Re: [PATCH] loop: drop loop_ctl_mutex around del_gendisk() in loop_remove()
From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Date: 2021-06-15 05:30:54
Found that commit 990e78116d38059c ("block: loop: fix deadlock between open and remove") went to 5.13-rc6.
#syz fix: block: loop: fix deadlock between open and remove
Now syzbot is reporting
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(nbd_index_mutex);
lock(&bdev->bd_mutex);
lock(nbd_index_mutex);
lock(&bdev->bd_mutex);
at https://syzkaller.appspot.com/text?tag=CrashReport&x=11b8a5bbd00000 .