mm, memcg: Prevent memory.soft_limit_in_bytes load/store tearing
authorYue Zhao <findns94@gmail.com>
Mon, 6 Mar 2023 15:41:38 +0000 (23:41 +0800)
committerAndrew Morton <akpm@linux-foundation.org>
Tue, 28 Mar 2023 23:20:13 +0000 (16:20 -0700)
commit2178e20c24406548c97b18a2d9781d16c35b8881
tree06ab854b92d1327b115ceca93d24d6e6aa4d5916
parent17c56de6a8c9970f56375c13f8654bbcbc94c090
mm, memcg: Prevent memory.soft_limit_in_bytes load/store tearing

The knob for cgroup v1 memory controller: memory.soft_limit_in_bytes is
not protected by any locking so it can be modified while it is used.  This
is not an actual problem because races are unlikely.  But it is better to
use [READ|WRITE]_ONCE to prevent compiler from doing anything funky.

The access of memcg->soft_limit is lockless, so it can be concurrently set
at the same time as we are trying to read it.  All occurrences of
memcg->soft_limit are updated with [READ|WRITE]_ONCE.

[findns94@gmail.com: v3]
Link: https://lkml.kernel.org/r/20230308162555.14195-5-findns94@gmail.com
Link: https://lkml.kernel.org/r/20230306154138.3775-5-findns94@gmail.com
Signed-off-by: Yue Zhao <findns94@gmail.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Tang Yizhou <tangyeechou@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/memcontrol.c