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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Andrea Arcangeli <aarcange@redhat.com>,
	syzbot <syzbot+96cc7aba7e969b1d305c@syzkaller.appspotmail.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH] pipe: make pipe_release() deferrable.
Date: Sat, 22 Aug 2020 09:30:25 -0700	[thread overview]
Message-ID: <CAADWXX-wpVR5Y1Z=BH5QnMjbsGbkQT__r4D2zCFFVycMDELxOQ@mail.gmail.com> (raw)
In-Reply-To: <7ba35ca4-13c1-caa3-0655-50d328304462@i-love.sakura.ne.jp>

On Fri, Aug 21, 2020 at 9:35 PM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Therefore, this patch tries to convert __pipe_lock() in pipe_release() to
> killable, by deferring to a workqueue context when __pipe_lock_killable()
> failed.

I don't think this is an improvement.

If somebody can delay the pipe unlock arbitrarily, you've now turned a
user-visible blocking operation into blocking a workqueue instead. So
it's still there, and now it possibly is much worse and blocks
system_wq instead.

                Linus

  reply	other threads:[~2020-08-22 16:30 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01  8:45 INFO: task hung in pipe_read (2) syzbot
2020-08-01 15:29 ` Tetsuo Handa
2020-08-01 17:39   ` Linus Torvalds
2020-08-07  5:31     ` Andrea Arcangeli
2020-08-08  1:01       ` Tetsuo Handa
2020-08-10 19:29         ` Andrea Arcangeli
2020-08-13  7:00           ` Tetsuo Handa
2020-08-13 11:20             ` Tetsuo Handa
2020-08-22  4:34               ` [RFC PATCH] pipe: make pipe_release() deferrable Tetsuo Handa
2020-08-22 16:30                 ` Linus Torvalds [this message]
2020-08-23  0:21                   ` Tetsuo Handa

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