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From: "Dae R. Jeong" <dae.r.jeong@kaist.ac.kr>
To: song@kernel.org
Cc: yjkwon@kaist.ac.kr, linux-raid@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: WARNING in md_ioctl
Date: Sat, 17 Oct 2020 20:06:51 +0900	[thread overview]
Message-ID: <20201017110651.GA1602260@dragonet> (raw)

Hi,

I looked into the warning "WARNING in md_ioctl" found by Syzkaller.
(https://syzkaller.appspot.com/bug?id=fbf9eaea2e65bfcabb4e2750c3ab0892867edea1)
I suspect that it is caused by a race between two concurrenct ioctl()s as belows.

CPU1 (md_ioctl())                          CPU2 (md_ioctl())
------                                     ------
set_bit(MD_CLOSING, &mddev->flags);
did_set_md_closing = true;
                                           WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags));

if(did_set_md_closing)
    clear_bit(MD_CLOSING, &mddev->flags);

If the above is correct, this warning is introduced
in the commit 065e519e("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop").
Could you please take a look into this?

Best regards,
Dae R. Jeong



             reply	other threads:[~2020-10-17 11:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-17 11:06 Dae R. Jeong [this message]
2020-10-19  6:18 ` WARNING in md_ioctl Song Liu
2020-10-19  7:03   ` Dae R. Jeong
2020-10-21  5:28     ` Song Liu
2020-10-22  0:24       ` Dae R. Jeong
  -- strict thread matches above, loose matches on Subject: below --
2018-04-30  1:00 syzbot
2019-11-25 22:37 ` syzbot
2019-11-26  8:42   ` Daniel Vetter

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