Hello, > 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. Hmm, I don't see how this could deadlock since we seem to take kernel lock only in do_new_mount() before calling do_kern_mount(). But you are right that taking the kernel lock with s_umount_sem looks fishy... > p.s. I found this suspected bug by the motivation from > commit 5f22ca9b13551debea77a407a8d06cd9c6f15238. From a quick look, this looks like a different matter - they have used lock_super() instead of lock_kernel() and that's used in more places. Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
