3-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Tue, 8 Apr 2025 15:15:48 +0000 (17:15 +0200)]
vmalloc: switch to for_each_vmap_node() helper
There are places which can be updated easily to use the helper to iterate
over all vmap-nodes. This is what this patch does.
The aim is to improve readability and simplify the code.
[akpm@linux-foundation.org: fix build warning]
Link: https://lkml.kernel.org/r/20250408151549.77937-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Uladzislau Rezki (Sony) [Tue, 8 Apr 2025 15:15:47 +0000 (17:15 +0200)]
vmalloc: add for_each_vmap_node() helper
To simplify iteration over vmap-nodes, add the for_each_vmap_node() macro
that iterates over all nodes in a system. It tends to simplify the code.
Link: https://lkml.kernel.org/r/20250408151549.77937-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christop Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Liu Ye [Tue, 18 Mar 2025 06:32:26 +0000 (14:32 +0800)]
fs/proc/page: refactor to reduce code duplication
kpageflags_read() and kpagecgroup_read() are quite similar to
kpagecount_read(). Refactor common code into a helper function to reduce
code duplication.
Link: https://lkml.kernel.org/r/20250318063226.223284-1-liuyerd@163.com
Signed-off-by: Liu Ye <liuye@kylinos.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Svetly Todorov <svetly.todorov@memverge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Przemek Kitszel [Thu, 20 Mar 2025 10:22:19 +0000 (11:22 +0100)]
xarray: make xa_alloc_cyclic() return 0 on all success cases
Change xa_alloc_cyclic() to return 0 even on wrap-around. Do the same for
xa_alloc_cyclic_irq() and xa_alloc_cyclic_bh().
This will prevent any future bug of treating return of 1 as an error:
int ret = xa_alloc_cyclic(...)
if (ret) // currently mishandles ret==1
goto failure;
If there will be someone interested in when wrap-around occurs, there is
still __xa_alloc_cyclic() that behaves as before. For now there is no
such user.
Link: https://lkml.kernel.org/r/20250320102219.8101-1-przemyslaw.kitszel@intel.com
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/netdev/Z9gUd-5t8b5NX2wE@casper.infradead.org
Cc: Andriy Shevchenko <andriy.shevchenko@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Cc: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Anshuman Khandual [Mon, 7 Apr 2025 05:31:13 +0000 (11:01 +0530)]
arm64/mm: define ptdesc_t
Define ptdesc_t type which describes the basic page table descriptor
layout on arm64 platform. Subsequently all level specific pxxval_t
descriptors are derived from ptdesc_t thus establishing a common original
format, which can also be appropriate for page table entries, masks and
protection values etc which are used at all page table levels.
Link: https://lkml.kernel.org/r/20250407053113.746295-4-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Suggested-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Anshuman Khandual [Mon, 7 Apr 2025 05:31:12 +0000 (11:01 +0530)]
mm/ptdump: split effective_prot() into level specific callbacks
Last argument in effective_prot() is u64 assuming pxd_val() returned value
(all page table levels) is 64 bit. pxd_val() is very platform specific
and its type should not be assumed in generic MM.
Split effective_prot() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then the
subscribing platform (only x86) just derive pxd_val() from the entries as
required and proceed as earlier.
Link: https://lkml.kernel.org/r/20250407053113.746295-3-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Anshuman Khandual [Mon, 7 Apr 2025 05:31:11 +0000 (11:01 +0530)]
mm/ptdump: split note_page() into level specific callbacks
Patch series "mm/ptdump: Drop assumption that pxd_val() is u64", v2.
Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform.
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM. A similar problem exists for effective_prot(),
although it is restricted to x86 platform.
This series splits note_page() and effective_prot() into individual page
table level specific callbacks which accepts corresponding pxd_t page
table entry as an argument instead and later on all subscribing platforms
could derive pxd_val() from the table entries as required and proceed as
before.
