mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Krystian Kaniewski <krystianmkaniewski@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ian Kent <raven@themaw.net>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Danilo Krummrich <dakr@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,
	driver-core@lists.linux.dev, autofs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	syzbot+002fb7b2d0bc53bf7e75@syzkaller.appspotmail.com
Subject: Re: [PATCH 0/2] kernfs, autofs: fix pipe lock cycles through sysfs stores
Date: Wed, 21 Oct 2026 11:48:24 -1000	[thread overview]
Message-ID: <649966b83b39fcdd25e892fc3c6732a1@kernel.org> (raw)
In-Reply-To: <cover.1792577179.git.krystianmkaniewski@gmail.com>

Hello, Krystian.

On Wed, Oct 21, 2026 at 02:51:48PM +0200, Krystian Kaniewski wrote:
> syzbot reports a lockdep cycle &pipe->mutex --> &of->mutex -->
> &sbi->pipe_mutex. splice holds a pipe mutex while it calls the write or
> read handler of a kernfs file, kernfs takes of->mutex there, and a write
> to /sys/power/resume looks up a path that can make autofs write a request
> into its daemon pipe and wait for the daemon.

This is an extremely convoluted case that isn't going to happen in any
realistic scenario, and it doesn't make sense to change the locking scheme
for it. Can we just disallow splice on /sys/power/resume instead?

Thanks.

--
tejun

      parent reply	other threads:[~2026-10-21 21:48 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-10  4:26 [syzbot] [autofs?] possible deadlock in anon_pipe_prefill_and_lock syzbot
2026-09-18 10:46 ` syzbot
2026-09-23 11:06 ` syzbot
2026-10-21 12:51 ` [PATCH 0/2] kernfs, autofs: fix pipe lock cycles through sysfs stores Krystian Kaniewski
2026-10-21 12:51   ` [PATCH 1/2] kernfs: do not hold of->mutex across sysfs ->store() Krystian Kaniewski
2026-10-21 12:51   ` [PATCH 2/2] autofs: do not wait for the daemon while splice holds a pipe Krystian Kaniewski
2026-10-21 21:48   ` Tejun Heo [this message]

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=649966b83b39fcdd25e892fc3c6732a1@kernel.org \
    --to=tj@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=autofs@vger.kernel.org \
    --cc=axboe@kernel.dk \
    --cc=brauner@kernel.org \
    --cc=dakr@kernel.org \
    --cc=driver-core@lists.linux.dev \
    --cc=gregkh@linuxfoundation.org \
    --cc=jack@suse.cz \
    --cc=krystianmkaniewski@gmail.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=rafael@kernel.org \
    --cc=raven@themaw.net \
    --cc=syzbot+002fb7b2d0bc53bf7e75@syzkaller.appspotmail.com \
    --cc=viro@zeniv.linux.org.uk \
    /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
all inboxes | Powered by JetHome®