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From: Hao Sun <sunhao.th@gmail.com>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	cgroups@vger.kernel.org, hannes@cmpxchg.org,
	lizefan.x@bytedance.com, tj@kernel.org
Subject: Re: KCSAN: data-race in cgroup_rstat_flush_locked / cgroup_rstat_updated
Date: Sat, 18 Sep 2021 09:27:08 +0800	[thread overview]
Message-ID: <CACkBjsZnp8Kf26tR3anbcLQNiMJ9=bqYMJ66tKBvXO6tkV3qyw@mail.gmail.com> (raw)
In-Reply-To: <20210917164123.GA13346@blackbody.suse.cz>

Hi Michal,

Michal Koutný <mkoutny@suse.com> 于2021年9月18日周六 上午12:41写道：
>
> Hello Hao.
>
> On Thu, Sep 16, 2021 at 09:53:55PM +0800, Hao Sun <sunhao.th@gmail.com> wrote:
> > KCSAN reported the following data race during the kernel booting when
> > using Healer to fuzz the latest Linux kernel.
> > [...]
> >  cgroup_rstat_cpu_pop_updated kernel/cgroup/rstat.c:139 [inline]
> >  [...]
> >  cgroup_rstat_updated+0x53/0x1b0 kernel/cgroup/rstat.c:38
>
> FWIW, it's a "safe" race between updaters and flushers (possibly
> missing the latest update(s)). This is expected as explained in
> cgroup_rstat_updated() comment.
>

Would it be better to add a `data_race` macro to the corresponding
location so that the false report can be disabled?
See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/memory-model/Documentation/access-marking.txt#n58
for more details.
Currently, fuzzer can not test the kernel with KCSAN enabled for a
long time, because cgroups setup is the basic step before executing
any test case.

Regards
Hao

  reply	other threads:[~2021-09-18  1:27 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-16 13:53 KCSAN: data-race in cgroup_rstat_flush_locked / cgroup_rstat_updated Hao Sun
2021-09-17 16:41 ` Michal Koutný
2021-09-18  1:27   ` Hao Sun [this message]
2021-09-20 18:09     ` Michal Koutný

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