Define ptdesc_t type which describes the basic page table descriptor
layout on arm64 platform. Subsequently all level specific pxxval_t
descriptors are derived from ptdesc_t thus establishing a common original
format, which can also be appropriate for page table entries, masks and
protection values etc which are used at all page table levels.
This patch (of 3):
Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform.
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM.
Split note_page() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then subscribing
platforms just derive pxd_val() from the entries as required and proceed
as earlier.
Also add a note_page_flush() callback for flushing the last page table
page that was being handled earlier via level = -1.
Link: https://lkml.kernel.org/r/20250407053113.746295-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20250407053113.746295-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Li Wang [Mon, 7 Apr 2025 08:42:01 +0000 (16:42 +0800)]
selftest/mm: make hugetlb_reparenting_test tolerant to async reparenting
In cgroup v2, memory and hugetlb usage reparenting is asynchronous. This
can cause test flakiness when immediately asserting usage after deleting a
child cgroup. To address this, add a helper function
`assert_with_retry()` that checks usage values with a timeout-based retry.
This improves test stability without relying on fixed sleep delays.
Also bump up the tolerance size to 7MB.
To avoid False Positives:
...
# Assert memory charged correctly for child only use.
# actual a = 11 MB
# expected a = 0 MB
# fail
# cleanup
# [FAIL]
not ok 11 hugetlb_reparenting_test.sh -cgroup-v2 # exit=1
# 0
# SUMMARY: PASS=10 SKIP=0 FAIL=1
Link: https://lkml.kernel.org/r/20250407084201.74492-1-liwang@redhat.com
Signed-off-by: Li Wang <liwang@redhat.com>
Tested-by: Donet Tom <donettom@linux.ibm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Johannes Weiner [Mon, 7 Apr 2025 18:01:54 +0000 (14:01 -0400)]
mm: page_alloc: tighten up find_suitable_fallback()
find_suitable_fallback() is not as efficient as it could be, and somewhat
difficult to follow.
1. should_try_claim_block() is a loop invariant. There is no point in
checking fallback areas if the caller is interested in claimable
blocks but the order and the migratetype don't allow for that.
2. __rmqueue_steal() doesn't care about claimability, so it shouldn't
have to run those tests.
Different callers want different things from this helper:
1. __compact_finished() scans orders up until it finds a claimable block
2. __rmqueue_claim() scans orders down as long as blocks are claimable
3. __rmqueue_steal() doesn't care about claimability at all
Move should_try_claim_block() out of the loop. Only test it for the
two callers who care in the first place. Distinguish "no blocks" from
"order + mt are not claimable" in the return value; __rmqueue_claim()
can stop once order becomes unclaimable, __compact_finished() can keep
advancing until order becomes claimable.
Before:
Performance counter stats for './run case-lru-file-mmap-read' (5 runs):
85,294.85 msec task-clock # 5.644 CPUs utilized ( +- 0.32% )
15,968 context-switches # 187.209 /sec ( +- 3.81% )
153 cpu-migrations # 1.794 /sec ( +- 3.29% )
801,808 page-faults # 9.400 K/sec ( +- 0.10% )
733,358,331,786 instructions # 1.87 insn per cycle ( +- 0.20% ) (64.94%)
392,622,904,199 cycles # 4.603 GHz ( +- 0.31% ) (64.84%)
148,563,488,531 branches # 1.742 G/sec ( +- 0.18% ) (63.86%)
152,143,228 branch-misses # 0.10% of all branches ( +- 1.19% ) (62.82%)
15.1128 +- 0.0637 seconds time elapsed ( +- 0.42% )
After:
Performance counter stats for './run case-lru-file-mmap-read' (5 runs):
84,380.21 msec task-clock # 5.664 CPUs utilized ( +- 0.21% )
16,656 context-switches # 197.392 /sec ( +- 3.27% )
151 cpu-migrations # 1.790 /sec ( +- 3.28% )
801,703 page-faults # 9.501 K/sec ( +- 0.09% )
731,914,183,060 instructions # 1.88 insn per cycle ( +- 0.38% ) (64.90%)
388,673,535,116 cycles # 4.606 GHz ( +- 0.24% ) (65.06%)
148,251,482,143 branches # 1.757 G/sec ( +- 0.37% ) (63.92%)
149,766,550 branch-misses # 0.10% of all branches ( +- 1.22% ) (62.88%)
14.8968 +- 0.0486 seconds time elapsed ( +- 0.33% )
Link: https://lkml.kernel.org/r/20250407180154.63348-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Carlos Song <carlos.song@nxp.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Hildenbrand [Fri, 21 Mar 2025 11:37:13 +0000 (12:37 +0100)]
kernel/events/uprobes: uprobe_write_opcode() rewrite
uprobe_write_opcode() does some pretty low-level things that really, it
shouldn't be doing: for example, manually breaking COW by allocating
anonymous folios and replacing mapped pages.
