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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Jan Kara <jack@suse.cz>, Tejun Heo <tj@kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>, Jens Axboe <axboe@kernel.dk>,
	syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>,
	linux-block <linux-block@vger.kernel.org>
Subject: Re: [PATCH] bdi: Fix another oops in wb_workfn()
Date: Wed, 13 Jun 2018 09:25:03 -0700	[thread overview]
Message-ID: <CA+55aFx=CwNCg08HUeyYWc-WWuPkQBXVJDvHfrBjraTy-3MRWQ@mail.gmail.com> (raw)
In-Reply-To: <7f4ae045-dfe4-6677-7418-f6f60b6c26f1@i-love.sakura.ne.jp>

On Wed, Jun 13, 2018 at 9:21 AM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Since multiple addresses share bit_wait_table[256], isn't it possible that
> cgwb_start_shutdown() prematurely returns false due to wake_up_bit() by
> hash-conflicting addresses (i.e. not limited to clear_and_wake_up_bit() from
> wb_shutdown())? I think that we cannot be sure without confirming that
> test_bit(WB_shutting_down, &wb->state) == false after returning from schedule().

Right.

That's _always_ true, btw. Something else entirely could have woken
you up. TASK_UNINTERRUPTIBLE does not mean "nothing else wakes me", it
just means "_signals_ don't wake me".

So every single sleep always needs to be in a loop. Always.

              Linus

  reply	other threads:[~2018-06-13 16:25 UTC|newest]

Thread overview: 49+ 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
2018-05-27  4:43       ` Tetsuo Handa
2018-05-29 13:46         ` Tejun Heo
2018-05-28 13:35   ` general protection fault in wb_workfn (2) Jan Kara
2018-05-30 16:00     ` Tetsuo Handa
2018-05-30 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
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 14:46                                               ` Jan Kara
2018-06-13 14:55                                               ` Linus Torvalds
2018-06-13 16:20                                               ` Tetsuo Handa
2018-06-13 16:25                                                 ` Linus Torvalds [this message]
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
2018-06-15 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
2018-06-18 13:46 [PATCH] bdi: Fix another oops in wb_workfn() Jan Kara
2018-06-18 14:38 ` Tetsuo Handa
2018-06-19  8:41   ` Jan Kara
2018-06-18 17:40 ` Tejun Heo
2018-06-22  8:52   ` Jan Kara
2018-06-22 18:08     ` Jens Axboe

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