On Fri, Apr 08, 2016 at 04:21:02PM +0530, Shyam Kaushik wrote: > Hi Dave, Brian, Carlos, > > While trying to reproduce this issue I have been running into different > issues that are similar. Underlying issue remains the same when backend to > XFS is failed & we unmount XFS, we run into hung-task timeout (180-secs) > with stack like > > kernel: [14952.671131] [<ffffffffc06a5f59>] > xfs_ail_push_all_sync+0xa9/0xe0 [xfs] > kernel: [14952.671139] [<ffffffff810b26b0>] ? > prepare_to_wait_event+0x110/0x110 > kernel: [14952.671181] [<ffffffffc0690111>] xfs_unmountfs+0x61/0x1a0 > [xfs] > > while running trace-events, XFS ail push keeps looping around > > xfsaild/dm-10-21143 [001] ...2 17878.555133: xfs_ilock_nowait: dev > 253:10 ino 0x0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-21143 [001] ...2 17878.555138: xfs_iunlock: dev 253:10 > ino 0x0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-21143 [001] ...2 17878.555138: xfs_ail_push: dev 253:10 > lip 0xffff880031f6ae40 lsn 1/73448 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-21143 [001] ...2 17878.605136: xfs_ilock_nowait: dev > 253:10 ino 0x0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-21143 [001] ...2 17878.605141: xfs_iunlock: dev 253:10 > ino 0x0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-21143 [001] ...2 17878.605142: xfs_ail_push: dev 253:10 > lip 0xffff880031f6ae40 lsn 1/73448 type XFS_LI_INODE flags IN_AIL > > observe ino==0x0 (its a freed inode) but the corresponding lip stays with > xfsaild push. I had run a systemtap when this problem happened & the > following keeps repeating. > That's interesting, and looks different from the original report in terms of the inode number being cleared. The original report looks like it has a valid inode and there's some problematic sequence where it's not being removed from the AIL in the event of errors. I think at this point we know that XFS attempts to retry these I/Os indefinitely. Dave has outstanding patches to deal with this issue. The question Dave raised above was whether the filesystem shut down, and if not, why (as a failed log I/O should cause a shutdown)? Carlos was looking into this it appears... > xfs_inode_item_push() - inode:0xffff88003d8ca000 m_flags:0x420118 > flags:0x1 > xfs_iflush() - inode:ffff88003d8ca000 aborting for forced shutdown > xfs_iflush_abort() - iip:0x0 > > xfs_inode_item_push() is doing xfs_iflush() but it sees FS_SHUTDOWN flag > marked & does an xfs_iflush_abort().xfs_iflush_abort() sees i_itemp==NULL > on the lip & doesn't do anything. So we have this stale lip that is not > associated to inode anymore that keeps xfs_ail_push_all_sync() busy. > > On few other occurrences, i have had NULL pointer/dereference or other > sorts of crashes at this line > > xfsaild_push() > lock_result = lip->li_ops->iop_push(lip, > &ailp->xa_buf_list); > > with debug prints, in one of the occurrence lip->li_ops was NULL & in > another lip->li_ops was pointing to a bad pointer that subsequent > dereference crashed it. This also indicates that a bad/freed lip was > inserted that xfsaild_push() is working. > > I hit upon Dave's patch "xfs: xfs_inode_free() isn't RCU safe" & realized > that this could explain the above issue where a lip that has been freed is > wrongly referenced & later we could even have the inode disconnected. What > do you think? > > In any case I uploaded the full xfs trace events before this issue started > & till the end. It is at > https://www.dropbox.com/s/21qstz4ld1gn8yi/xfs_trace_pipe.gz?dl=0 > It seems like it could be related. I didn't catch anything obvious from the trace, but there's a lot of data there. The RCU-unsafe issue was difficult to track down without instrumentation.. I'm not sure that will be evident from the trace. The best thing to do wrt to that might be to try with Dave's patches, as that so far appears to address the problem. (In fact, it might be worth it to try Dave's shutdown on umount patch he referred to up-thread to address the original problem as well). Brian > Pls let me know. Thanks. > > --Shyam > > -----Original Message----- > From: Shyam Kaushik [mailto:shyam@xxxxxxxxxxxxxxxxx] > Sent: 23 March 2016 15:23 > To: 'Brian Foster' > Cc: 'xfs@xxxxxxxxxxx'; Alex Lyakas > Subject: RE: XFS hung task in xfs_ail_push_all_sync() when unmounting FS > after disk failure/recovery > > Hi Carlos, > > w.r.t. your question below > > >>> Shyam, after you reconnected the disks, the messages about failed > async metadata > >>> writes stops to be logged? > > After I reconnect the disks, messages about failed async metadata writes > stops to be logged. But the key thing is messages like > > XFS (dm-29): xfs_log_force: error -5 returned > > Keeps repeating every 30-secs which indicates that there is some buf/io > error status that is being carried forward. > > >>> Any chance you can reliably reproduce it? > > Yes I have a way