Messages in this thread | | | From | Jia-Ju Bai <> | Subject | [BUG] fs: super: possible ABBA deadlocks in do_thaw_all_callback() and freeze_bdev() | Date | Mon, 27 Dec 2021 10:03:35 +0800 |
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Hello,
My static analysis tool reports several possible ABBA deadlocks in Linux 5.10:
do_thaw_all_callback() down_write(&sb->s_umount); --> Line 1028 (Lock A) emergency_thaw_bdev() thaw_bdev() mutex_lock(&bdev->bd_fsfreeze_mutex); --> Line 602 (Lock B)
freeze_bdev() mutex_lock(&bdev->bd_fsfreeze_mutex); --> Line 556 (Lock B) freeze_super() down_write(&sb->s_umount); --> Line 1716 (Lock A) down_write(&sb->s_umount); --> Line 1738 (Lock A) deactivate_super() down_write(&s->s_umount); --> Line 365 (Lock A)
When do_thaw_all_callback() and freeze_bdev() are concurrently executed, the deadlocks can occur.
I am not quite sure whether these possible deadlocks are real and how to fix them if them are real. Any feedback would be appreciated, thanks :)
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Best wishes, Jia-Ju Bai
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