From: Chris Down <chris@chrisdown.name>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH 6/6] mm, memcg: Prevent mem_cgroup_protected store tearing
Date: Thu, 12 Mar 2020 17:33:16 +0000 [thread overview]
Message-ID: <d1e9fbc0379fe8db475d82c8b6fbe048876e12ae.1584034301.git.chris@chrisdown.name> (raw)
In-Reply-To: <cover.1584034301.git.chris@chrisdown.name>
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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-mm@kvack.org
Cc: cgroups@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com
---
mm/memcontrol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 57048a38c75d..e9af606238ab 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6301,8 +6301,8 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
}
exit:
- memcg->memory.emin = emin;
- memcg->memory.elow = elow;
+ WRITE_ONCE(memcg->memory.emin, emin);
+ WRITE_ONCE(memcg->memory.elow, elow);
if (usage <= emin)
return MEMCG_PROT_MIN;
--
2.25.1
next prev parent reply other threads:[~2020-03-12 17:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 17:32 [PATCH 0/6] mm, memcg: cgroup v2 tunable load/store tearing fixes Chris Down
2020-03-12 17:32 ` [PATCH 1/6] mm, memcg: Prevent memory.high load/store tearing Chris Down
2020-03-16 14:54 ` Michal Hocko
2020-03-12 17:32 ` [PATCH 2/6] mm, memcg: Prevent memory.max load tearing Chris Down
2020-03-16 14:56 ` Michal Hocko
2020-03-12 17:33 ` [PATCH 3/6] mm, memcg: Prevent memory.low load/store tearing Chris Down
2020-03-16 14:57 ` Michal Hocko
2020-06-12 17:03 ` Michal Koutný
2020-06-12 17:13 ` Chris Down
2020-03-12 17:33 ` [PATCH 4/6] mm, memcg: Prevent memory.min " Chris Down
2020-03-16 14:58 ` Michal Hocko
2020-03-12 17:33 ` [PATCH 5/6] mm, memcg: Prevent memory.swap.max load tearing Chris Down
2020-03-16 14:58 ` Michal Hocko
2020-03-12 17:33 ` Chris Down [this message]
2020-03-16 14:59 ` [PATCH 6/6] mm, memcg: Prevent mem_cgroup_protected store tearing Michal Hocko
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