rhel6.4_x64 INFO: task flush-8:0:2545 blocked for more than 120 seconds.

what does this mean?is there some hardware is worked unusual?it's in fio testing when this messages apeared：

Sep 15 13:52:51 m12 kernel: INFO: task flush-8:0:2545 blocked for more than 120 seconds.
Sep 15 13:52:51 m12 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Sep 15 13:52:51 m12 kernel: flush-8:0 D ffff88207fc29400 0 2545 2 0x00000000
Sep 15 13:52:51 m12 kernel: ffff88204eed5910 0000000000000046 0000000000000000 ffff882053badc40
Sep 15 13:52:51 m12 kernel: 0000000000000082 0000000000000000 ffff88203b1c7c64 0000000000000082
Sep 15 13:52:51 m12 kernel: ffff88204d430638 ffff88204eed5fd8 000000000000fb88 ffff88204d430638
Sep 15 13:52:51 m12 kernel: Call Trace:
Sep 15 13:52:51 m12 kernel: [] io_schedule+0x73/0xc0
Sep 15 13:52:51 m12 kernel: [] get_request_wait+0x108/0x1d0
Sep 15 13:52:51 m12 kernel: [] ? autoremove_wake_function+0x0/0x40
Sep 15 13:52:51 m12 kernel: [] ? elv_merge+0x1cb/0x200
Sep 15 13:52:51 m12 kernel: [] blk_queue_bio+0x7d/0x5a0
Sep 15 13:52:51 m12 kernel: [] ? ftrace_raw_event_id_block_bio+0xf2/0x100
Sep 15 13:52:51 m12 kernel: [] generic_make_request+0x25e/0x530
Sep 15 13:52:51 m12 kernel: [] submit_bio+0x8d/0x120
Sep 15 13:52:51 m12 kernel: [] mpage_bio_submit+0x27/0x30
Sep 15 13:52:51 m12 kernel: [] mpage_writepages+0x53/0x70
Sep 15 13:52:51 m12 kernel: [] ? ext2_get_block+0x0/0x50 [ext2]
Sep 15 13:52:51 m12 kernel: [] ext2_writepages+0x15/0x20 [ext2]
Sep 15 13:52:51 m12 kernel: [] do_writepages+0x21/0x40
Sep 15 13:52:51 m12 kernel: [] writeback_single_inode+0xdd/0x290
Sep 15 13:52:51 m12 kernel: [] writeback_sb_inodes+0xce/0x180
Sep 15 13:52:51 m12 kernel: [] writeback_inodes_wb+0xab/0x1b0
Sep 15 13:52:51 m12 kernel: [] wb_writeback+0x29b/0x3f0
Sep 15 13:52:51 m12 kernel: [] ? thread_return+0x4e/0x76e
Sep 15 13:52:51 m12 kernel: [] ? del_timer_sync+0x22/0x30
Sep 15 13:52:51 m12 kernel: [] wb_do_writeback+0x199/0x240
Sep 15 13:52:51 m12 kernel: [] bdi_writeback_task+0x63/0x1b0
Sep 15 13:52:51 m12 kernel: [] ? bit_waitqueue+0x17/0xd0
Sep 15 13:52:51 m12 kernel: [] ? bdi_start_fn+0x0/0x100
Sep 15 13:52:51 m12 kernel: [] bdi_start_fn+0x86/0x100
Sep 15 13:52:51 m12 kernel: [] ? bdi_start_fn+0x0/0x100
Sep 15 13:52:51 m12 kernel: [] kthread+0x96/0xa0
Sep 15 13:52:51 m12 kernel: [] child_rip+0xa/0x20
Sep 15 13:52:51 m12 kernel: [] ? kthread+0x0/0xa0
Sep 15 13:52:51 m12 kernel: [] ? child_rip+0x0/0x20
Sep 15 13:52:51 m12 kernel: INFO: task auditd:3316 blocked for more than 120 seconds.
