May 8 14:57:25 example_server kernel: INFO: task kworker/88:2:80044 blocked for more than 120 seconds.
May 8 14:57:25 example_server kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
May 8 14:57:25 example_server kernel: kworker/88:2 D ffff88019bc5e380 0 80044 2 0x00000000
May 8 14:57:25 example_server kernel: ffff8803c5d87bf0 0000000000000046 ffff88011d666380 ffff8803c5d87fd8
May 8 14:57:25 example_server kernel: ffff8803c5d87fd8 ffff8803c5d87fd8 ffff88011d666380 ffff8803c5d87d58
May 8 14:57:25 example_server kernel: ffff8803c5d87d60 7fffffffffffffff ffff88011d666380 ffff8803c5d87dd8
May 8 14:57:25 example_server kernel: Call Trace:
May 8 14:57:25 example_server kernel: [<ffffffff8163a1c9>] schedule+0x29/0x70
May 8 14:57:25 example_server kernel: [<ffffffff81637e29>] schedule_timeout+0x209/0x2d0
May 8 14:57:25 example_server kernel: [<ffffffff8101d165>] ? native_sched_clock+0x35/0x80
May 8 14:57:25 example_server kernel: [<ffffffff8101d1b9>] ? sched_clock+0x9/0x10
May 8 14:57:25 example_server kernel: [<ffffffff8163a5a6>] wait_for_completion+0x116/0x170
May 8 14:57:25 example_server kernel: [<ffffffff810b4b00>] ? wake_up_state+0x20/0x20
May 8 14:57:25 example_server kernel: [<ffffffff810a15e8>] kthread_create_on_node+0xa8/0x140
May 8 14:57:25 example_server kernel: [<ffffffff81099ed0>] ? rescuer_thread+0x400/0x400
May 8 14:57:25 example_server kernel: [<ffffffff810995fa>] create_worker+0xea/0x250
May 8 14:57:25 example_server kernel: [<ffffffff810998f6>] manage_workers.isra.24+0xf6/0x2d0
May 8 14:57:25 example_server kernel: [<ffffffff8109a209>] worker_thread+0x339/0x400
May 8 14:57:25 example_server kernel: [<ffffffff81099ed0>] ? rescuer_thread+0x400/0x400
May 8 14:57:25 example_server kernel: [<ffffffff810a174f>] kthread+0xcf/0xe0
May 8 14:57:25 example_server kernel: [<ffffffff810a1680>] ? kthread_create_on_node+0x140/0x140
May 8 14:57:25 example_server kernel: [<ffffffff81644fd8>] ret_from_fork+0x58/0x90
May 8 14:57:25 example_server kernel: [<ffffffff810a1680>] ? kthread_create_on_node+0x140/0x140
同时在KVM虚拟机中也观察到
INFO: task jbd2/vdb5-8:1648 blocked for more than 120 seconds.
Not tainted 2.6.32-696.3.2.el6.x86_64 #1
echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
INFO: task sadc:30102 blocked for more than 120 seconds.
Not tainted 2.6.32-696.3.2.el6.x86_64 #1
echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
INFO: task jbd2/vda1-8:327 blocked for more than 120 seconds.
Not tainted 2.6.32-696.3.2.el6.x86_64 #1
echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
很多时候,在磁盘或文件系统出现异常时,会出现task XXXX blocked for more than 120 seconds.,这种现象在系统负载极高或者IO负载极高时候出现,原因是默认情况下Linux使用40%的可用内存作为文件系统缓存。当达到这个阀值之后,就会将缓存内容刷新到磁盘以实现IO同步。对于刷新数据到磁盘默认设置了120秒作为时间限制。如果IO系统不是足够快速,不能在120秒内完成数据刷新就会出现上述报警。