xfs+md(raid5) xfssyncd & kswapd & pdflush hung in d-state

From: David Flynn
Date: Wed Mar 19 2008 - 19:17:30 EST

We are currently experiencing a problem with writing to xfs on a 20disk
raid5 array. It seems very similar to a post in 2007nov09:

Re: 2.6.23.1: mdadm/raid5 hung/d-state

Using kernel 2.6.24. Unlike the previous post the array was in a clean
state so no resync was occuring. We are able to read from the array,
but any process that writes joins the list of blocked tasks

The machine is:
2 of dual core opteron 280
16GiB RAM
4 lots of 5 sata disks connected to sil3124 sata hba.
Running 2.6.24

There was a single rsync process accessing the array at the time
(~40MB/sec).

Random other bits[1]:
# cat /sys/block/md1/md/stripe_cache_active
256
# cat /sys/block/md1/md/stripe_cache_size
256

Example of sysrq-w:

pdflush D ffffffff804297c0 0 245 2
ffff810274dd1920 0000000000000046 0000000000000000 ffffffff80305ba3
ffff810476524680 ffff81047748e000 ffff810276456800 ffff81047748e250
00000000ffffffff ffff8102758a0d30 0000000000000000 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff80293fc7>] new_slab+0x1e5/0x20c
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff802941b6>] __slab_alloc+0x1c8/0x3a9
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802babc1>] __bio_add_page+0x109/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f46>] :xfs:xfs_submit_ioend+0x88/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff802771e3>] __writepage+0xa/0x23
[<ffffffff8027767c>] write_cache_pages+0x176/0x2a5
[<ffffffff802771d9>] __writepage+0x0/0x23
[<ffffffff802777e7>] do_writepages+0x20/0x2d
[<ffffffff802b3ce1>] __writeback_single_inode+0x18d/0x2e0
[<ffffffff8026fb13>] delayacct_end+0x7d/0x88
[<ffffffff802b4175>] sync_sb_inodes+0x1b6/0x273
[<ffffffff802b4595>] writeback_inodes+0x69/0xbb
[<ffffffff8027801a>] wb_kupdate+0x9e/0x10d
[<ffffffff8027839e>] pdflush+0x0/0x204
[<ffffffff802784f8>] pdflush+0x15a/0x204
[<ffffffff80277f7c>] wb_kupdate+0x0/0x10d
[<ffffffff80247ecb>] kthread+0x47/0x74
[<ffffffff8020cc48>] child_rip+0xa/0x12
[<ffffffff80247e84>] kthread+0x0/0x74
[<ffffffff8020cc3e>] child_rip+0x0/0x12

I've attatched the rest of the output.
Other than the blocked processes, the machine is idle.

After rebooting the machine, we increased stripe_cache_size to 512 and
are currently seeing the same processes (now with md1_resync) periodically
hang in the Dstate, best described as the almost the entire machine
freezing for upto a minute then recovering.

I say almost as some processes seem unaffected, eg my existing ssh login
to echo w > /proc/sysrq-trigger and a vmware virtual
machine (root filesystem for host and guest is an nfsroot mounted from
elsewhere). Trying to login during these periods of tenseness fails
though.

During these tense periods everything is idle with anything touching md1
in the D state.

Any thoughts?

..david
SysRq : Show Blocked State
task PC stack pid father
pdflush D ffff81047748e000 0 245 2
ffff810274dd1920 0000000000000046 ffff810274618680 ffffffff80305ba3
ffff810274618680 ffff81047748e000 ffff810477474000 ffff81047748e250
ffff810476159400 ffff8102758a0d30 0000000000000246 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff80293fc7>] new_slab+0x1e5/0x20c
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff802941b6>] __slab_alloc+0x1c8/0x3a9
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802babc1>] __bio_add_page+0x109/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f46>] :xfs:xfs_submit_ioend+0x88/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff802771e3>] __writepage+0xa/0x23
[<ffffffff8027767c>] write_cache_pages+0x176/0x2a5
[<ffffffff802771d9>] __writepage+0x0/0x23
[<ffffffff802777e7>] do_writepages+0x20/0x2d
[<ffffffff802b3ce1>] __writeback_single_inode+0x18d/0x2e0
[<ffffffff8026fb13>] delayacct_end+0x7d/0x88
[<ffffffff802b4175>] sync_sb_inodes+0x1b6/0x273
[<ffffffff802b4595>] writeback_inodes+0x69/0xbb
[<ffffffff8027801a>] wb_kupdate+0x9e/0x10d
[<ffffffff8027839e>] pdflush+0x0/0x204
[<ffffffff802784f8>] pdflush+0x15a/0x204
[<ffffffff80277f7c>] wb_kupdate+0x0/0x10d
[<ffffffff80247ecb>] kthread+0x47/0x74
[<ffffffff8020cc48>] child_rip+0xa/0x12
[<ffffffff80247e84>] kthread+0x0/0x74
[<ffffffff8020cc3e>] child_rip+0x0/0x12

kswapd0 D ffffffff804297c0 0 247 2
ffff810274dd7880 0000000000000046 ffff810274618680 ffffffff80305ba3
ffff810274618680 ffff81047748e800 ffff81047748e000 ffff81047748ea50
ffff810476159400 ffff8102758a0d30 0000000000000246 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff80276a69>] __alloc_pages+0x66/0x309
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff80293fc7>] new_slab+0x1e5/0x20c
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff802941b6>] __slab_alloc+0x1c8/0x3a9
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802bac0c>] __bio_add_page+0x154/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f65>] :xfs:xfs_submit_ioend+0xa7/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff8027a93a>] shrink_page_list+0x346/0x570
[<ffffffff8027ac81>] shrink_inactive_list+0x11d/0x381
[<ffffffff8027afca>] shrink_zone+0xe5/0x108
[<ffffffff8027b4c8>] kswapd+0x2fc/0x49b
[<ffffffff80414bf4>] thread_return+0x3d/0xab
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff8027b1cc>] kswapd+0x0/0x49b
[<ffffffff80247ecb>] kthread+0x47/0x74
[<ffffffff8020cc48>] child_rip+0xa/0x12
[<ffffffff80247e84>] kthread+0x0/0x74
[<ffffffff8020cc3e>] child_rip+0x0/0x12

kswapd1 D 0000000000000001 0 248 2
ffff810274dd9880 0000000000000046 ffff810274dd9848 ffffffff80305ba3
ffff810274618680 ffff81047748f000 ffff810475dbb800 ffff81047748f250
00000000ffffffff ffff8102758a0d30 0000000000000400 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff88381a55>] :xfs:xfs_start_page_writeback+0x24/0x38
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802babc1>] __bio_add_page+0x109/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f65>] :xfs:xfs_submit_ioend+0xa7/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff8027a93a>] shrink_page_list+0x346/0x570
[<ffffffff8027ac81>] shrink_inactive_list+0x11d/0x381
[<ffffffff8027afca>] shrink_zone+0xe5/0x108
[<ffffffff8027b4c8>] kswapd+0x2fc/0x49b
[<ffffffff80414bf4>] thread_return+0x3d/0xab
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff8027b1cc>] kswapd+0x0/0x49b
[<ffffffff80247ecb>] kthread+0x47/0x74
[<ffffffff8020cc48>] child_rip+0xa/0x12
[<ffffffff80247e84>] kthread+0x0/0x74
[<ffffffff8020cc3e>] child_rip+0x0/0x12

xfssyncd D ffffffff804297c0 0 4132 2
ffff81047643db60 0000000000000046 0000000000000000 ffffffff80305ba3
ffff810274618680 ffff81047584d000 ffffffff804dc4a0 ffff81047584d250
00000000ffffffff ffff8102758a0d30 0000000000000000 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022e6a5>] __wake_up+0x38/0x4f
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff8836d61e>] :xfs:xlog_write+0x3e0/0x459
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff8029265d>] get_partial_node+0x15/0x7e
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff8022da0e>] find_busiest_group+0x248/0x6ea
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff8838473f>] :xfs:_xfs_buf_ioapply+0x266/0x291
[<ffffffff883847a3>] :xfs:xfs_buf_iorequest+0x39/0x66
[<ffffffff8836be90>] :xfs:xlog_bdstrat_cb+0x16/0x3c
[<ffffffff8836ce5e>] :xfs:xlog_sync+0x238/0x3fb
[<ffffffff8836dac7>] :xfs:xlog_state_sync_all+0xa6/0x1c0
[<ffffffff8023e0ff>] try_to_del_timer_sync+0x51/0x5a
[<ffffffff8836e02a>] :xfs:_xfs_log_force+0x5c/0x6b
[<ffffffff8837ac0d>] :xfs:xfs_syncsub+0x35/0x241
[<ffffffff8838925c>] :xfs:xfs_sync_worker+0x17/0x36
[<ffffffff883894f1>] :xfs:xfssyncd+0x13b/0x18f
[<ffffffff883893b6>] :xfs:xfssyncd+0x0/0x18f
[<ffffffff80247ecb>] kthread+0x47/0x74
[<ffffffff8020cc48>] child_rip+0xa/0x12
[<ffffffff80247e84>] kthread+0x0/0x74
[<ffffffff8020cc3e>] child_rip+0x0/0x12

