From: Shakeel Butt <shakeelb@google.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yue Zhao <findns94@gmail.com>,
linux-mm@kvack.org, akpm@linux-foundation.org,
hannes@cmpxchg.org, mhocko@kernel.org, muchun.song@linux.dev,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: change memcg->oom_group access with atomic operations
Date: Mon, 20 Feb 2023 23:06:24 +0000 [thread overview]
Message-ID: <20230220230624.lkobqeagycx7bi7p@google.com> (raw)
In-Reply-To: <Y/PhmEPc/qYeZ52T@P9FQF9L96D>
On Mon, Feb 20, 2023 at 01:09:44PM -0800, Roman Gushchin wrote:
> On Mon, Feb 20, 2023 at 11:16:38PM +0800, Yue Zhao wrote:
> > 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>
>
> Hi Yue!
>
> I'm curious, have any seen any real issues which your patch is solving?
> Can you, please, provide a bit more details.
>
IMHO such details are not needed. oom_group is being accessed
concurrently and one of them can be a write access. At least
READ_ONCE/WRITE_ONCE is needed here. Most probably syzbot didn't
catch this race because it does not know about the memory.oom.group
interface.
next prev parent reply other threads:[~2023-02-20 23:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-20 15:16 Yue Zhao
2023-02-20 21:09 ` Roman Gushchin
2023-02-20 23:06 ` Shakeel Butt [this message]
2023-02-21 5:17 ` Roman Gushchin
2023-02-21 6:52 ` Shakeel Butt
2023-02-21 13:51 ` Matthew Wilcox
2023-02-21 16:56 ` Shakeel Butt
2023-02-21 18:23 ` Paul E. McKenney
2023-02-21 22:23 ` Roman Gushchin
2023-02-21 22:38 ` Paul E. McKenney
2023-02-21 23:13 ` Shakeel Butt
2023-02-21 23:38 ` Paul E. McKenney
2023-02-21 23:57 ` Roman Gushchin
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 18:15 ` Shakeel Butt
2023-02-21 18:18 ` Matthew Wilcox
2023-02-22 9:01 ` David Laight
2023-02-21 17:00 ` Martin Zhao
2023-02-21 7:22 ` Muchun Song
2023-02-21 17:48 ` Roman Gushchin
2023-02-21 17:00 ` Martin Zhao
2023-02-21 18:02 ` Roman Gushchin
2023-02-21 8:26 ` Michal Hocko
2023-02-21 17:00 ` Martin Zhao
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