Comment 1 for bug 606981

We also experience this bug

Also using O_DIRECT with innodb_flush_log_at_trx_commit=2

With the following command
innobackupex-1.5.1 --slave-info --stream=tar . 2> /tmp/$source.xtrabackup.log| gzip - | nc -vw60 $target $port

Sample output from /var/log/messages

[6896419.396214] ------------[ cut here ]------------
[6896419.396214] WARNING: at fs/xfs/linux-2.6/xfs_lrw.c:726 xfs_write+0x3f5/0x722 [xfs]()
[6896419.396214] Modules linked in: ipv6 xfs loop snd_pcm snd_timer snd soundcore snd_page_alloc i2c_i801 psmouse pcspkr i2c_core serio_raw button joydev evdev ext3 jbd mbcache dm_mirror dm_log dm_snapshot dm_mod raid1 raid0 md_mod sd_mod sg sr_mod cdrom usbhid hid ff_memless mptsas mptscsih mptbase ahci scsi_transport_sas libata scsi_mod dock ehci_hcd uhci_hcd igb thermal processor fan thermal_sys [last unloaded: scsi_wait_scan]
[6896419.396214] Pid: 6909, comm: mysqld Tainted: G W 2.6.26-2-amd64 #1
[6896419.396214]
[6896419.396214] Call Trace:
[6896419.396214] [<ffffffff80234930>] warn_on_slowpath+0x51/0x7a
[6896419.396214] [<ffffffff80231997>] check_preempt_wakeup+0xc4/0xf0
[6896419.396214] [<ffffffff8022c157>] try_to_wake_up+0x118/0x129
[6896419.396214] [<ffffffff8031e230>] __up_write+0x82/0x10e
[6896419.396214] [<ffffffffa022ec68>] :xfs:xfs_iunlock+0x42/0x7c
[6896419.396214] [<ffffffffa02526cc>] :xfs:xfs_write+0x3f5/0x722
[6896419.396214] [<ffffffff802483e0>] enqueue_hrtimer+0xd7/0xe4
[6896419.396223] [<ffffffff8029ae83>] do_sync_write+0xc9/0x10c
[6896419.396231] [<ffffffff80246171>] autoremove_wake_function+0x0/0x2e
[6896419.396236] [<ffffffff8029b62d>] vfs_write+0xad/0x156
[6896419.396236] [<ffffffff8029c2ee>] fget_light+0x4f/0x82
[6896419.396236] [<ffffffff8029bcb8>] sys_pwrite64+0x50/0x70
[6896419.396236] [<ffffffff8020c267>] ptregscall_common+0x67/0xb0
[6896419.396236] [<ffffffff8020beda>] system_call_after_swapgs+0x8a/0x8f
[6896419.396236]