[PATCH 0/2] xfs: write back inodes during reclaim

[Yann Dupont]

Le 07/04/2011 08:19, Dave Chinner a écrit :
> This series fixes an OOM problem where VFS-only dirty inodes
> accumulate on an XFS filesystem due to atime updates causing OOM to
> occur.
>
> The first patch fixes a deadlock triggering bdi-flusher writeback
> from memory reclaim when a new bdi-flusher thread needs to be forked
> and no memory is available.
>
> the second adds a bdi-flusher kick from XFS's inode cache shrinker
> so that when memory is low the VFS starts writing back dirty inodes
> so they can be reclaimed as they get cleaned rather than remaining
> dirty and pinning the inode cache in memory.
>
> _______________________________________________
> xfs mailing list
> xfs at oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs
>
Hello, we've been hit for some times by a bug (oom) which may been 
related to this one. Our server contains lots of samba server (in 
linux-vserver, this is NOT a vanilla kernel) and is also NFS kernel server.
The oom generally happens after 1 month of uptime, and last week we also 
had the problem after 1 week.

for example this one :
Feb 25 12:54:15 strathisla.u11.univ-nantes.prive kernel: 
[2743591.087102] Node 0 Normal free:8840kB min:12968kB low:16208kB 
high:19452kB active_anon:140168kB inactive_anon:21200kB 
active_file:1446724kB inactive_file:10741224kB unevictable:4172kB 
isolated(anon):0kB isolated(file):0kB present:13186560kB mlocked:4172kB 
dirty:42924kB writeback:249420kB mapped:60296kB shmem:7028kB 
slab_reclaimable:758752kB slab_unreclaimable:136528kB 
kernel_stack:6784kB pagetables:8388kB unstable:0kB bounce:0kB 
writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Feb 25 12:57:21 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877303] admind: page allocation failure. order:0, mode:0x4020
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877340] Pid: 10121, comm: admind Not tainted 
2.6.32-5-vserver-amd64 #1
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877369] Call Trace:
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877392] <IRQ>  [<ffffffff810c3f43>] ? 
__alloc_pages_nodemask+0x592/0x5f3
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877449]  [<ffffffff810f0d1e>] ? new_slab+0x5b/0x1ca
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877477]  [<ffffffff810f107d>] ? __slab_alloc+0x1f0/0x39b
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877507]  [<ffffffff812565c8>] ? __netdev_alloc_skb+0x29/0x45
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877537]  [<ffffffff810f1aaf>] ? 
__kmalloc_node_track_caller+0xbb/0x11b
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877568]  [<ffffffff812565c8>] ? __netdev_alloc_skb+0x29/0x45
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877598]  [<ffffffff812555f5>] ? __alloc_skb+0x69/0x15a
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877627]  [<ffffffff812565c8>] ? __netdev_alloc_skb+0x29/0x45
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877673]  [<ffffffffa00af52a>] ? bnx2_alloc_rx_skb+0x4c/0x1a3 [bnx2]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877706]  [<ffffffffa00b34fb>] ? bnx2_poll_work+0x4f3/0xa7e [bnx2]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877738]  [<ffffffffa00b3c47>] ? bnx2_poll+0x11b/0x229 [bnx2]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877768]  [<ffffffff8125c851>] ? net_rx_action+0xae/0x1c9
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877799]  [<ffffffff8105430b>] ? __do_softirq+0xdd/0x1a2
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877828]  [<ffffffff81011cac>] ? call_softirq+0x1c/0x30
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877857]  [<ffffffff8101322b>] ? do_softirq+0x3f/0x7c
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877885]  [<ffffffff8105417a>] ? irq_exit+0x36/0x76
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877912]  [<ffffffff81012922>] ? do_IRQ+0xa0/0xb6
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877939]  [<ffffffff810114d3>] ? ret_from_intr+0x0/0x11
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.877966] <EOI>  [<ffffffffa02304cf>] ? 
xfs_reclaim_inode+0x0/0xe0 [xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878019]  [<ffffffff8130a7c5>] ? _write_lock+0x7/0xf
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878058]  [<ffffffffa0230e3d>] ? xfs_inode_ag_walk+0x4e/0xef [xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878098]  [<ffffffffa02304cf>] ? xfs_reclaim_inode+0x0/0xe0 [xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878138]  [<ffffffffa0230f4f>] ? xfs_inode_ag_iterator+0x71/0xb2 
[xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878179]  [<ffffffffa02304cf>] ? xfs_reclaim_inode+0x0/0xe0 [xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878219]  [<ffffffffa0230feb>] ? 
xfs_reclaim_inode_shrink+0x5b/0x10d [xfs]
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878265]  [<ffffffff810c8dd1>] ? shrink_slab+0xe0/0x153
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878294]  [<ffffffff810c9d2e>] ? try_to_free_pages+0x26a/0x38e
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878323]  [<ffffffff810c6ceb>] ? isolate_pages_global+0x0/0x20f
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878353]  [<ffffffff810c3d7e>] ? __alloc_pages_nodemask+0x3cd/0x5f3
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878383]  [<ffffffff810f0d05>] ? new_slab+0x42/0x1ca
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878411]  [<ffffffff810f107d>] ? __slab_alloc+0x1f0/0x39b
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878441]  [<ffffffff8110437f>] ? getname+0x23/0x1a0
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878468]  [<ffffffff8110437f>] ? getname+0x23/0x1a0
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878495]  [<ffffffff810f1558>] ? kmem_cache_alloc+0x7f/0xf0
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878524]  [<ffffffff8110437f>] ? getname+0x23/0x1a0
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878552]  [<ffffffff810f75b3>] ? do_sys_open+0x1d/0xfc
Feb 25 12:57:22 strathisla.u11.univ-nantes.prive kernel: 
[2743777.878580]  [<ffffffff81037623>] ? ia32_sysret+0x0/0x5


I saw this on 2.6.32 kernels ; Since 2 days we're testing 2.6.38.2 
kernel on the very same machine.

Some questions :

-What kernel versions are known to be impacted ?
-What is the plan for inclusion in kernel ? Is this considered 
appropriate material for 2.6.38.4 and older stable kernels ?
- Is mounting with noatime can alleviate the problem ?

Regards,

-- 
Yann Dupont - Service IRTS, DSI Université de Nantes
Tel : 02.53.48.49.20 - Mail/Jabber : Yann.Dupont at univ-nantes.fr