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List:       linux-ext4
Subject:    Re: [PATCH v2] ext4: fix i_data_sem unlock order in ext4_ind_migrate()
From:       "Theodore Ts'o" <tytso () mit ! edu>
Date:       2024-05-09 14:51:24
Message-ID: 20240509145124.GH3620298 () mit ! edu
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On Sat, Apr 06, 2024 at 12:08:03AM +0300, Mikhail Ukhin wrote:
> Fuzzing reports a possible deadlock in jbd2_log_wait_commit.
> 
> The problem occurs in ext4_ind_migrate due to an incorrect order of
> unlocking of the journal and write semaphores - the order of unlocking
> must be the reverse of the order of locking.
> 
> Found by Linux Verification Center (linuxtesting.org) with syzkaller.
> 
> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> Signed-off-by: Artem Sadovnikov <ancowi69@gmail.com>
> Signed-off-by: Mikhail Ukhin <mish.uxin2012@yandex.ru>

Thanks.  This has been addressed by commit 00d873c17e29 ("ext4: avoid
deadlock in fs reclaim with page writeback"), with the same code
change.

						- Ted

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