On Sun, Apr 30, 2023 at 12:34:00PM -0400, Theodore Ts'o wrote: > On Tue, Apr 11, 2023 at 02:10:19PM +0200, Jan Kara wrote: > > When we enable MMP in ext4_multi_mount_protect() during mount or > > remount, we end up calling sb_start_write() from write_mmp_block(). This > > triggers lockdep warning because freeze protection ranks above s_umount > > semaphore we are holding during mount / remount. The problem is harmless > > because we are guaranteed the filesystem is not frozen during mount / > > remount but still let's fix the warning by not grabbing freeze > > protection from ext4_multi_mount_protect(). > > > > Reported-by: syzbot+aacb82fca60873422114@xxxxxxxxxxxxxxxxxxxxxxxxx > > I believe this is the wrong Reported-by. The correct one looks like > it should be: ... By the way, I noticed because I was browsing the syzbot dashboard for the ext4 subsystem, and the Syzbot page for "possible deadlock in sys_quotactl_fd"[1], I saw a discussion link to lore for the patch "[PATCH] ext4: Fix lockdep warning when enabling MMP", and said, "Hmm.... that looks wrong." :-) [1] https://syzkaller.appspot.com/bug?id=1680b22e0e5eb9245a6faff10221ed76b8c5eb81 Anyway, thanks to the Syzbot team for adding Disscusion links to the Syzbot pages. It makes it a lot easier to find discussions related to a particular issue. Note: you can also manually add a thread to the discussions section by simply adding a CC to the Reported-by link for the particular issue (for example, "Cc: syzbot+aacb82fca60873422114@xxxxxxxxxxxxxxxxxxxxxxxxx"). Cheers, - Ted
