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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Christoph Hellwig <hch@infradead.org>, Jan Kara <jack@suse.cz>
Cc: Dave Chinner <dchinner@redhat.com>,
	linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] loop: make autoclear operation asynchronous
Date: Fri, 3 Dec 2021 20:01:23 +0900	[thread overview]
Message-ID: <0291d903-0778-01ff-927f-97df2810262e@i-love.sakura.ne.jp> (raw)
In-Reply-To: <Yam+TsPF1jaKM+Am@infradead.org>

On 2021/12/03 15:50, Christoph Hellwig wrote:
> task_work_add sounds nice, but it is currently not exported which might
> be for a reason (I don't really have any experience with it).

I didn't find a reason not to export. But generally task_work_add() users
seem to implement a fallback which uses a WQ in case task_work_add() failed
(i.e. exit_task_work() was already called from do_exit()) or task_work_add()
cannot be used (e.g. the caller is a kernel thread).

I don't know if there is possibility that a kernel thread calls blkdev_put(),
but implementing the fallback path after all requires WQ. Thus, I think that
starting from WQ only and see if something breaks is fine.


  reply	other threads:[~2021-12-03 11:01 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-27  7:10 [syzbot] possible deadlock in blkdev_put (2) syzbot
2021-11-27 11:27 ` Tetsuo Handa
2021-11-28  5:32   ` Tetsuo Handa
2021-11-28  7:42     ` Tetsuo Handa
2021-11-29 10:21       ` Christoph Hellwig
2021-11-29 10:36         ` Tetsuo Handa
2021-11-29 14:13           ` Tetsuo Handa
2021-11-30 12:57           ` Christoph Hellwig
2021-12-01 14:41             ` [PATCH] loop: make autoclear operation asynchronous Tetsuo Handa
2021-12-02  7:22               ` Christoph Hellwig
2021-12-02 11:03                 ` Tetsuo Handa
2021-12-02 12:16               ` Jan Kara
2021-12-02 14:39                 ` Tetsuo Handa
2021-12-02 18:05                   ` Jan Kara
2021-12-03  6:50                     ` Christoph Hellwig
2021-12-03 11:01                       ` Tetsuo Handa [this message]
2021-12-08  9:56                         ` Tetsuo Handa
2021-12-08  5:05 ` [syzbot] possible deadlock in blkdev_put (2) syzbot
2021-12-08 11:42 ` syzbot

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