Further, it does seem to do some shaky things: for example, writing to
possible COW-shared anonymous pages or zapping anonymous pages that might
be pinned. We're also not taking care of uffd, uffd-wp, softdirty ...
although rather corner cases here. Let's just get it right like ordinary
ptrace writes would.
Let's rewrite the code, leaving COW-breaking to core-MM, triggered by
FOLL_FORCE|FOLL_WRITE (note that the code was already using FOLL_FORCE).
We'll use GUP to lookup/faultin the page and break COW if required. Then,
we'll walk the page tables using a folio_walk to perform our page
modification atomically by temporarily unmap the PTE + flushing the TLB.
Likely, we could avoid the temporary unmap in case we can just atomically
write the instruction, but that will be a separate project.
Unfortunately, we still have to implement the zapping logic manually,
because we only want to zap in specific circumstances (e.g., page content
identical).
Note that we can now handle large folios (compound pages) and the shared
zeropage just fine, so drop these checks.
Link: https://lkml.kernel.org/r/20250321113713.204682-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Hildenbrand [Fri, 21 Mar 2025 11:37:12 +0000 (12:37 +0100)]
kernel/events/uprobes: pass VMA to set_swbp(), set_orig_insn() and uprobe_write_opcode()
We already have the VMA, no need to look it up using
get_user_page_vma_remote(). We can now switch to get_user_pages_remote().
Link: https://lkml.kernel.org/r/20250321113713.204682-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Hildenbrand [Fri, 21 Mar 2025 11:37:11 +0000 (12:37 +0100)]
kernel/events/uprobes: pass VMA instead of MM to remove_breakpoint()
Patch series "kernel/events/uprobes: uprobe_write_opcode() rewrite", v3.
Currently, uprobe_write_opcode() implements COW-breaking manually, which
is really far from ideal. Further, there is interest in supporting
uprobes on hugetlb pages [1], and leaving at least the COW-breaking to the
core will make this much easier.
Also, I think the current code doesn't really handle some things properly
(see patch #3) when replacing/zapping pages.
Let's rewrite it, to leave COW-breaking to the fault handler, and handle
registration/unregistration by temporarily unmapping the anonymous page,
modifying it, and mapping it again. We still have to implement zapping of
anonymous pages ourselves, unfortunately.
We could look into not performing the temporary unmapping if we can
perform the write atomically, which would likely also make adding hugetlb
support a lot easier. But, limited (e.g., only PMD/PUD) hugetlb support
could be added on top of this with some tweaking.
Note that we now won't have to allocate another anonymous folio when
unregistering (which will be beneficial for hugetlb as well), we can
simply modify the already-mapped one from the registration (if any). When
registering a uprobe, we'll first trigger a ptrace-like write fault to
break COW, to then modify the already-mapped page.
Briefly sanity tested with perf probes and with the bpf uprobes selftest.
