RE: XFS hung task in xfs_ail_push_all_sync() when unmounting FS after disk failure/recovery

[Shyam Kaushik <shyam@zadarastorage.com>]

Specific problematic flow in xfs_buf_iodone_callbacks() is this

        if (XFS_BUF_ISASYNC(bp)) {
                xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */

                if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
                        bp->b_flags |= XBF_WRITE | XBF_ASYNC |
                                       XBF_DONE | XBF_WRITE_FAIL;
                        xfs_buf_submit(bp);
                } else {
                        xfs_buf_relse(bp);
                }

That in the else part we just do xfs_buf_relse(). I am not sure if this is
alright. Pls let me know. Thanks.

--Shyam

-----Original Message-----
From: Shyam Kaushik [mailto:shyam@zadarastorage.com]
Sent: 08 April 2016 23:19
To: 'Brian Foster'
Cc: 'david@fromorbit.com'; 'xfs@oss.sgi.com'; Alex Lyakas
Subject: RE: XFS hung task in xfs_ail_push_all_sync() when unmounting FS
after disk failure/recovery

Hi Dave, Brian, Carlos,

I think I see the problem. The problem is when the device just starts to
return IO errors & not shutdown yet that buf could get returned with IO
error. We mark it with XBF_WRITE_FAIL & re-submit the IO. But this IO
could fail again & at this point since we already have XBF_WRITE_FAIL we
dont submit the buf, but leave it in a bad state.

w.r.t. trace-buffer

we have xfs_buf_iodone_callbacks() called with bp->b_error & its an async
IO. So we mark XBF_WRITE_FAIL on the buf & do xfs_buf_submit()

    kworker/2:1H-163   [002] ...1  7513.493658: xfs_buf_item_iodone_async:
dev 253:11 bno 0x2571850 nblks 0x10 hold 2 pincount 0 lock 0 flags
ASYNC|DONE|PAGES caller xfs_buf_ioend [xfs]

but then this again fails & comes back to the same call, but this time
with XBF_WRITE_FAIL set & in this case unfortunately we just do
xfs_buf_relse() & there is no callback flow that is going through.

    kworker/2:1H-163   [002] ...1  7513.494385: xfs_buf_item_iodone_async:
dev 253:11 bno 0x2571850 nblks 0x10 hold 2 pincount 0 lock 0 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_ioend [xfs]

Do you think this is the problem?

There are several bufs that got hit like this. Here is complete trace for
one such buf