Sep 15 13:52:51 m12 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Sep 15 13:52:51 m12 kernel: auditd D ffff88207fc29400 0 3316 1 0x10000000
Sep 15 13:52:51 m12 kernel: ffff88204c95fb68 0000000000000086 0000000000000000 ffff882053badc40
Sep 15 13:52:51 m12 kernel: 0000000000000086 0000000000000000 ffff88203db6f304 0000000000000086
Sep 15 13:52:51 m12 kernel: ffff88204f5b65f8 ffff88204c95ffd8 000000000000fb88 ffff88204f5b65f8
Sep 15 13:52:51 m12 kernel: Call Trace:
Sep 15 13:52:51 m12 kernel: [] io_schedule+0x73/0xc0
Sep 15 13:52:51 m12 kernel: [] get_request_wait+0x108/0x1d0
Sep 15 13:52:51 m12 kernel: [] ? autoremove_wake_function+0x0/0x40
Sep 15 13:52:51 m12 kernel: [] ? elv_merge+0x1cb/0x200
Sep 15 13:52:51 m12 kernel: [] blk_queue_bio+0x7d/0x5a0
Sep 15 13:52:51 m12 kernel: [] ? ftrace_raw_event_id_block_bio+0xf2/0x100
Sep 15 13:52:51 m12 kernel: [] generic_make_request+0x25e/0x530
Sep 15 13:52:51 m12 kernel: [] ? wake_up_state+0x10/0x20
Sep 15 13:52:51 m12 kernel: [] submit_bio+0x8d/0x120
Sep 15 13:52:51 m12 kernel: [] mpage_bio_submit+0x27/0x30
Sep 15 13:52:51 m12 kernel: [] mpage_writepages+0x53/0x70
Sep 15 13:52:51 m12 kernel: [] ? ext2_get_block+0x0/0x50 [ext2]
Sep 15 13:52:51 m12 kernel: [] ext2_writepages+0x15/0x20 [ext2]
Sep 15 13:52:51 m12 kernel: [] do_writepages+0x21/0x40
Sep 15 13:52:51 m12 kernel: [] __filemap_fdatawrite_range+0x5b/0x60
Sep 15 13:52:51 m12 kernel: [] ? trace_nowake_buffer_unlock_commit+0x43/0x60
Sep 15 13:52:51 m12 kernel: [] filemap_write_and_wait_range+0x5a/0x90
Sep 15 13:52:51 m12 kernel: [] vfs_fsync_range+0x7e/0xe0
Sep 15 13:52:51 m12 kernel: [] vfs_fsync+0x1d/0x20
Sep 15 13:52:51 m12 kernel: [] do_fsync+0x3e/0x60
Sep 15 13:52:51 m12 kernel: [] sys_fsync+0x10/0x20
Sep 15 13:52:51 m12 kernel: [] tracesys+0xd9/0xde
Sep 15 13:52:51 m12 kernel: INFO: task sadc:5890 blocked for more than 120 seconds.
Sep 15 13:52:51 m12 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Sep 15 13:52:51 m12 kernel: sadc D ffff88207fc2b600 0 5890 5886 0x10000084
Sep 15 13:52:51 m12 kernel: ffff881d909ebb68 0000000000000082 0000000000000000 ffff882053badc40
Sep 15 13:52:51 m12 kernel: 0000000000000086 0000000000000000 ffff88203ec5759c 0000000000000086
Sep 15 13:52:51 m12 kernel: ffff881f7525baf8 ffff881d909ebfd8 000000000000fb88 ffff881f7525baf8
Sep 15 13:52:51 m12 kernel: Call Trace:
Sep 15 13:52:51 m12 kernel: [] io_schedule+0x73/0xc0
Sep 15 13:52:51 m12 kernel: [] get_request_wait+0x108/0x1d0
Sep 15 13:52:51 m12 kernel: [] ? autoremove_wake_function+0x0/0x40
Sep 15 13:52:51 m12 kernel: [] ? elv_merge+0x1cb/0x200
Sep 15 13:52:51 m12 kernel: [] blk_queue_bio+0x7d/0x5a0
Sep 15 13:52:51 m12 kernel: [] ? ftrace_raw_event_id_block_bio+0xf2/0x100
Sep 15 13:52:51 m12 kernel: [] generic_make_request+0x25e/0x530
Sep 15 13:52:51 m12 kernel: [] submit_bio+0x8d/0x120
Sep 15 13:52:51 m12 kernel: [] mpage_bio_submit+0x27/0x30
Sep 15 13:52:51 m12 kernel: [] mpage_writepages+0x53/0x70
Sep 15 13:52:51 m12 kernel: [] ? ext2_get_block+0x0/0x50 [ext2]
Sep 15 13:52:51 m12 kernel: [] ext2_writepages+0x15/0x20 [ext2]
Sep 15 13:52:51 m12 kernel: [] do_writepages+0x21/0x40
Sep 15 13:52:51 m12 kernel: [] __filemap_fdatawrite_range+0x5b/0x60
Sep 15 13:52:51 m12 kernel: [] ? trace_nowake_buffer_unlock_commit+0x43/0x60
Sep 15 13:52:51 m12 kernel: [] filemap_write_and_wait_range+0x5a/0x90
Sep 15 13:52:51 m12 kernel: [] vfs_fsync_range+0x7e/0xe0
Sep 15 13:52:51 m12 kernel: [] vfs_fsync+0x1d/0x20
Sep 15 13:52:51 m12 kernel: [] do_fsync+0x3e/0x60
Sep 15 13:52:51 m12 kernel: [] sys_fdatasync+0x13/0x20
Sep 15 13:52:51 m12 kernel: [] tracesys+0xd9/0xde
Sep 15 13:56:51 m12 kernel: INFO: task flush-8:0:2545 blocked for more than 120 seconds.