This patch (of 3):
Pass VMA instead of MM to remove_breakpoint() and remove the "MM" argument
from install_breakpoint(), because it can easily be derived from the VMA.
Link: https://lkml.kernel.org/r/20250321113713.204682-1-david@redhat.com
Link: https://lkml.kernel.org/r/20250321113713.204682-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: tongtiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Gavin Shan [Fri, 21 Mar 2025 12:02:22 +0000 (22:02 +1000)]
mm/debug: fix parameter passed to page_mapcount_is_type()
As the comments of page_mapcount_is_type() indicate, the parameter passed
to the function should be one more than page->_mapcount. However,
page->_mapcount is passed to the function by commit
4ffca5a96678 ("mm:
support only one page_type per page") where page_type_has_type() is
replaced by page_mapcount_is_type(), but the parameter isn't adjusted.
Fix the parameter for page_mapcount_is_type() to be (page->__mapcount +
1). Note that the issue doesn't cause any visible impacts due to the
safety gap introduced by PGTY_mapcount_underflow limit.
[akpm@linux-foundation.org: simplify __dump_folio(), per David]
Link: https://lkml.kernel.org/r/20250321120222.1456770-3-gshan@redhat.com
Fixes:
4ffca5a96678 ("mm: support only one page_type per page")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: gehao <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Gavin Shan [Fri, 21 Mar 2025 12:02:21 +0000 (22:02 +1000)]
mm: fix parameter passed to page_mapcount_is_type()
Patch series "Fix parameter passed to page_mapcount_is_type()", v2.
Found by code inspection. There are two places where the parameter passed
to page_mapcount_is_type() is (page->_mapcount), which is incorrect since
it should be one more than the value, as explained in the comments to
page_mapcount_is_type(): (a) page_has_type() in page-flags.h (b)
__dump_folio() in mm/debug.c
PATCH[1] fixes the parameter for (a)
PATCH[2] fixes the parameter for (b)
Note that the issue doesn't cause any visible impacts due to the safety
gap introduced by PGTY_mapcount_underflow limit. So the tag 'Cc:
stable@vger.kernel.org' isn't needed.
This patch (of 2):
As the comments of page_mapcount_is_type() indicate, the parameter passed
to the function should be one more than page->_mapcount. However,
page->_mapcount (equivalent to page->page_type) is passed to the function
by commit
4ffca5a96678 ("mm: support only one page_type per page")
page_type_has_type() is replaced by page_mapcount_is_type(), but the
parameter isn't adjusted.
Fix it by replacing page_mapcount_is_type() with page_type_has_type() in
page_has_type(). Note that the issue doesn't cause any visible impacts
due to the safety gap introduced by PGTY_mapcount_underflow limit.
Link: https://lkml.kernel.org/r/20250321120222.1456770-1-gshan@redhat.com
Link: https://lkml.kernel.org/r/20250321120222.1456770-2-gshan@redhat.com
Fixes:
4ffca5a96678 ("mm: support only one page_type per page")
Signed-off-by: Gavin Shan <gshan@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: gehao <gehao@kylinos.cn>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrei Vagin [Mon, 24 Mar 2025 06:53:28 +0000 (06:53 +0000)]
selftests/mm: add PAGEMAP_SCAN guard region test
Add a selftest to verify the PAGEMAP_SCAN ioctl correctly reports guard
regions using the newly introduced PAGE_IS_GUARD flag.
Link: https://lkml.kernel.org/r/20250324065328.107678-4-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrei Vagin [Mon, 24 Mar 2025 06:53:27 +0000 (06:53 +0000)]
tools headers UAPI: sync linux/fs.h with the kernel sources
Required for a new PAGEMAP_SCAN test to verify guard region reporting.
Link: https://lkml.kernel.org/r/20250324065328.107678-3-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrei Vagin [Mon, 24 Mar 2025 06:53:26 +0000 (06:53 +0000)]
fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions
Patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard
regions", v2.
Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions. This allows userspace tools, such as
CRIU, to detect and handle guard regions.
Currently, CRIU utilizes PAGEMAP_SCAN as a more efficient alternative to
parsing /proc/pid/pagemap. Without this change, guard regions are
incorrectly reported as swap-anon regions, leading CRIU to attempt dumping
them and subsequently failing.
The series includes updates to the documentation and selftests to reflect
the new functionality.
This patch (of 3):
Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions. This allows userspace tools, such as
CRIU, to detect and handle guard regions.
Link: https://lkml.kernel.org/r/20250324065328.107678-1-avagin@google.com
Link: https://lkml.kernel.org/r/20250324065328.107678-2-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sergey Senozhatsky [Tue, 25 Mar 2025 08:04:16 +0000 (17:04 +0900)]
zsmalloc: cleanup headers includes
Remove unused headers includes from zsmalloc and move pagemap.h and
migrate.h includes into zpdesc header.
Link: https://lkml.kernel.org/r/20250325080427.3449359-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:20:52 +0000 (13:20 +0200)]
selftests/ptrace: add a test case for PTRACE_SET_SYSCALL_INFO
Check whether PTRACE_SET_SYSCALL_INFO semantics implemented in the kernel
matches userspace expectations.
Link: https://lkml.kernel.org/r/20250303112052.GG24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:20:44 +0000 (13:20 +0200)]
ptrace: introduce PTRACE_SET_SYSCALL_INFO request
PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of system
calls the tracee is blocked in.
This API allows ptracers to obtain and modify system call details in a
straightforward and architecture-agnostic way, providing a consistent way
of manipulating the system call number and arguments across architectures.
As in case of PTRACE_GET_SYSCALL_INFO, PTRACE_SET_SYSCALL_INFO also does
not aim to address numerous architecture-specific system call ABI
peculiarities, like differences in the number of system call arguments for
such system calls as pread64 and preadv.
The current implementation supports changing only those bits of system
call information that are used by strace system call tampering, namely,
syscall number, syscall arguments, and syscall return value.
Support of changing additional details returned by
PTRACE_GET_SYSCALL_INFO, such as instruction pointer and stack pointer,
could be added later if needed, by using struct ptrace_syscall_info.flags
to specify the additional details that should be set. Currently, "flags"
and "reserved" fields of struct ptrace_syscall_info must be initialized
with zeroes; "arch", "instruction_pointer", and "stack_pointer" fields are
currently ignored.
PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations.
Other operations could be added later if needed.
Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen. The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure to
provide an API of changing the first system call argument on riscv
architecture.
ptrace(2) man page:
long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
Modify information about the system call that caused the stop.
The "data" argument is a pointer to struct ptrace_syscall_info
that specifies the system call information to be set.
The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).
Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
Link: https://lkml.kernel.org/r/20250303112044.GF24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Eugene Syromiatnikov <esyr@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:20:38 +0000 (13:20 +0200)]
ptrace_get_syscall_info: factor out ptrace_get_syscall_info_op
Move the code that calculates the type of the system call stop out of
ptrace_get_syscall_info() into a separate function
ptrace_get_syscall_info_op() which is going to be used later to implement
PTRACE_SET_SYSCALL_INFO API.
Link: https://lkml.kernel.org/r/20250303112038.GE24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:20:20 +0000 (13:20 +0200)]
syscall.h: introduce syscall_set_nr()
Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr() that complements
syscall_get_nr().
syscall_set_nr() is going to be needed along with syscall_set_arguments()
on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API.
Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> # mips
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:20:09 +0000 (13:20 +0200)]
syscall.h: add syscall_set_arguments()
This function is going to be needed on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.
This partially reverts commit
7962c2eddbfe ("arch: remove unused function
syscall_set_arguments()") by reusing some of old syscall_set_arguments()
implementations.
