mm: memcontrol: fix GFP_NOFS recursion in memory.high enforcement

Breno and Josef report a deadlock scenario from cgroup reclaim
re-entering the filesystem:

[  361.546690] ======================================================
[  361.559210] WARNING: possible circular locking dependency detected
[  361.571703] 6.5.0-0_fbk700_debug_rc0_kbuilder_13159_gbf787a128001 #1 Tainted: G S          E
[  361.589704] ------------------------------------------------------
[  361.602277] find/9315 is trying to acquire lock:
[  361.611625] ffff88837ba140c0 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0x68/0x4f0
[  361.631437]
[  361.631437] but task is already holding lock:
[  361.643243] ffff8881765b8678 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock+0x1e/0x40

[  362.904457]  mutex_lock_nested+0x1c/0x30
[  362.912414]  __btrfs_release_delayed_node+0x68/0x4f0
[  362.922460]  btrfs_evict_inode+0x301/0x770
[  362.982726]  evict+0x17c/0x380
[  362.988944]  prune_icache_sb+0x100/0x1d0
[  363.005559]  super_cache_scan+0x1f8/0x260
[  363.013695]  do_shrink_slab+0x2a2/0x540
[  363.021489]  shrink_slab_memcg+0x237/0x3d0
[  363.050606]  shrink_slab+0xa7/0x240
[  363.083382]  shrink_node_memcgs+0x262/0x3b0
[  363.091870]  shrink_node+0x1a4/0x720
[  363.099150]  shrink_zones+0x1f6/0x5d0
[  363.148798]  do_try_to_free_pages+0x19b/0x5e0
[  363.157633]  try_to_free_mem_cgroup_pages+0x266/0x370
[  363.190575]  reclaim_high+0x16f/0x1f0
[  363.208409]  mem_cgroup_handle_over_high+0x10b/0x270
[  363.246678]  try_charge_memcg+0xaf2/0xc70
[  363.304151]  charge_memcg+0xf0/0x350
[  363.320070]  __mem_cgroup_charge+0x28/0x40
[  363.328371]  __filemap_add_folio+0x870/0xd50
[  363.371303]  filemap_add_folio+0xdd/0x310
[  363.399696]  __filemap_get_folio+0x2fc/0x7d0
[  363.419086]  pagecache_get_page+0xe/0x30
[  363.427048]  alloc_extent_buffer+0x1cd/0x6a0
[  363.435704]  read_tree_block+0x43/0xc0
[  363.443316]  read_block_for_search+0x361/0x510
[  363.466690]  btrfs_search_slot+0xc8c/0x1520

This is caused by the mem_cgroup_handle_over_high() not respecting the
gfp_mask of the allocation context.  We used to only call this function on
resume to userspace, where no locks were held.  But c9afe31ec443 ("memcg:
synchronously enforce memory.high for large overcharges") added a call
from the allocation context without considering the gfp.

Link: https://lkml.kernel.org/r/20230914152139.100822-1-hannes@cmpxchg.org
Fixes: c9afe31ec443 ("memcg: synchronously enforce memory.high for large overcharges")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Breno Leitao <leitao@debian.org>
Reported-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>	[5.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ab94ad4597d07373b813f110092ebaa3cf5527c5..e4e24da16d2c398493e197cfb97f25be9940e3d0 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -920,7 +920,7 @@ unsigned long mem_cgroup_get_zone_lru_size(struct lruvec *lruvec,
        return READ_ONCE(mz->lru_zone_size[zone_idx][lru]);
 }
 
-void mem_cgroup_handle_over_high(void);
+void mem_cgroup_handle_over_high(gfp_t gfp_mask);
 
 unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg);
 
@@ -1458,7 +1458,7 @@ static inline void mem_cgroup_unlock_pages(void)
        rcu_read_unlock();
 }
 
-static inline void mem_cgroup_handle_over_high(void)
+static inline void mem_cgroup_handle_over_high(gfp_t gfp_mask)
 {
 }
 

diff --git a/include/linux/resume_user_mode.h b/include/linux/resume_user_mode.h
index 28518945444968fed623838f4028dca96736a9f7..f8f3e958e9cf2fbf0777fdbf5e3fd993c889cee3 100644 (file)
--- a/include/linux/resume_user_mode.h
+++ b/include/linux/resume_user_mode.h
@@ -55,7 +55,7 @@ static inline void resume_user_mode_work(struct pt_regs *regs)
        }
 #endif
 
-       mem_cgroup_handle_over_high();
+       mem_cgroup_handle_over_high(GFP_KERNEL);
        blkcg_maybe_throttle_current();
 
        rseq_handle_notify_resume(NULL, regs);

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a4d3282493b60461a7cb8e275db27a8638c0c4a4..d13dde2f8b56eccd7553641b1e989eeeab092acd 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2555,7 +2555,7 @@ static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
  * Scheduled by try_charge() to be executed from the userland return path
  * and reclaims memory over the high limit.
  */
-void mem_cgroup_handle_over_high(void)
+void mem_cgroup_handle_over_high(gfp_t gfp_mask)
 {
        unsigned long penalty_jiffies;
        unsigned long pflags;
@@ -2583,7 +2583,7 @@ retry_reclaim:
         */
        nr_reclaimed = reclaim_high(memcg,
                                    in_retry ? SWAP_CLUSTER_MAX : nr_pages,
-                                   GFP_KERNEL);
+                                   gfp_mask);
 
        /*
         * memory.high is breached and reclaim is unable to keep up. Throttle
@@ -2819,7 +2819,7 @@ done_restock:
        if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH &&
            !(current->flags & PF_MEMALLOC) &&
            gfpflags_allow_blocking(gfp_mask)) {
-               mem_cgroup_handle_over_high();
+               mem_cgroup_handle_over_high(gfp_mask);
        }
        return 0;
 }