diff options
| author | Chris Down <chris@chrisdown.name> | 2020-04-01 21:07:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 09:35:29 -0700 |
| commit | b3a7822e5e7513006d74946a69bfbbc8d8472e90 (patch) | |
| tree | 3eb11a32c0ab0fd8cfcb357a08e54f293a57cee7 | |
| parent | 32d087cdd9a1ff179177513a8b5d34bec2f54e62 (diff) | |
| download | unicode-b3a7822e5e7513006d74946a69bfbbc8d8472e90.tar.gz | |
mm, memcg: prevent mem_cgroup_protected store tearing
The read side of this is all protected, but we can still tear if multiple
iterations of mem_cgroup_protected are going at the same time.
There's some intentional racing in mem_cgroup_protected which is ok, but
load/store tearing should be avoided.
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/d1e9fbc0379fe8db475d82c8b6fbe048876e12ae.1584034301.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/memcontrol.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1cd944c2a734b..a96d9015ff734 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6396,14 +6396,14 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, parent_usage = page_counter_read(&parent->memory); - memcg->memory.emin = effective_protection(usage, parent_usage, + WRITE_ONCE(memcg->memory.emin, effective_protection(usage, parent_usage, READ_ONCE(memcg->memory.min), READ_ONCE(parent->memory.emin), - atomic_long_read(&parent->memory.children_min_usage)); + atomic_long_read(&parent->memory.children_min_usage))); - memcg->memory.elow = effective_protection(usage, parent_usage, + WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage, memcg->memory.low, READ_ONCE(parent->memory.elow), - atomic_long_read(&parent->memory.children_low_usage)); + atomic_long_read(&parent->memory.children_low_usage))); out: if (usage <= memcg->memory.emin) |