From: Petr Mladek <pmladek@suse.com>
To: Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
John Ogness <john.ogness@linutronix.de>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
linux-kernel@vger.kernel.org,
syzbot+8324b8fd984b86905a66@syzkaller.appspotmail.com
Subject: Re: [PATCH v2] printk: annotate the intentional data race on the data block id
Date: Tue, 27 Oct 2026 16:24:39 +0100 [thread overview]
Message-ID: <auDCN1eYK3dshG4f@pathway.suse.cz> (raw)
In-Reply-To: <20261012120341.12423-1-ngocthang2710.1999@gmail.com>
On Mon 2026-10-12 19:03:39, Nguyen Ngoc Thang wrote:
> data_alloc() stores the descriptor ID into a newly reserved data block
> while data_make_reusable(), running from data_push_tail() on another CPU,
> may still be loading the ID from the same area. The ringbuffer allows
> this race: a stale or garbage ID simply fails the descriptor lookup or
> the blk_lpos check. KCSAN nevertheless reports it.
>
> Annotate the accesses with data_race() instead of READ_ONCE()/WRITE_ONCE(),
> which would needlessly restrict compiler optimizations for a race that is
> allowed by design. No functional change.
>
> Reported-by: syzbot+8324b8fd984b86905a66@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=8324b8fd984b86905a66
> Fixes: 896fbe20b4e2 ("printk: use the lockless ringbuffer")
> Signed-off-by: Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>
Looks good to me:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
next prev parent reply other threads:[~2026-10-27 15:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 12:03 [PATCH v2] printk: annotate the intentional data race on the data block id Nguyen Ngoc Thang
2026-10-12 12:34 ` John Ogness
2026-10-27 15:24 ` Petr Mladek [this message]
2026-10-27 15:47 ` Petr Mladek
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=auDCN1eYK3dshG4f@pathway.suse.cz \
--to=pmladek@suse.com \
--cc=john.ogness@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=ngocthang2710.1999@gmail.com \
--cc=rostedt@goodmis.org \
--cc=senozhatsky@chromium.org \
--cc=syzbot+8324b8fd984b86905a66@syzkaller.appspotmail.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.