From: Tejun Heo <tj@kernel.org>
To: Tao Cui <cui.tao@linux.dev>
Cc: axboe@kernel.dk, josef@toxicpanda.com, yukuai@fygo.io,
cgroups@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, Tao Cui <cuitao@kylinos.cn>
Subject: Re: [PATCH v2] block/blk-cgroup-rwstat: use data_race() for online test
Date: Mon, 3 Aug 2026 06:47:48 -1000 [thread overview]
Message-ID: <anDGNLFidOuxqy12@slm.duckdns.org> (raw)
In-Reply-To: <20260803133400.137906-1-cui.tao@linux.dev>
On Mon, Aug 03, 2026 at 09:34:00PM +0800, Tao Cui wrote:
> From: Tao Cui <cuitao@kylinos.cn>
>
> blkg_rwstat_recursive_sum() reads pos_blkg->online without the queue
> lock that its doc comment requires, since blkcg_print_blkgs() stopped
> holding it in 56cc24f59c14. Concurrent blkg_create/destroy flips
> ->online, tripping KCSAN. The race is harmless (RCU-protected, stale
> online only causes minor stat noise). Use data_race() to annotate
> the intentional lockless read.
>
> Also update the stale doc comment that still requires the queue lock.
>
> Reviewed-by: Yu Kuai <yukuai@fygo.io>
> Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
next prev parent reply other threads:[~2026-08-03 16:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-03 13:34 [PATCH v2] block/blk-cgroup-rwstat: use data_race() for online test Tao Cui
2026-08-03 16:47 ` Tejun Heo [this message]
2026-08-04 2:17 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=anDGNLFidOuxqy12@slm.duckdns.org \
--to=tj@kernel.org \
--cc=axboe@kernel.dk \
--cc=cgroups@vger.kernel.org \
--cc=cui.tao@linux.dev \
--cc=cuitao@kylinos.cn \
--cc=josef@toxicpanda.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=yukuai@fygo.io \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox