I'm seeing this on
Linux box05 2.6.32-02063209-generic #02063209 SMP Wed Feb 24 10:09:53 UTC 2010 x86_64 GNU/Linux

occurs while coping a disk to nfs share on another box

Feb 24 21:11:29 box05 kernel: [  600.530615] INFO: task flush-0:25:2623 blocked for more than 120 seconds.
Feb 24 21:11:29 box05 kernel: [  600.530618] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Feb 24 21:11:29 box05 kernel: [  600.530622] flush-0:25    D 0000000000000001     0  2623      2 0x00000000
Feb 24 21:11:29 box05 kernel: [  600.530628]  ffff8800c7bdd110 0000000000000046 0000000000000000 ffff8800c7bddfd8
Feb 24 21:11:29 box05 kernel: [  600.530634]  ffff880129f45b40 0000000000015a80 0000000000015a80 ffff8800c7bddfd8
Feb 24 21:11:29 box05 kernel: [  600.530640]  0000000000015a80 ffff8800c7bddfd8 0000000000015a80 ffff880129f45f00
Feb 24 21:11:29 box05 kernel: [  600.530645] Call Trace:
Feb 24 21:11:29 box05 kernel: [  600.530651]  [<ffffffff81533c52>] io_schedule+0x42/0x60
Feb 24 21:11:29 box05 kernel: [  600.530668]  [<ffffffffa0c31f39>] nfs_wait_bit_uninterruptible+0x9/0x10 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530673]  [<ffffffff815343d5>] __wait_on_bit+0x55/0x80
Feb 24 21:11:29 box05 kernel: [  600.530689]  [<ffffffffa0c31f30>] ? nfs_wait_bit_uninterruptible+0x0/0x10 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530706]  [<ffffffffa0c31f30>] ? nfs_wait_bit_uninterruptible+0x0/0x10 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530711]  [<ffffffff81534478>] out_of_line_wait_on_bit+0x78/0x90
Feb 24 21:11:29 box05 kernel: [  600.530716]  [<ffffffff8107f760>] ? wake_bit_function+0x0/0x30
Feb 24 21:11:29 box05 kernel: [  600.530732]  [<ffffffffa0c31f28>] nfs_wait_on_request+0x28/0x30 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530750]  [<ffffffffa0c36199>] nfs_wait_on_requests_locked+0x79/0xd0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530757]  [<ffffffff8111e01b>] ? get_partial_node+0x9b/0xc0
Feb 24 21:11:29 box05 kernel: [  600.530775]  [<ffffffffa0c37253>] nfs_sync_mapping_wait+0xb3/0x140 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530782]  [<ffffffff81437a58>] ? pskb_expand_head+0x58/0x1a0
Feb 24 21:11:29 box05 kernel: [  600.530800]  [<ffffffffa0c37366>] nfs_wb_page_priority+0x86/0xe0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530806]  [<ffffffff8112744e>] ? page_cgroup_zoneinfo+0x2e/0x40
Feb 24 21:11:29 box05 kernel: [  600.530823]  [<ffffffffa0c373ce>] nfs_wb_page+0xe/0x10 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530836]  [<ffffffffa0c26975>] nfs_release_page+0x35/0x60 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530842]  [<ffffffff810e58eb>] try_to_release_page+0x2b/0x40
Feb 24 21:11:29 box05 kernel: [  600.530847]  [<ffffffff810f27e7>] shrink_page_list+0x4b7/0x550
Feb 24 21:11:29 box05 kernel: [  600.530852]  [<ffffffff810f2abd>] ? isolate_lru_pages+0x23d/0x280
Feb 24 21:11:29 box05 kernel: [  600.530858]  [<ffffffff810f2e43>] shrink_inactive_list+0x2f3/0x700
Feb 24 21:11:29 box05 kernel: [  600.530864]  [<ffffffff81436ba9>] ? __alloc_skb+0x49/0x180
Feb 24 21:11:29 box05 kernel: [  600.530870]  [<ffffffff810e8f23>] ? move_freepages_block+0x73/0x80
Feb 24 21:11:29 box05 kernel: [  600.530875]  [<ffffffff810f32a1>] shrink_list+0x51/0xa0
Feb 24 21:11:29 box05 kernel: [  600.530880]  [<ffffffff810f37fa>] shrink_zone+0x1ea/0x200
Feb 24 21:11:29 box05 kernel: [  600.530885]  [<ffffffff810f4233>] shrink_zones+0x63/0xf0
Feb 24 21:11:29 box05 kernel: [  600.530891]  [<ffffffff810f4330>] do_try_to_free_pages+0x70/0x280
Feb 24 21:11:29 box05 kernel: [  600.530896]  [<ffffffff810f46ac>] try_to_free_pages+0x9c/0xc0
Feb 24 21:11:29 box05 kernel: [  600.530901]  [<ffffffff810f2b00>] ? isolate_pages_global+0x0/0x50
Feb 24 21:11:29 box05 kernel: [  600.530907]  [<ffffffff810ebd1b>] __alloc_pages_slowpath+0x25b/0x540
Feb 24 21:11:29 box05 kernel: [  600.530913]  [<ffffffff810ec146>] __alloc_pages_nodemask+0x146/0x180
Feb 24 21:11:29 box05 kernel: [  600.530919]  [<ffffffff8111a317>] alloc_pages_current+0x87/0xd0
Feb 24 21:11:29 box05 kernel: [  600.530925]  [<ffffffff8111f60c>] allocate_slab+0x11c/0x1b0
Feb 24 21:11:29 box05 kernel: [  600.530931]  [<ffffffff8111f6cb>] new_slab+0x2b/0x190
Feb 24 21:11:29 box05 kernel: [  600.530935]  [<ffffffff811218b1>] __slab_alloc+0x121/0x230
Feb 24 21:11:29 box05 kernel: [  600.530952]  [<ffffffffa0c369a2>] ? nfs_writedata_alloc+0x82/0xb0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530970]  [<ffffffffa0c369a2>] ? nfs_writedata_alloc+0x82/0xb0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.530975]  [<ffffffff81123186>] __kmalloc+0x1a6/0x1f0
Feb 24 21:11:29 box05 kernel: [  600.530992]  [<ffffffffa0c369a2>] nfs_writedata_alloc+0x82/0xb0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531009]  [<ffffffffa0c369ed>] nfs_flush_one+0x1d/0xf0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531026]  [<ffffffffa0c31e38>] nfs_pageio_doio+0x48/0x70 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531042]  [<ffffffffa0c31ea9>] nfs_pageio_complete+0x9/0x10 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531059]  [<ffffffffa0c36724>] nfs_writepages+0xd4/0x120 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531077]  [<ffffffffa0c369d0>] ? nfs_flush_one+0x0/0xf0 [nfs]
Feb 24 21:11:29 box05 kernel: [  600.531082]  [<ffffffff8105c536>] ? update_curr+0xb6/0x150
Feb 24 21:11:29 box05 kernel: [  600.531088]  [<ffffffff810ee37c>] do_writepages+0x1c/0x30
Feb 24 21:11:29 box05 kernel: [  600.531095]  [<ffffffff8114d5e7>] writeback_single_inode+0xb7/0x270
Feb 24 21:11:29 box05 kernel: [  600.531100]  [<ffffffff81083989>] ? down_read_trylock+0x9/0x10
Feb 24 21:11:29 box05 kernel: [  600.531106]  [<ffffffff8114dde2>] writeback_inodes_wb+0x162/0x210
Feb 24 21:11:29 box05 kernel: [  600.531112]  [<ffffffff810374c9>] ? default_spin_lock_flags+0x9/0x10
Feb 24 21:11:29 box05 kernel: [  600.531118]  [<ffffffff8114dfb6>] wb_writeback+0x126/0x1e0
Feb 24 21:11:29 box05 kernel: [  600.531124]  [<ffffffff8114e16e>] ? wb_work_complete+0x2e/0x60
Feb 24 21:11:29 box05 kernel: [  600.531129]  [<ffffffff8114e23c>] wb_do_writeback+0x2c/0xc0
Feb 24 21:11:29 box05 kernel: [  600.531135]  [<ffffffff8114e308>] bdi_writeback_task+0x38/0xc0
Feb 24 21:11:29 box05 kernel: [  600.531140]  [<ffffffff810fe870>] ? bdi_start_fn+0x0/0x100
Feb 24 21:11:29 box05 kernel: [  600.531145]  [<ffffffff810fe8f7>] bdi_start_fn+0x87/0x100
Feb 24 21:11:29 box05 kernel: [  600.531150]  [<ffffffff810fe870>] ? bdi_start_fn+0x0/0x100
Feb 24 21:11:29 box05 kernel: [  600.531154]  [<ffffffff8107f59e>] kthread+0x8e/0xa0
Feb 24 21:11:29 box05 kernel: [  600.531159]  [<ffffffff8101306a>] child_rip+0xa/0x20
Feb 24 21:11:29 box05 kernel: [  600.531164]  [<ffffffff8107f510>] ? kthread+0x0/0xa0
Feb 24 21:11:29 box05 kernel: [  600.531168]  [<ffffffff81013060>] ? child_rip+0x0/0x20