From: Shakeel Butt <shakeelb@google.com>
To: Roman Gushchin <roman.gushchin@linux.dev>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Muchun Song <muchun.song@linux.dev>,
linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
Yosry Ahmed <yosryahmed@google.com>
Subject: Re: [PATCH v2 2/2] mm: memcg: use READ_ONCE()/WRITE_ONCE() to access stock->cached
Date: Wed, 3 May 2023 17:06:51 +0000 [thread overview]
Message-ID: <20230503170651.cw5omegmm3piumxf@google.com> (raw)
In-Reply-To: <20230502160839.361544-2-roman.gushchin@linux.dev>
On Tue, May 02, 2023 at 09:08:39AM -0700, Roman Gushchin wrote:
> A memcg pointer in the percpu stock can be accessed by drain_all_stock()
> from another cpu in a lockless way.
> In theory it might lead to an issue, similar to the one which has been
> discovered with stock->cached_objcg, where the pointer was zeroed
> between the check for being NULL and dereferencing.
> In this case the issue is unlikely a real problem, but to make it
> bulletproof and similar to stock->cached_objcg, let's annotate all
> accesses to stock->cached with READ_ONCE()/WTRITE_ONCE().
>
> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Yosry Ahmed <yosryahmed@google.com>
> Cc: Shakeel Butt <shakeelb@google.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
next prev parent reply other threads:[~2023-05-03 17:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-02 16:08 [PATCH v2 1/2] mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() Roman Gushchin
2023-05-02 16:08 ` [PATCH v2 2/2] mm: memcg: use READ_ONCE()/WRITE_ONCE() to access stock->cached Roman Gushchin
2023-05-02 20:21 ` Yosry Ahmed
2023-05-03 17:06 ` Shakeel Butt [this message]
2023-05-02 20:15 ` [PATCH v2 1/2] mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() Yosry Ahmed
2023-05-02 21:38 ` Roman Gushchin
2023-05-02 22:10 ` Yosry Ahmed
2023-05-03 17:03 ` Shakeel Butt
2023-05-03 8:05 ` Dmitry Vyukov
2023-05-03 17:04 ` Shakeel Butt
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