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From: Yue Zhao <findns94@gmail.com>
To: linux-mm@kvack.org
Cc: akpm@linux-foundation.org, roman.gushchin@linux.dev,
	hannes@cmpxchg.org, mhocko@kernel.org, shakeelb@google.com,
	muchun.song@linux.dev, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, Yue Zhao <findns94@gmail.com>
Subject: [PATCH] mm: change memcg->oom_group access with atomic operations
Date: Mon, 20 Feb 2023 23:16:38 +0800	[thread overview]
Message-ID: <20230220151638.1371-1-findns94@gmail.com> (raw)

The knob for cgroup v2 memory controller: memory.oom.group
will be read and written simultaneously by user space
programs, thus we'd better change memcg->oom_group access
with atomic operations to avoid concurrency problems.

Signed-off-by: Yue Zhao <findns94@gmail.com>
---
 mm/memcontrol.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 73afff8062f9..e4695fb80bda 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2057,7 +2057,7 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
 	 * highest-level memory cgroup with oom.group set.
 	 */
 	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
-		if (memcg->oom_group)
+		if (READ_ONCE(memcg->oom_group))
 			oom_group = memcg;
 
 		if (memcg == oom_domain)
@@ -6569,7 +6569,7 @@ static int memory_oom_group_show(struct seq_file *m, void *v)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
 
-	seq_printf(m, "%d\n", memcg->oom_group);
+	seq_printf(m, "%d\n", READ_ONCE(memcg->oom_group));
 
 	return 0;
 }
@@ -6591,7 +6591,7 @@ static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
 	if (oom_group != 0 && oom_group != 1)
 		return -EINVAL;
 
-	memcg->oom_group = oom_group;
+	WRITE_ONCE(memcg->oom_group, oom_group);
 
 	return nbytes;
 }
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: Yue Zhao <findns94-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
Cc: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
	roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org,
	hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org,
	mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
	muchun.song-fxUVXftIFDnyG1zEObXtfA@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Yue Zhao <findns94-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: [PATCH] mm: change memcg->oom_group access with atomic operations
Date: Mon, 20 Feb 2023 23:16:38 +0800	[thread overview]
Message-ID: <20230220151638.1371-1-findns94@gmail.com> (raw)

The knob for cgroup v2 memory controller: memory.oom.group
will be read and written simultaneously by user space
programs, thus we'd better change memcg->oom_group access
with atomic operations to avoid concurrency problems.

Signed-off-by: Yue Zhao <findns94-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 mm/memcontrol.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 73afff8062f9..e4695fb80bda 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2057,7 +2057,7 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
 	 * highest-level memory cgroup with oom.group set.
 	 */
 	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
-		if (memcg->oom_group)
+		if (READ_ONCE(memcg->oom_group))
 			oom_group = memcg;
 
 		if (memcg == oom_domain)
@@ -6569,7 +6569,7 @@ static int memory_oom_group_show(struct seq_file *m, void *v)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
 
-	seq_printf(m, "%d\n", memcg->oom_group);
+	seq_printf(m, "%d\n", READ_ONCE(memcg->oom_group));
 
 	return 0;
 }
@@ -6591,7 +6591,7 @@ static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
 	if (oom_group != 0 && oom_group != 1)
 		return -EINVAL;
 
-	memcg->oom_group = oom_group;
+	WRITE_ONCE(memcg->oom_group, oom_group);
 
 	return nbytes;
 }
-- 
2.17.1


             reply	other threads:[~2023-02-20 15:17 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-20 15:16 Yue Zhao [this message]
2023-02-20 15:16 ` [PATCH] mm: change memcg->oom_group access with atomic operations Yue Zhao
2023-02-20 21:09 ` Roman Gushchin
2023-02-20 21:09   ` Roman Gushchin
2023-02-20 23:06   ` Shakeel Butt
2023-02-20 23:06     ` Shakeel Butt
2023-02-21  5:17     ` Roman Gushchin
2023-02-21  5:17       ` Roman Gushchin
2023-02-21  6:52       ` Shakeel Butt
2023-02-21  6:52         ` Shakeel Butt
2023-02-21 13:51         ` Matthew Wilcox
2023-02-21 13:51           ` Matthew Wilcox
2023-02-21 16:56           ` Shakeel Butt
2023-02-21 16:56             ` Shakeel Butt
2023-02-21 18:23             ` Paul E. McKenney
2023-02-21 18:23               ` Paul E. McKenney
2023-02-21 22:23               ` Roman Gushchin
2023-02-21 22:23                 ` Roman Gushchin
2023-02-21 22:38                 ` Paul E. McKenney
2023-02-21 22:38                   ` Paul E. McKenney
2023-02-21 23:13                   ` Shakeel Butt
2023-02-21 23:13                     ` Shakeel Butt
2023-02-21 23:38                     ` Paul E. McKenney
2023-02-21 23:38                       ` Paul E. McKenney
2023-02-21 23:57                       ` Roman Gushchin
2023-02-21 23:57                         ` Roman Gushchin
2023-02-22  0:37                         ` Paul E. McKenney
2023-02-22  0:37                           ` Paul E. McKenney
2023-02-22  4:28                           ` Roman Gushchin
2023-02-21 17:47           ` Roman Gushchin
2023-02-21 17:47             ` Roman Gushchin
2023-02-21 18:15             ` Shakeel Butt
2023-02-21 18:15               ` Shakeel Butt
2023-02-21 18:18             ` Matthew Wilcox
2023-02-21 18:18               ` Matthew Wilcox
2023-02-22  9:01           ` David Laight
2023-02-21 17:00         ` Martin Zhao
2023-02-21 17:00           ` Martin Zhao
2023-02-21  7:22       ` Muchun Song
2023-02-21 17:48         ` Roman Gushchin
2023-02-21 17:48           ` Roman Gushchin
2023-02-21 17:00       ` Martin Zhao
2023-02-21 17:00         ` Martin Zhao
2023-02-21 18:02         ` Roman Gushchin
2023-02-21 18:02           ` Roman Gushchin
2023-02-21  8:26     ` Michal Hocko
2023-02-21  8:26       ` Michal Hocko
2023-02-21 17:00       ` Martin Zhao
2023-02-21 17:00         ` Martin Zhao

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