linux-kernel - Re: KCSAN: data-race in cgroup_rstat_flush_locked / cgroup_rstat

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Message-ID: <20210917164123.GA13346@blackbody.suse.cz>
Date:   Fri, 17 Sep 2021 18:41:23 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Hao Sun <sunhao.th@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        cgroups@...r.kernel.org, hannes@...xchg.org,
        lizefan.x@...edance.com, tj@...nel.org
Subject: Re: KCSAN: data-race in cgroup_rstat_flush_locked /
 cgroup_rstat_updated

Hello Hao.

On Thu, Sep 16, 2021 at 09:53:55PM +0800, Hao Sun <sunhao.th@...il.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.

Michal