linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tejun Heo <tj@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Dmitry Vyukov <dvyukov@google.com>, Jens Axboe <axboe@kernel.dk>,
	syzbot <syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>,
	linux-block@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] bdi: Fix another oops in wb_workfn()
Date: Mon, 11 Jun 2018 10:20:53 -0700	[thread overview]
Message-ID: <20180611172053.GR1351649@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180611162920.mwapvuqotvhkntt3@quack2.suse.cz>

Hello,

On Mon, Jun 11, 2018 at 06:29:20PM +0200, Jan Kara wrote:
> > Would something like the following work or am I missing the point
> > entirely?
> 
> I was pondering the same solution for a while but I think it won't work.
> The problem is that e.g. wb_memcg_offline() could have already removed
> wb from the radix tree but it is still pending in bdi->wb_list
> (wb_shutdown() has not run yet) and so we'd drop reference we didn't get.

Yeah, right, so the root cause is that we're walking the wb_list while
holding lock and expecting the object to stay there even after lock is
released.  Hmm... we can use a mutex to synchronize the two
destruction paths.  It's not like they're hot paths anyway.

Thanks.

-- 
tejun

  reply	other threads:[~2018-06-11 17:20 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-26  9:15 general protection fault in wb_workfn (2) syzbot
2018-05-27  0:47 ` Tetsuo Handa
2018-05-27  2:21   ` [PATCH] bdi: Fix another oops in wb_workfn() Tetsuo Handa
2018-05-27  2:36     ` Tejun Heo
2018-05-28 13:35   ` general protection fault in wb_workfn (2) Jan Kara
2018-05-30 16:00     ` Tetsuo Handa
2018-05-31 11:42       ` Jan Kara
2018-05-31 13:19         ` Tetsuo Handa
2018-05-31 13:42           ` Jan Kara
2018-05-31 16:56             ` Jens Axboe
2018-06-05 13:45               ` Tetsuo Handa
2018-06-07 18:46                 ` Dmitry Vyukov
2018-06-08  2:31                   ` Tetsuo Handa
2018-06-08 14:45                     ` Dmitry Vyukov
2018-06-08 15:16                       ` Dmitry Vyukov
2018-06-08 16:53                         ` Dmitry Vyukov
2018-06-08 17:14                           ` Dmitry Vyukov
2018-06-09  5:30                             ` Tetsuo Handa
2018-06-09 14:00                               ` [PATCH] bdi: Fix another oops in wb_workfn() Tetsuo Handa
2018-06-11  9:12                                 ` Jan Kara
2018-06-11 16:01                                   ` Tejun Heo
2018-06-11 16:29                                     ` Jan Kara
2018-06-11 17:20                                       ` Tejun Heo [this message]
2018-06-12 15:57                                         ` Jan Kara
2018-06-13 10:43                                           ` Tetsuo Handa
2018-06-13 11:51                                             ` Tetsuo Handa
2018-06-13 14:06                                             ` Linus Torvalds
2018-06-13 14:46                                             ` Jan Kara
2018-06-13 14:55                                               ` Linus Torvalds
2018-06-13 16:20                                               ` Tetsuo Handa
2018-06-13 16:25                                                 ` Linus Torvalds
2018-06-13 16:45                                                   ` Jan Kara
2018-06-13 21:04                                                     ` Tetsuo Handa
2018-06-14 10:11                                                       ` Jan Kara
2018-06-13 14:33                                           ` Tejun Heo
2018-06-15 12:06                                             ` Jan Kara
2018-06-18 12:27                                               ` Jan Kara
2018-06-01  2:30             ` general protection fault in wb_workfn (2) Dave Chinner

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=20180611172053.GR1351649@devbig577.frc2.facebook.com \
    --to=tj@kernel.org \
    --cc=axboe@kernel.dk \
    --cc=david@fromorbit.com \
    --cc=dvyukov@google.com \
    --cc=jack@suse.cz \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=torvalds@linux-foundation.org \
    --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).