Re: [Regression/XFS/PM] Freeze tasks failed in xfsaild

From: Dave Chinner <david@fromorbit.com>
To: Yu Chen <yu.c.chen@intel.com>
Cc: Michal Hocko <mhocko@suse.com>,
	Hendrik Woltersdorf <hendrikw@arcor.de>,
	Dave Chinner <dchinner@redhat.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Jiri Kosina <jkosina@suse.cz>, Len Brown <len.brown@intel.com>,
	Rui Zhang <rui.zhang@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Yu Chen <yu.chen.surf@gmail.com>,
	linux-xfs@vger.kernel.org, linux-pm@vger.kernel.org,
	inux-kernel@vger.kernel.org
Subject: Re: [Regression/XFS/PM] Freeze tasks failed in xfsaild
Date: Tue, 14 Nov 2017 09:52:16 +1100	[thread overview]
Message-ID: <20171113225216.GJ5858@dastard> (raw)
In-Reply-To: <20171113103139.GA18936@yu-chen.sh.intel.com>

On Mon, Nov 13, 2017 at 06:31:39PM +0800, Yu Chen wrote:
> Hi all,
> Currently we are running hibernation stress test on a server
> and unfortunately after 48 rounds of cycling, it fails at a
> early stage that, the xfs task refuses to be frozen by the system:
> 
> [ 1934.221653] PM: Syncing filesystems ...
> [ 1934.661517] PM: done.
> [ 1934.664067] Freezing user space processes ... (elapsed 0.003 seconds) done.
> [ 1934.675251] OOM killer disabled.
> [ 1934.724317] PM: Preallocating image memory... done (allocated 6906555 pages)
> [ 1954.666378] PM: Allocated 27626220 kbytes in 19.93 seconds (1386.16 MB/s)
> [ 1954.673939] Freezing remaining freezable tasks ...
> [ 1974.681089] Freezing of tasks failed after 20.001 seconds (1 tasks refusing to freeze, wq_busy=0):
> [ 1974.691169] xfsaild/dm-1    D    0  1362      2 0x00000080
> [ 1974.697283] Call Trace:
> [ 1974.700014]  __schedule+0x3be/0x830
> [ 1974.703898]  schedule+0x36/0x80
> [ 1974.707440]  _xfs_log_force+0x143/0x280 [xfs]
> [ 1974.712295]  ? schedule_timeout+0x16b/0x350
> [ 1974.716953]  ? wake_up_q+0x80/0x80
> [ 1974.720752]  ? xfsaild+0x16f/0x770 [xfs]
> [ 1974.725134]  xfs_log_force+0x2c/0x80 [xfs]
> [ 1974.729707]  xfsaild+0x16f/0x770 [xfs]
> [ 1974.733885]  kthread+0x109/0x140
> [ 1974.737480]  ? kthread+0x109/0x140
> [ 1974.741271]  ? xfs_trans_ail_cursor_first+0x90/0x90 [xfs]
> [ 1974.747284]  ? kthread_park+0x60/0x60
> [ 1974.751354]  ret_from_fork+0x25/0x30
> [ 1974.755366] Restarting kernel threads ... done.
> [ 1978.259907] OOM killer enabled.
> [ 1978.263405] Restarting tasks ... done.
> 
> The reason for this failure might be that,
> while the kernel thread xfsaild/dm-1 is waiting for
> xfs-buf/dm-1 to wake it up, however the latter
> has already been frozen, thus xfsaild/dm-1 never
> has a chance to be woken up and get froze. (Although
> the xfsaild/dm-1 remains in TASK_UNINTERRUPTIBLE, which
> is quite similar to 'frozen'.)

Should be fixed by this commit in the for-next branch:

0bd89676c4fe xfs: check kthread_should_stop() after the setting of task state

That should get merged into 4.15 with the next merge...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com