Re: linux-next: slab shrinkers: BUG at mm/list_lru.c:92

[Michal Hocko <mhocko@suse.cz>]

On Wed 10-07-13 12:31:39, Dave Chinner wrote:
> On Mon, Jul 08, 2013 at 02:53:52PM +0200, Michal Hocko wrote:
[...]
> > Hmm, it seems I was too optimistic or we have yet another issue here (I
> > guess the later is more probable).
> > 
> > The weekend testing got stuck as well. 
> ....
> > 20761 [<ffffffffa0305fdd>] xlog_grant_head_wait+0xdd/0x1a0 [xfs]
> > [<ffffffffa0306166>] xlog_grant_head_check+0xc6/0xe0 [xfs]
> > [<ffffffffa030627f>] xfs_log_reserve+0xff/0x240 [xfs]
> > [<ffffffffa0302ac4>] xfs_trans_reserve+0x234/0x240 [xfs]
> > [<ffffffffa02c5999>] xfs_create+0x1a9/0x5c0 [xfs]
> > [<ffffffffa02bccca>] xfs_vn_mknod+0x8a/0x1a0 [xfs]
> > [<ffffffffa02bce0e>] xfs_vn_create+0xe/0x10 [xfs]
> > [<ffffffff811763dd>] vfs_create+0xad/0xd0
> > [<ffffffff81177e68>] lookup_open+0x1b8/0x1d0
> > [<ffffffff8117815e>] do_last+0x2de/0x780
> > [<ffffffff8117ae9a>] path_openat+0xda/0x400
> > [<ffffffff8117b303>] do_filp_open+0x43/0xa0
> > [<ffffffff81168ee0>] do_sys_open+0x160/0x1e0
> > [<ffffffff81168f9c>] sys_open+0x1c/0x20
> > [<ffffffff815830e9>] system_call_fastpath+0x16/0x1b
> > [<ffffffffffffffff>] 0xffffffffffffffff
> 
> That's an XFS log space issue, indicating that it has run out of
> space in IO the log and it is waiting for more to come free. That
> requires IO completion to occur.
> 
> > [276962.652076] INFO: task xfs-data/sda9:930 blocked for more than 480 seconds.
> > [276962.652087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > [276962.652093] xfs-data/sda9   D ffff88001ffb9cc8     0   930      2 0x00000000
> 
> Oh, that's why. This is the IO completion worker...
> 
> > [276962.652102]  ffff88003794d198 0000000000000046 ffff8800325f4480 0000000000000000
> > [276962.652113]  ffff88003794c010 0000000000012dc0 0000000000012dc0 0000000000012dc0
> > [276962.652121]  0000000000012dc0 ffff88003794dfd8 ffff88003794dfd8 0000000000012dc0
> > [276962.652128] Call Trace:
> > [276962.652151]  [<ffffffff812a2c22>] ? __blk_run_queue+0x32/0x40
> > [276962.652160]  [<ffffffff812a31f8>] ? queue_unplugged+0x78/0xb0
> > [276962.652171]  [<ffffffff815793a4>] schedule+0x24/0x70
> > [276962.652178]  [<ffffffff8157948c>] io_schedule+0x9c/0xf0
> > [276962.652187]  [<ffffffff811011a9>] sleep_on_page+0x9/0x10
> > [276962.652194]  [<ffffffff815778ca>] __wait_on_bit+0x5a/0x90
> > [276962.652200]  [<ffffffff811011a0>] ? __lock_page+0x70/0x70
> > [276962.652206]  [<ffffffff8110150f>] wait_on_page_bit+0x6f/0x80
> > [276962.652215]  [<ffffffff81067190>] ? autoremove_wake_function+0x40/0x40
> > [276962.652224]  [<ffffffff81112ee1>] ? page_evictable+0x11/0x50
> > [276962.652231]  [<ffffffff81114e43>] shrink_page_list+0x503/0x790
> > [276962.652239]  [<ffffffff8111570b>] shrink_inactive_list+0x1bb/0x570
> > [276962.652246]  [<ffffffff81115d5f>] ? shrink_active_list+0x29f/0x340
> > [276962.652254]  [<ffffffff81115ef9>] shrink_lruvec+0xf9/0x330
> > [276962.652262]  [<ffffffff8111660a>] mem_cgroup_shrink_node_zone+0xda/0x140
> > [276962.652274]  [<ffffffff81160c28>] ? mem_cgroup_reclaimable+0x108/0x150
> > [276962.652282]  [<ffffffff81163382>] mem_cgroup_soft_reclaim+0xb2/0x140
> > [276962.652291]  [<ffffffff811634af>] mem_cgroup_soft_limit_reclaim+0x9f/0x270
> > [276962.652298]  [<ffffffff81116418>] shrink_zones+0x108/0x220
> > [276962.652305]  [<ffffffff8111776a>] do_try_to_free_pages+0x8a/0x360
> > [276962.652313]  [<ffffffff81117d90>] try_to_free_pages+0x130/0x180
> > [276962.652323]  [<ffffffff8110a2fe>] __alloc_pages_slowpath+0x39e/0x790
> > [276962.652332]  [<ffffffff8110a8ea>] __alloc_pages_nodemask+0x1fa/0x210
> > [276962.652343]  [<ffffffff81151c72>] kmem_getpages+0x62/0x1d0
> > [276962.652351]  [<ffffffff81153869>] fallback_alloc+0x189/0x250
> > [276962.652359]  [<ffffffff8115360d>] ____cache_alloc_node+0x8d/0x160
> > [276962.652367]  [<ffffffff81153e51>] __kmalloc+0x281/0x290
> > [276962.652490]  [<ffffffffa02c6e97>] ? kmem_alloc+0x77/0xe0 [xfs]
> > [276962.652540]  [<ffffffffa02c6e97>] kmem_alloc+0x77/0xe0 [xfs]
> > [276962.652588]  [<ffffffffa02c6e97>] ? kmem_alloc+0x77/0xe0 [xfs]
> > [276962.652653]  [<ffffffffa030a334>] xfs_inode_item_format_extents+0x54/0x100 [xfs]
> > [276962.652714]  [<ffffffffa030a63a>] xfs_inode_item_format+0x25a/0x4f0 [xfs]
> > [276962.652774]  [<ffffffffa03081a0>] xlog_cil_prepare_log_vecs+0xa0/0x170 [xfs]
> > [276962.652834]  [<ffffffffa03082a8>] xfs_log_commit_cil+0x38/0x1c0 [xfs]
> > [276962.652894]  [<ffffffffa0303304>] xfs_trans_commit+0x74/0x260 [xfs]
> > [276962.652935]  [<ffffffffa02ac70b>] xfs_setfilesize+0x12b/0x130 [xfs]
> > [276962.652947]  [<ffffffff81076bd0>] ? __migrate_task+0x150/0x150
> > [276962.652988]  [<ffffffffa02ac985>] xfs_end_io+0x75/0xc0 [xfs]
> > [276962.652997]  [<ffffffff8105e934>] process_one_work+0x1b4/0x380
> 
> ... is running IO completion work and trying to commit a transaction
> that is blocked in memory allocation which is waiting for IO
> completion. It's disappeared up it's own fundamental orifice.
> 
> Ok, this has absolutely nothing to do with the LRU changes - this is
> a pre-existing XFS/mm interaction problem from around 3.2. 

OK. I am retesting with ext3 now.

-- 
Michal Hocko
SUSE Labs

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