rsync D ffff81047120a000 0 5096 1
ffff8104715874b8 0000000000000086 ffff810274618680 ffffffff80305ba3
ffff810274618680 ffff81047120a000 ffff81047584d000 ffff81047120a250
ffff810476159400 ffff8102758a0d30 0000000000000246 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022e6a5>] __wake_up+0x38/0x4f
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff80293fc7>] new_slab+0x1e5/0x20c
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff802941b6>] __slab_alloc+0x1c8/0x3a9
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802bac0c>] __bio_add_page+0x154/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f65>] :xfs:xfs_submit_ioend+0xa7/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff8027a93a>] shrink_page_list+0x346/0x570
[<ffffffff8027ac81>] shrink_inactive_list+0x11d/0x381
[<ffffffff8027799a>] get_dirty_limits+0x1d/0x184
[<ffffffff8027afca>] shrink_zone+0xe5/0x108
[<ffffffff8027bd77>] try_to_free_pages+0x17b/0x288
[<ffffffff80276bcd>] __alloc_pages+0x1ca/0x309
[<ffffffff8027185f>] __grab_cache_page+0x33/0x6f
[<ffffffff802b8d6f>] block_write_begin+0x38/0xcd
[<ffffffff88381b35>] :xfs:xfs_vm_write_begin+0x22/0x27
[<ffffffff88382155>] :xfs:xfs_get_blocks+0x0/0xe
[<ffffffff80272484>] generic_file_buffered_write+0x153/0x670
[<ffffffff803a9348>] memcpy_toiovec+0x36/0x66
[<ffffffff88388b78>] :xfs:xfs_write+0x54d/0x789
[<ffffffff80299018>] do_sync_write+0xc9/0x10c
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff80299807>] vfs_write+0xc6/0x16f
[<ffffffff80299dc2>] sys_write+0x45/0x6e
[<ffffffff8020be2e>] system_call+0x7e/0x83

bash D ffffffff804297c0 0 6739 6647
ffff81037f4fd768 0000000000000086 0000000000000000 ffffffff80305ba3
ffff810274618680 ffff8102836ec800 ffff8102764b6800 ffff8102836eca50
00000000ffffffff ffff8102758a0d30 0000000000000000 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff8022e6a5>] __wake_up+0x38/0x4f
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff88381a55>] :xfs:xfs_start_page_writeback+0x24/0x38
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff883826ed>] :xfs:xfs_cluster_write+0xcd/0xf2
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff802bac0c>] __bio_add_page+0x154/0x1ce
[<ffffffff88381ea0>] :xfs:xfs_submit_ioend_bio+0x1e/0x27
[<ffffffff88381f65>] :xfs:xfs_submit_ioend+0xa7/0xc6
[<ffffffff88382d9e>] :xfs:xfs_page_state_convert+0x508/0x557
[<ffffffff802749d0>] get_pageblock_flags_group+0x3e/0x7f
[<ffffffff88382f39>] :xfs:xfs_vm_writepage+0xa7/0xde
[<ffffffff8027a93a>] shrink_page_list+0x346/0x570
[<ffffffff8027ac81>] shrink_inactive_list+0x11d/0x381
[<ffffffff8027799a>] get_dirty_limits+0x1d/0x184
[<ffffffff8027afca>] shrink_zone+0xe5/0x108
[<ffffffff8027bd77>] try_to_free_pages+0x17b/0x288
[<ffffffff80276bcd>] __alloc_pages+0x1ca/0x309
[<ffffffff882fde17>] :raid456:grow_one_stripe+0x70/0xd8
[<ffffffff882fdf08>] :raid456:raid5_store_stripe_cache_size+0x89/0xac
[<ffffffff80276a69>] __alloc_pages+0x66/0x309
[<ffffffff882df6a6>] :md_mod:md_attr_store+0x61/0x88
[<ffffffff802db3d4>] sysfs_write_file+0xd2/0x110
[<ffffffff80299807>] vfs_write+0xc6/0x16f
[<ffffffff80299dc2>] sys_write+0x45/0x6e
[<ffffffff8020be2e>] system_call+0x7e/0x83

