From: "Paul E. McKenney" <paulmck@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>,
Thomas Gleixner <tglx@linutronix.de>,
Stephen Boyd <sboyd@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
syzbot <syzbot+d6c75f383e01426a40b4@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
syzkaller-bugs@googlegroups.com, Waiman Long <llong@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [syzbot] WARNING in __init_work
Date: Mon, 20 Sep 2021 05:54:24 -0700 [thread overview]
Message-ID: <20210920125424.GG880162@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <20210920124557.GA18317@lst.de>
On Mon, Sep 20, 2021 at 02:45:57PM +0200, Christoph Hellwig wrote:
> On Mon, Sep 20, 2021 at 05:38:59AM -0700, Paul E. McKenney wrote:
> > > Well, the block code already does a bdi_unregister in del_gendisk.
> > > So if we end up freeing the whole device bdev with a registered bdi
> > > something is badly going wrong. Unfortunately the log in this report
> > > isn't much help on how we got there. IIRC syzbot will eventually spew
> > > out a reproducer, so it might be worth to wait for that.
> >
> > If it does turn out that you need to block in an RCU callback,
> > queue_rcu_work() can be helpful. This schedules a workqueue from the RCU
> > callback, allowing the function passed to the preceding INIT_RCU_WORK()
> > to block.
>
> In this case we really should not block here. The problem is that
> we are hitting the strange bdi auto-unregister misfeature due to a bug
> elsewhere. Which reminds that I have a patch series to remove this
> auto unregistration which I need to bring bag once this is fixed.
>
> That being said queue_rcu_work would have been really useful in a few
> places I touched in that past.
Glad it helped elsewhere and apologies for the noise here!
Thanx, Paul
next prev parent reply other threads:[~2021-09-20 12:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000423e0a05cc0ba2c4@google.com>
[not found] ` <20210915161457.95ad5c9470efc70196d48410@linux-foundation.org>
[not found] ` <163175937144.763609.2073508754264771910@swboyd.mtv.corp.google.com>
2021-09-19 12:41 ` [syzbot] WARNING in __init_work Thomas Gleixner
2021-09-20 4:03 ` Dave Chinner
2021-09-20 12:28 ` Christoph Hellwig
2021-09-20 12:38 ` Paul E. McKenney
2021-09-20 12:45 ` Christoph Hellwig
2021-09-20 12:54 ` Paul E. McKenney [this message]
[not found] ` <163224949689.3714697.17466968510780664239@swboyd.mtv.corp.google.com>
2021-09-21 20:19 ` Thomas Gleixner
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=20210920125424.GG880162@paulmck-ThinkPad-P17-Gen-1 \
--to=paulmck@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=david@fromorbit.com \
--cc=hch@lst.de \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=llong@redhat.com \
--cc=sboyd@kernel.org \
--cc=syzbot+d6c75f383e01426a40b4@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tglx@linutronix.de \
--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;
as well as URLs for NNTP newsgroup(s).