[nathan@kernel.org: fix compile time fortify checks]
Link: https://lkml.kernel.org/r/20250408213131.GA2872426@ax162
Link: https://lkml.kernel.org/r/20250303112009.GC24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> [mips]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dmitry V. Levin [Mon, 3 Mar 2025 11:19:53 +0000 (13:19 +0200)]
hexagon: add syscall_set_return_value()
Patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API", v7.
PTRACE_SET_SYSCALL_INFO is a generic ptrace API that complements
PTRACE_GET_SYSCALL_INFO by letting the ptracer modify details of system
calls the tracee is blocked in.
This API allows ptracers to obtain and modify system call details in a
straightforward and architecture-agnostic way, providing a consistent way
of manipulating the system call number and arguments across architectures.
As in case of PTRACE_GET_SYSCALL_INFO, PTRACE_SET_SYSCALL_INFO also does
not aim to address numerous architecture-specific system call ABI
peculiarities, like differences in the number of system call arguments for
such system calls as pread64 and preadv.
The current implementation supports changing only those bits of system
call information that are used by strace system call tampering, namely,
syscall number, syscall arguments, and syscall return value.
Support of changing additional details returned by
PTRACE_GET_SYSCALL_INFO, such as instruction pointer and stack pointer,
could be added later if needed, by using struct ptrace_syscall_info.flags
to specify the additional details that should be set. Currently, "flags"
and "reserved" fields of struct ptrace_syscall_info must be initialized
with zeroes; "arch", "instruction_pointer", and "stack_pointer" fields are
currently ignored.
PTRACE_SET_SYSCALL_INFO currently supports only PTRACE_SYSCALL_INFO_ENTRY,
PTRACE_SYSCALL_INFO_EXIT, and PTRACE_SYSCALL_INFO_SECCOMP operations.
Other operations could be added later if needed.
Ideally, PTRACE_SET_SYSCALL_INFO should have been introduced along with
PTRACE_GET_SYSCALL_INFO, but it didn't happen. The last straw that
convinced me to implement PTRACE_SET_SYSCALL_INFO was apparent failure to
provide an API of changing the first system call argument on riscv
architecture [1].
ptrace(2) man page:
long ptrace(enum __ptrace_request request, pid_t pid, void *addr, void *data);
...
PTRACE_SET_SYSCALL_INFO
Modify information about the system call that caused the stop.
The "data" argument is a pointer to struct ptrace_syscall_info
that specifies the system call information to be set.
The "addr" argument should be set to sizeof(struct ptrace_syscall_info)).
This patch (of 6):
hexagon is the only architecture that provides HAVE_ARCH_TRACEHOOK but
doesn't define syscall_set_return_value(). Since this function is going
to be needed on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API, add it on hexagon, too.
Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
Link: https://lkml.kernel.org/r/20250303111953.GB24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Maciej W. Rozycki <macro@orcam.me.uk>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SoumishDas [Tue, 25 Mar 2025 18:13:25 +0000 (23:43 +0530)]
mm: add kernel-doc comment for free_pgd_range()
Provide kernel-doc for free_pgd_range() so it's easier to understand what
the function does and how it is used.
Link: https://lkml.kernel.org/r/20250325181325.5774-1-soumish.das@gmail.com
Signed-off-by: SoumishDas <soumish.das@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Kemeng Shi [Tue, 25 Mar 2025 16:25:28 +0000 (00:25 +0800)]
mm: swap: replace cluster_swap_free_nr() with swap_entries_put_[map/cache]()
Replace cluster_swap_free_nr() with swap_entries_put_[map/cache]() to
remove repeat code and leverage batch-remove for entries with last flag.
After removing cluster_swap_free_nr, only functions with "_nr" suffix
could free entries spanning cross clusters. Add corresponding description
in comment of swap_entries_put_map_nr() as is first function with "_nr"
suffix and have a non-suffix variant function swap_entries_put_map().
Link: https://lkml.kernel.org/r/20250325162528.68385-9-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
projects / linux-block.git / log