All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dmitry Vyukov <dvyukov@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	syzbot <syzbot+7b2866454055e43c21e5@syzkaller.appspotmail.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: INFO: task hung in __sb_start_write
Date: Mon, 11 Jun 2018 09:39:07 +0200	[thread overview]
Message-ID: <CACT4Y+Zyf2e_K0oRJ5oRj3WYWpf-t=V=RKHYcdqujF3s9PJL_w@mail.gmail.com> (raw)
In-Reply-To: <20180611073038.GK12217@hirez.programming.kicks-ass.net>

On Mon, Jun 11, 2018 at 9:30 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Sun, Jun 10, 2018 at 11:47:56PM +0900, Tetsuo Handa wrote:
>
>> This looks quite strange that nobody is holding percpu_rw_semaphore for
>> write but everybody is stuck trying to hold it for read. (Since there
>> is no "X locks held by ..." line without followup "#0:" line, there is
>> no possibility that somebody is in TASK_RUNNING state while holding
>> percpu_rw_semaphore for write.)
>>
>> I feel that either API has a bug or API usage is wrong.
>> Any idea for debugging this?
>
> Look at percpu_rwsem_release() and usage. The whole fs freezer thing is
> magic.

Do you mean that we froze fs? We tried to never-ever issue
ioctl(FIFREEZE) during fuzzing. Are there other ways to do this?

  reply	other threads:[~2018-06-11  7:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-03 10:17 syzbot
2018-06-10 14:47 ` Tetsuo Handa
2018-06-11  7:30   ` Peter Zijlstra
2018-06-11  7:39     ` Dmitry Vyukov [this message]
2018-06-14 10:33       ` Tetsuo Handa
2018-06-14 10:33         ` Tetsuo Handa
2018-06-15  9:19         ` Dmitry Vyukov
2018-06-15 19:40           ` Tetsuo Handa
2018-06-19 11:10             ` Tetsuo Handa
2018-06-19 11:47               ` Dmitry Vyukov
2018-06-19 13:00                 ` Tetsuo Handa
2018-07-11 11:13               ` Tetsuo Handa
2018-07-13 10:38                 ` Tetsuo Handa

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='CACT4Y+Zyf2e_K0oRJ5oRj3WYWpf-t=V=RKHYcdqujF3s9PJL_w@mail.gmail.com' \
    --to=dvyukov@google.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=peterz@infradead.org \
    --cc=syzbot+7b2866454055e43c21e5@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=viro@zeniv.linux.org.uk \
    --cc=will.deacon@arm.com \
    --subject='Re: INFO: task hung in __sb_start_write' \
    /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

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.