From: Andrew Morton <akpm@linux-foundation.org>
To: Liu Shixin <liushixin2@huawei.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/vmstat: annotate data race for zone->free_area[order].nr_free
Date: Tue, 14 Sep 2021 21:10:27 -0700 [thread overview]
Message-ID: <20210914211027.0d612d99a94b085112ba0969@linux-foundation.org> (raw)
In-Reply-To: <20210908015606.3999871-1-liushixin2@huawei.com>
On Wed, 8 Sep 2021 09:56:06 +0800 Liu Shixin <liushixin2@huawei.com> wrote:
> KCSAN reports a data-race on v5.10 which also exists on mainline:
>
> ==================================================================
> BUG: KCSAN: data-race in extfrag_for_order+0x33/0x2d0
>
> race at unknown origin, with read to 0xffff9ee9bfffab48 of 8 bytes by task 34 on cpu 1:
> extfrag_for_order+0x33/0x2d0
> kcompactd+0x5f0/0xce0
> kthread+0x1f9/0x220
> ret_from_fork+0x22/0x30
>
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 1 PID: 34 Comm: kcompactd0 Not tainted 5.10.0+ #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> ==================================================================
>
> Access to zone->free_area[order].nr_free in extfrag_for_order()/frag_show_print()
> is lockless. That's intentional and the stats are a rough estimate anyway.
> Annotate them with data_race().
checkpatch helpfully says
WARNING: data_race without comment
#40: FILE: mm/vmstat.c:1074:
+ blocks = data_race(zone->free_area[order].nr_free);
can we please add a comment ;)
prev parent reply other threads:[~2021-09-15 4:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 1:56 Liu Shixin
2021-09-15 4:10 ` Andrew Morton [this message]
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