vim D ffff810477016800 0 7040 7013
ffff81001b11f748 0000000000000086 ffff810274618680 ffffffff80305ba3
ffff810274618680 ffff810477016800 ffff81047655e800 ffff810477016a50
ffff810476159400 ffff8102758a0d30 0000000000000246 0000000000000000
Call Trace:
[<ffffffff80305ba3>] __generic_unplug_device+0x13/0x24
[<ffffffff882fcfcf>] :raid456:get_active_stripe+0x233/0x4c7
[<ffffffff80247fd9>] wake_up_bit+0x11/0x22
[<ffffffff8022ee03>] default_wake_function+0x0/0xe
[<ffffffff88302e6c>] :raid456:make_request+0x3f0/0x568
[<ffffffff80247fea>] autoremove_wake_function+0x0/0x2e
[<ffffffff802715e0>] find_lock_page+0x1f/0x7f
[<ffffffff803042be>] generic_make_request+0x30e/0x349
[<ffffffff802737a4>] mempool_alloc+0x24/0xda
[<ffffffff803043d4>] submit_bio+0xdb/0xe2
[<ffffffff8838473f>] :xfs:_xfs_buf_ioapply+0x266/0x291
[<ffffffff883847a3>] :xfs:xfs_buf_iorequest+0x39/0x66
[<ffffffff8836be90>] :xfs:xlog_bdstrat_cb+0x16/0x3c
[<ffffffff8836ce5e>] :xfs:xlog_sync+0x238/0x3fb
[<ffffffff8836dac7>] :xfs:xlog_state_sync_all+0xa6/0x1c0
[<ffffffff8836e02a>] :xfs:_xfs_log_force+0x5c/0x6b
[<ffffffff88381546>] :xfs:kmem_zone_alloc+0x52/0x9f
[<ffffffff883633a0>] :xfs:xfs_iget_core+0x19d/0x63a
[<ffffffff802aaf9e>] alloc_inode+0x152/0x1c2
[<ffffffff883638d8>] :xfs:xfs_iget+0x9b/0x13f
[<ffffffff88378906>] :xfs:xfs_trans_iget+0xae/0x124
[<ffffffff88366d36>] :xfs:xfs_ialloc+0xa0/0x536
[<ffffffff883792d7>] :xfs:xfs_dir_ialloc+0x84/0x2d1
[<ffffffff88376ccc>] :xfs:xfs_trans_reserve+0xdd/0x1b0
[<ffffffff802a2618>] __link_path_walk+0xd2d/0xd4e
[<ffffffff8837e2e0>] :xfs:xfs_create+0x275/0x4d2
[<ffffffff88387b51>] :xfs:xfs_vn_mknod+0x148/0x242
[<ffffffff88387262>] :xfs:xfs_vn_permission+0x15/0x19
[<ffffffff802a14a6>] vfs_create+0xcf/0x140
[<ffffffff802a36b1>] open_namei+0x1a0/0x63c
[<ffffffff80297c7e>] do_filp_open+0x1c/0x38
[<ffffffff80297969>] get_unused_fd_flags+0x72/0x120
[<ffffffff80297ce0>] do_sys_open+0x46/0xc3
[<ffffffff8020be2e>] system_call+0x7e/0x83

rm D ffffffff804297c0 0 7043 6820
ffff810465985bd8 0000000000000082 0000000000000000 ffffffff88178043
ffff810465985b68 ffff81047610a000 ffff8102764b6800 ffff81047610a250
00000000ffffffff ffffffff88159e20 0000000000000000 0000000000000000
Call Trace:
[<ffffffff88178043>] :nfs:nfs_do_access+0x2b/0x31b
[<ffffffff80415c22>] __down_read+0x82/0x9a
[<ffffffff8837bb8c>] :xfs:xfs_access+0x18/0x3f
[<ffffffff88387262>] :xfs:xfs_vn_permission+0x15/0x19
[<ffffffff8029fd91>] permission+0xb6/0x10b
[<ffffffff802a1a41>] __link_path_walk+0x156/0xd4e
[<ffffffff88183001>] :nfs:nfs_writepages_callback+0x0/0x21
[<ffffffff802a2691>] link_path_walk+0x58/0xe0
[<ffffffff80282a54>] __vma_link+0x42/0x4b
[<ffffffff802a2a01>] do_path_lookup+0x1a3/0x21b
[<ffffffff802a16ac>] getname+0x14c/0x1b3
[<ffffffff802a324e>] __user_walk_fd+0x37/0x4c
[<ffffffff8029c307>] vfs_lstat_fd+0x18/0x47
[<ffffffff80282a54>] __vma_link+0x42/0x4b
[<ffffffff8029c34f>] sys_newlstat+0x19/0x31
[<ffffffff802a4ad2>] vfs_ioctl+0x243/0x25c
[<ffffffff8031315f>] __up_write+0x21/0x10e
[<ffffffff804162e9>] error_exit+0x0/0x51
[<ffffffff8020be2e>] system_call+0x7e/0x83