From: =?UTF-8?B?7ZmN7IugIHNoaW4gaG9uZw==?= <hongshin@gmail.com>
Subject: BUG? a suspected deadlock bug at ext4_fill_super()
Date: Thu, 30 Jul 2009 12:09:56 +0900
Message-ID: <2014bcab0907292009y425f746aub389c406ab2dda8@mail.gmail.com>
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Hi. I found a suspected deadlock bug from ext4.

ext4_fill_super() releases and re-takes BKL while s_umount is held.
Lock ordering at the point where BKL is re-taken is s_umount-> BKL.

However, at do_remount(), locking ordering is BKL->s_umount.
Therefore, concurrent execution of do_remount() and ext4_fill_super()
may result deadlock.

Please examine this report. Thank you.


p.s. I found this suspected bug by the motivation from
       commit 5f22ca9b13551debea77a407a8d06cd9c6f15238.