Mikhail Ukhin <mish.uxin2012@xxxxxxxxx> writes:
> 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.
>
Maybe we should update the subject msg to:
"ext4: "fix i_data_sem unlock order in ext4_ind_migrate()"
and also should add:
CC: stable@xxxxxxxxxxxxxxx
I think this should have been fixed in patch [1], but looks like it
forgot to fix the unlock order.
[1]: https://lore.kernel.org/all/1364801462-13120-1-git-send-email-dmonakhov@xxxxxxxxxx/
> Found by Linux Verification Center (linuxtesting.org) with syzkaller.
I am not sure if there is an easy reproducer. If yes, we should consider
adding it in fstests.
>
> Signed-off-by: Artem Sadovnikov <ancowi69@xxxxxxxxx>
Thanks for fixing it. With above changes to subject and CC tag, this
looks good to me. Feel free to add -
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> ---
> fs/ext4/migrate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
> index d98ac2af8199..a5e1492bbaaa 100644
> --- a/fs/ext4/migrate.c
> +++ b/fs/ext4/migrate.c
> @@ -663,8 +663,8 @@ int ext4_ind_migrate(struct inode *inode)
> if (unlikely(ret2 && !ret))
> ret = ret2;
> errout:
> - ext4_journal_stop(handle);
> up_write(&EXT4_I(inode)->i_data_sem);
> + ext4_journal_stop(handle);
> out_unlock:
> ext4_writepages_up_write(inode->i_sb, alloc_ctx);
> return ret;
> --
> 2.25.1