to reproduce it, but its not reliable. What I do is setup > a dm-linear over a disk. Create XFS, mount & trigger few copy threads to > copy varying sized files into the FS. At this point pull out the drive > (with scsi-remove-single-device in /proc/scsi/scsi) & in a short-while > convert the dm-linear to dm-ioerror. Then I bring back the underlying > drive, convert back dm-ioerror to dm-linear & try to unmount XFS. > > This problem somehow happens on a newly created XFS. If I copy several > files into XFS/delete them & then copy them again, repeat the drive > failure/recovery experiment it doesn't reproduce. > > Thanks. > > --Shyam > > Subject: Re: XFS hung task in xfs_ail_push_all_sync() when unmounting FS > after disk failure/recovery > From: Carlos Maiolino <cmaiolino@xxxxxxxxxx> > Date: Tue, 22 Mar 2016 16:38:25 +0100 > In-reply-to: <20160322140345.GA54245@bfoster.bfoster> > Mail-followup-to: xfs@xxxxxxxxxxx > User-agent: Mutt/1.5.24 (2015-08-30) > > Hi Brian, > > These traces, and the stack trace presented, looks quite similar with the > one we were discussing a few days ago, using a dm-thin snapshot. > > Looks like with the same bug I've been hunting and Shyam confirmed my > hypothesis > of this bug be able to be reproduced with a regular device. > > If it's the same bug, yes, I reproduced it using upstream kernel. > > The difference between both (this bug and the one I've been working on) is > how > xfs actually behaves when async metadata writes fail. Other than that, it > pretty > much looks the same. > > Trying to unmount the filesystem hungs in xfs_log_force(), well, basically > the > reason I submitted the patch to include the caller into xfs_log_force > trace. I'd > like to see ftrace traces from this system with that patch if possible. > > I didn't have time to keep working on this for the past few days, but > looks like > it's time to come back to it. > > Shyam, after you reconnected the disks, the messages about failed async > metadata > writes stops to be logged? > > Any chance you can reliably reproduce it? > > I'm not a xfs journal expert, but it looks like the writeback of items in > AIL > got stuck due the IO errors, and were never completed, but I don't know > what I > should expect after the disk is reconnected. > > In my case though, with upstream kernel, I didn't get a XFS_SHUTDOWN until > I > tried to unmount the filesystem, which differs from this case, where xfs > looks > to have shutdown the filesystem after a few tries to writeback the > metadata. > > Anyway, I can dig more into it this week, if nobody knows what is going on > before I do it :) > > -----Original Message----- > From: Shyam Kaushik [mailto:shyam@xxxxxxxxxxxxxxxxx] > Sent: 22 March 2016 18:32 > To: 'Brian Foster' > Cc: 'xfs@xxxxxxxxxxx'; Alex Lyakas > Subject: RE: XFS hung task in xfs_ail_push_all_sync() when unmounting FS > after disk failure/recovery > > Hi Brian, > > Thanks for your quick reply. I repeated the test & trace-pipe is > constantly filled with this: > > xfsaild/dm-10-3335 [003] ...2 24890.546491: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.546492: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.546493: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.596491: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.596492: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.596494: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.646497: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.646498: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.646500: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.696467: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.696468: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.696468: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.746548: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.746550: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.746550: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.796479: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.796480: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.796480: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 24890.846467: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 24890.846468: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > > > while regular activity seems to happen on other inodes/kworker threads > > kworker/u8:4-27691 [001] ...1 24895.811474: xfs_writepage: dev 253:10 > ino 0x1801061 pgoff 0x29000 size 0x1aebbc offset 0 length 0 delalloc 1 > unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811477: xfs_invalidatepage: dev > 253:10 ino 0x1801061 pgoff 0x29000 size 0x1aebbc offset 0 length 1000 > delalloc 1 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811478: xfs_releasepage: dev > 253:10 ino 0x1801061 pgoff 0x29000 size 0x1aebbc offset 0 length 0 > delalloc 0 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811482: xfs_writepage: dev 253:10 > ino 0x4017bdf pgoff 0x29000 size 0x1aebbc offset 0 length 0 delalloc 1 > unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811482: xfs_invalidatepage: dev > 253:10 ino 0x4017bdf pgoff 0x29000 size 0x1aebbc offset 0 length 1000 > delalloc 1 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811483: xfs_releasepage: dev > 253:10 ino 0x4017bdf pgoff 0x29000 size 0x1aebbc offset 0 length 0 > delalloc 0 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811485: xfs_writepage: dev 253:10 > ino 0x68048c3 pgoff 0x29000 size 0x1aebbc offset 0 length 0 delalloc 1 > unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811486: xfs_invalidatepage: dev > 253:10 ino 0x68048c3 pgoff 0x29000 size 0x1aebbc offset 0 length 1000 > delalloc 1 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.811486: xfs_releasepage: dev > 253:10 ino 0x68048c3 pgoff 0x29000 size 0x1aebbc offset 0 length 0 > delalloc 0 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.812381: xfs_writepage: dev 253:10 > ino 0x1805e37 pgoff 0x29000 size 0x68470 offset 0 length 0 delalloc 1 > unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.812382: xfs_invalidatepage: dev > 253:10 ino 0x1805e37 pgoff 0x29000 size 0x68470 offset 0 length 1000 > delalloc 1 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.812382: xfs_releasepage: dev > 253:10 ino 0x1805e37 pgoff 0x29000 size 0x68470 offset 0 length 0 delalloc > 0 unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.812385: xfs_writepage: dev 253:10 > ino 0x4019c95 pgoff 0x29000 size 0x68470 offset 0 length 0 delalloc 1 > unwritten 0 > kworker/u8:4-27691 [001] ...1 24895.812385: xfs_invalidatepage: dev > 253:10 ino 0x4019c95 pgoff 0x29000 size 0x68470 offset 0 length 1000 > delalloc 1 unwritten 0 > > > looks like xfsaild is not able to take lock until hung-task timeout kicks > in > > xfsaild/dm-10-3335 [003] ...2 25247.649468: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.649469: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.649469: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 25247.699478: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.699516: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.699517: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > xfsaild/dm-10-3335 [003] ...2 25247.749471: xfs_ilock_nowait: dev > 253:10 ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.749478: xfs_iunlock: dev 253:10 > ino 0xc0 flags ILOCK_SHARED caller xfs_inode_item_push [xfs] > xfsaild/dm-10-3335 [003] ...2 25247.749479: xfs_ail_flushing: dev > 253:10 lip 0xffff8800a9f437b8 lsn 1/38624 type XFS_LI_INODE flags IN_AIL > > Please let me know how to debug this further. Thanks. > > --Shyam > -----Original Message----- > From: Brian Foster [mailto:bfoster@xxxxxxxxxx] > Sent: 22 March 2016 17:49 > To: Shyam Kaushik > Cc: xfs@xxxxxxxxxxx; Alex Lyakas > Subject: Re: XFS hung task in xfs_ail_push_all_sync() when unmounting FS > after disk failure/recovery > > On Tue, Mar 22, 2016 at 04:51:39PM +0530, Shyam Kaushik wrote: > > Hi XFS developers, > > > > We are seeing the following issue with XFS on kernel 3.18.19. > > > > We have XFS mounted over a raw disk. Disk was pulled out manually. There > > were async writes on files that were errored like this > > > ... > > > > And XFS hit metadata & Log IO errors that it decides to shutdown: > > > > Mar 16 16:03:22 host0 kernel: [ 4637.351841] XFS (dm-29): metadata I/O > > error: block 0x3a27fbd0 ("xlog_iodone") error 5 numblks 64 > > Mar 16 16:03:22 host0 kernel: [ 4637.352820] XFS(dm-29): SHUTDOWN!!! > > old_flags=0x0 new_flags=0x2 > > Mar 16 16:03:22 host0 kernel: [ 4637.353187] XFS (dm-29): Log I/O Error > > Detected. Shutting down filesystem > ... > > Later the drive was re-inserted back. After the drive was re-inserted, > XFS > > was attempted to be unmounted > > > > Mar 16 16:16:53 host0 controld: [2557] [ ] umount[202] > > : umount(/sdisk/vol5b0, xfs) > > > > But nothing happens except for the 30-secs xfs_log_force errors that > keeps > > repeating > > > ... > > > > This problem doesn't happen consistently, but happens periodically with > a > > drive failure/recovery followed by XFS unmount. I couldn't find this > issue > > fixed in later kernels. Can you please suggest how I can debug this > issue > > further? > > > > Similar problems have been reproduced due to racy/incorrect EFI/EFD > object tracking, which are internal data structures associated with > freeing extents. > > What happens if you enable tracepoints while the fs is in this hung > unmount state? > > # trace-cmd start -e "xfs:*" > # cat /sys/kernel/debug/tracing/trace_pipe > > Brian > > > Thanks! > > > > --Shyam > > > > _______________________________________________ > > xfs mailing list > > xfs@xxxxxxxxxxx > > http://oss.sgi.com/mailman/listinfo/xfs > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