Sep 15 13:56:51 m12 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Sep 15 13:56:51 m12 kernel: flush-8:0 D 00000000ffffffff 0 2545 2 0x00000000
Sep 15 13:56:51 m12 kernel: ffff88204eed5910 0000000000000046 0000000000000082 ffff882053badc40
Sep 15 13:56:51 m12 kernel: 0000000000000082 0000000000000000 ffff88203db299e0 0000000000000082
Sep 15 13:56:51 m12 kernel: ffff88204d430638 ffff88204eed5fd8 000000000000fb88 ffff88204d430638
Sep 15 13:56:51 m12 kernel: Call Trace:
Sep 15 13:56:51 m12 kernel: [] ? ktime_get_ts+0xa9/0xe0
Sep 15 13:56:51 m12 kernel: [] io_schedule+0x73/0xc0
Sep 15 13:56:51 m12 kernel: [] get_request_wait+0x108/0x1d0
Sep 15 13:56:51 m12 kernel: [] ? autoremove_wake_function+0x0/0x40
Sep 15 13:56:51 m12 kernel: [] ? elv_merge+0x1cb/0x200
Sep 15 13:56:51 m12 kernel: [] blk_queue_bio+0x7d/0x5a0
Sep 15 13:56:51 m12 kernel: [] ? ftrace_raw_event_id_block_bio+0xf2/0x100
Sep 15 13:56:51 m12 kernel: [] generic_make_request+0x25e/0x530
Sep 15 13:56:51 m12 kernel: [] submit_bio+0x8d/0x120
Sep 15 13:56:51 m12 kernel: [] mpage_bio_submit+0x27/0x30
Sep 15 13:56:51 m12 kernel: [] mpage_writepages+0x53/0x70
Sep 15 13:56:51 m12 kernel: [] ? ext2_get_block+0x0/0x50 [ext2]
Sep 15 13:56:51 m12 kernel: [] ext2_writepages+0x15/0x20 [ext2]
Sep 15 13:56:51 m12 kernel: [] do_writepages+0x21/0x40
Sep 15 13:56:51 m12 kernel: [] writeback_single_inode+0xdd/0x290
Sep 15 13:56:51 m12 kernel: [] writeback_sb_inodes+0xce/0x180
Sep 15 13:56:51 m12 kernel: [] writeback_inodes_wb+0xab/0x1b0
Sep 15 13:56:51 m12 kernel: [] wb_writeback+0x29b/0x3f0
Sep 15 13:56:51 m12 kernel: [] ? thread_return+0x4e/0x76e
Sep 15 13:56:51 m12 kernel: [] ? del_timer_sync+0x22/0x30
Sep 15 13:56:51 m12 kernel: [] wb_do_writeback+0x199/0x240
Sep 15 13:56:51 m12 kernel: [] bdi_writeback_task+0x63/0x1b0
Sep 15 13:56:51 m12 kernel: [] ? bit_waitqueue+0x17/0xd0
Sep 15 13:56:51 m12 kernel: [] ? bdi_start_fn+0x0/0x100
Sep 15 13:56:51 m12 kernel: [] bdi_start_fn+0x86/0x100
Sep 15 13:56:51 m12 kernel: [] ? bdi_start_fn+0x0/0x100
Sep 15 13:56:51 m12 kernel: [] kthread+0x96/0xa0
Sep 15 13:56:51 m12 kernel: [] child_rip+0xa/0x20
Sep 15 13:56:51 m12 kernel: [] ? kthread+0x0/0xa0
Sep 15 13:56:51 m12 kernel: [] ? child_rip+0x0/0x20