   xfsaild/dm-11-22098 [002] ...2  7484.466616: xfs_buf_trylock: dev
253:11 bno 0x25718d0 nblks 0x10 hold 1 pincount 0 lock 0 flags DONE|PAGES
caller xfs_buf_item_push
 [xfs]
   xfsaild/dm-11-22098 [002] ...2  7484.466616: xfs_buf_item_push: dev
253:11 bno 0x25718d0 len 0x2000 hold 1 pincount 0 lock 0 flags DONE|PAGES
recur 0 refcount 0 bli
flags DIRTY|INODE_ALLOC lidesc 0x          (null) liflags IN_AIL
   xfsaild/dm-11-22098 [002] ...2  7484.466616: xfs_buf_delwri_queue: dev
253:11 bno 0x25718d0 nblks 0x10 hold 1 pincount 0 lock 0 flags DONE|PAGES
caller xfs_buf_item
_push [xfs]
   xfsaild/dm-11-22098 [002] ...2  7484.466617: xfs_buf_unlock: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 1 flags
DONE|PAGES|DELWRI_Q caller xfs_buf_i
tem_push [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466765: xfs_buf_trylock: dev
253:11 bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 0 flags
DONE|PAGES|DELWRI_Q caller _xfs_buf
_find [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466765: xfs_buf_find: dev 253:11
bno 0x25718d0 len 0x2000 hold 3 pincount 0 lock 0 flags
READ|TRYLOCK|UNMAPPED caller xfs_buf_g
et_map [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466766: xfs_buf_get: dev 253:11
bno 0x25718d0 len 0x2000 hold 3 pincount 0 lock 0 flags
READ|TRYLOCK|UNMAPPED caller xfs_buf_re
ad_map [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466766: xfs_buf_read: dev 253:11
bno 0x25718d0 len 0x2000 hold 3 pincount 0 lock 0 flags
READ|TRYLOCK|UNMAPPED caller xfs_trans
_read_buf_map [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466792: xfs_buf_delwri_queued: dev
253:11 bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 0 flags
DONE|PAGES|DELWRI_Q caller xf
s_inode_item_push [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466792: xfs_buf_unlock: dev 253:11
bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 1 flags
DONE|PAGES|DELWRI_Q caller xfs_inode
_item_push [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.466792: xfs_buf_rele: dev 253:11
bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 1 flags
DONE|PAGES|DELWRI_Q caller xfs_inode_i
tem_push [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.467962: xfs_buf_trylock: dev
253:11 bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
DONE|PAGES|DELWRI_Q caller __xfs_bu
f_delwri_submit [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.467962: xfs_buf_delwri_split: dev
253:11 bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
DONE|PAGES|DELWRI_Q caller xfs
_buf_delwri_submit_nowait [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.469864: xfs_buf_submit: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|PAGES caller __xfs_buf_delwri_submit [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.469864: xfs_buf_hold: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|PAGES caller xfs_buf_submit [xfs]
   xfsaild/dm-11-22098 [002] ...1  7484.469868: xfs_buf_rele: dev 253:11
bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|PAGES caller xfs_buf_submit [xfs]
    kworker/2:1H-163   [002] ...1  7513.493754: xfs_buf_iodone: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|PAGES caller xfs_buf_ioend_work [xfs]
    kworker/2:1H-163   [002] ...1  7513.493754: xfs_buf_ioerror: dev
253:11 bno 0x25718d0 len 0x2000 hold 2 pincount 0 lock 0 error -5 flags
ASYNC|DONE|PAGES caller xfs_buf_ioend_work [xfs]
    kworker/2:1H-163   [002] ...1  7513.493754: xfs_buf_item_iodone_async:
dev 253:11 bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
ASYNC|DONE|PAGES caller xfs_buf_ioend [xfs]
    kworker/2:1H-163   [002] ...1  7513.493754: xfs_buf_ioerror: dev
253:11 bno 0x25718d0 len 0x2000 hold 2 pincount 0 lock 0 error 0 flags
ASYNC|DONE|PAGES caller xfs_buf_iodone_callbacks [xfs]
    kworker/2:1H-163   [002] ...1  7513.493755: xfs_buf_submit: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_iodone_callbacks [xfs]
    kworker/2:1H-163   [002] ...1  7513.493755: xfs_buf_hold: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_submit [xfs]
    kworker/2:1H-163   [002] ...1  7513.493766: xfs_buf_rele: dev 253:11
bno 0x25718d0 nblks 0x10 hold 3 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_submit [xfs]
    kworker/2:1H-163   [002] ...1  7513.494398: xfs_buf_iodone: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
WRITE|ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_ioend_work [xfs]
    kworker/2:1H-163   [002] ...1  7513.494398: xfs_buf_ioerror: dev
253:11 bno 0x25718d0 len 0x2000 hold 2 pincount 0 lock 0 error -5 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_ioend_work [xfs]
    kworker/2:1H-163   [002] ...1  7513.494398: xfs_buf_item_iodone_async:
dev 253:11 bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 0 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_ioend [xfs]
    kworker/2:1H-163   [002] ...1  7513.494398: xfs_buf_ioerror: dev
253:11 bno 0x25718d0 len 0x2000 hold 2 pincount 0 lock 0 error 0 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_iodone_callbacks [xfs]
    kworker/2:1H-163   [002] ...1  7513.494399: xfs_buf_unlock: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 1 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_iodone_callbacks [xfs]
    kworker/2:1H-163   [002] ...1  7513.494399: xfs_buf_rele: dev 253:11
bno 0x25718d0 nblks 0x10 hold 2 pincount 0 lock 1 flags
ASYNC|DONE|WRITE_FAIL|PAGES caller xfs_buf_iodone_callbacks [xfs]


as seen above the first time buf hits ioerror we retry, but the 2nd time
we give it up without finishing the buf. Its in a stuck state & this keeps
xfsaild thread busy when unmounting trying to flush it out.

Thanks.

--Shyam
-----Original Message-----
From: Shyam Kaushik [mailto:shyam@zadarastorage.com]
Sent: 08 April 2016 19:05
To: 'Brian Foster'
Cc: 'david@fromorbit.com'; 'xfs@oss.sgi.com'; Alex Lyakas
Subject: RE: XFS hung task in xfs_ail_push_all_sync() when unmounting FS
after disk failure/recovery

Hi Brian,

Yes the below report is a bit different than the original report. I wanted
to confirm if the new patches from Dave will see these odd
crashes/hung-task.

I applied Dave's patch & managed to recreate the original issue. With
systemtap I do see that FS has been marked for shutdown (xfs_aildpush() -
mp:0xffff880062d09800 m_flags:4325656), but still the infinite tries keep
happening with xfsaild_push() seeing XFS_IFLOCK on the inode. Pls note
that this issue happens only when I see

XFS (dm-10): Detected failing async write on buffer block 0x368d76a0.
Retrying async write.

in the logs. In all other cases, this problem doesn't happen. So there is
something with this async-write retries that is leaving the state of the
inode with IFLOCK that rest of aildpush is not able to handle.

--Shyam

-----Original Message-----
From: Brian Foster [mailto:bfoster@redhat.com]
Sent: 08 April 2016 18:47
To: Shyam Kaushik
Cc: david@fromorbit.com; xfs@oss.sgi.com; Alex Lyakas
Subject: Re: XFS hung task in xfs_ail_push_all_sync() when unmounting FS
after disk failure/recovery

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@zadarastorage.com]
> Sent: 23 March 2016 15:23
> To: 'Brian Foster'
> Cc: 'xfs@oss.sgi.com'; 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@zadarastorage.com]
> Sent: 22 March 2016 18:32
> To: 'Brian Foster'
> Cc: 'xfs@oss.sgi.com'; 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@redhat.com]
> Sent: 22 March 2016 17:49
> To: Shyam Kaushik
> Cc: xfs@oss.sgi.com; 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@oss.sgi.com
> > http://oss.sgi.com/mailman/listinfo/xfs
>
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
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