From: Ben Greear on
This is on my custom-compiled kernel, with my proprietary module included,
(ie, tainted), so feel free to ignore.

OS is Fedora 11, 64-bit.

I was running oprofile on a system under heavy network load. Once,
the machine rebooted when I clicked 'Stop' in oprof_start. I added
serial console and did some more testing. Normally stop works fine,
but one time, the whole system was totally locked (as far as I could tell)
for several minutes..then miraculously recovered. I noticed this in
'dmesg':

INFO: task events/1:28 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/1 D ffff88033096b480 0 28 2 0x00000000
ffff88033213bce0 0000000000000046 ffff88033213bcb0 ffff880332128f40
ffff88032ab39e80 ffff880332129200 0000000000000002 0000000000000001
ffff88033213bce0 ffff88033213bfd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff810386d2>] ? finish_task_switch+0x4a/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/2:29 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/2 D 0000000000000002 0 29 2 0x00000000
ffff88033213dce0 0000000000000046 ffff880001a8fee0 ffff8803321296e0
ffff88033209db80 ffff8803321299a0 0000000000000000 0000000000004158
0000000100000c00 ffff88033213dfd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff81038707>] ? finish_task_switch+0x7f/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/3:30 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/3 D 0000000000000003 0 30 2 0x00000000
ffff88033213fce0 0000000000000046 ffff880001acfee0 ffff880332129e80
ffff8803320d8000 ffff88033212a140 0000000000000000 0000000000004158
0000000100000c00 ffff88033213ffd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff81038707>] ? finish_task_switch+0x7f/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/4:31 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/4 D ffff880322448000 0 31 2 0x00000000
ffff880332141ce0 0000000000000046 ffff880332128000 ffff88033212a620
ffff88032ab387a0 ffff88033212a8e0 ffff880332141cc0 0000000000000046
ffff880332141cd0 ffff880332141fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff810386d2>] ? finish_task_switch+0x4a/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/5:32 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/5 D 0000000000000005 0 32 2 0x00000000
ffff880332143ce0 0000000000000046 ffff880001b4fee0 ffff88033212adc0
ffff8803320dbd00 ffff88033212b080 ffff880332143cc0 0000000000000046
0000000132143cd0 ffff880332143fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff81038707>] ? finish_task_switch+0x7f/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/6:33 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/6 D 0000000000000006 0 33 2 0x00000000
ffff880332145ce0 0000000000000046 ffff880001b8fee0 ffff88033212b560
ffff8803320ddb80 ffff88033212b820 ffff880332145cc0 0000000000000046
0000000132145cd0 ffff880332145fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff810aafd4>] ? refresh_cpu_vm_stats+0x105/0x146
[<ffffffff8104c1eb>] ? mod_timer+0x1e/0x20
[<ffffffff8104c204>] ? add_timer+0x17/0x19
[<ffffffff8105334b>] ? queue_delayed_work_on+0x91/0xa1
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task events/7:34 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
events/7 D 0000000000000007 0 34 2 0x00000000
ffff880332147ce0 0000000000000046 ffff880001bcfee0 ffff88033212bd00
ffff880332128000 ffff88033212bfc0 0000000000000000 0000000000004041
0000000100000800 ffff880332147fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff813de1ba>] ? _raw_spin_unlock_irq+0x34/0x3f
[<ffffffff81038707>] ? finish_task_switch+0x7f/0xa1
[<ffffffff8103510c>] ? need_resched+0x1e/0x28
[<ffffffff813dc808>] ? schedule+0x4cf/0x4e6
[<ffffffffa025f855>] ? wq_sync_buffer+0x0/0x84 [oprofile]
[<ffffffffa025f8b9>] wq_sync_buffer+0x64/0x84 [oprofile]
[<ffffffff810534c6>] worker_thread+0x112/0x1ba
[<ffffffff81056344>] ? autoremove_wake_function+0x0/0x38
[<ffffffff810533b4>] ? worker_thread+0x0/0x1ba
[<ffffffff81056130>] kthread+0x69/0x71
[<ffffffff8100a8e4>] kernel_thread_helper+0x4/0x10
[<ffffffff810560c7>] ? kthread+0x0/0x71
[<ffffffff8100a8e0>] ? kernel_thread_helper+0x0/0x10
INFO: task rsyslogd:8499 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
rsyslogd D 0000000000000007 0 8499 1 0x00000080
ffff8803186c9cc8 0000000000000082 ffffffff8141b2c0 ffff880322535b80
ffff880332128000 ffff880322535e40 0000000000000050 0000000000000000
0000000100000000 ffff8803186c9fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff8109ab22>] ? generic_file_aio_write+0x85/0xa1
[<ffffffff81143b50>] ? ext4_file_write+0x90/0xa0
[<ffffffffa02601d4>] task_exit_notify+0x11/0x15 [oprofile]
[<ffffffff813e105a>] notifier_call_chain+0x33/0x5b
[<ffffffff8105a5ce>] __blocking_notifier_call_chain+0x4d/0x6a
[<ffffffff8105a5fa>] blocking_notifier_call_chain+0xf/0x11
[<ffffffff8105d209>] profile_task_exit+0x15/0x17
[<ffffffff81045144>] do_exit+0x25/0x679
[<ffffffff810e0190>] ? path_put+0x1d/0x22
[<ffffffff81083b91>] ? audit_syscall_entry+0xfe/0x12a
[<ffffffff81045855>] complete_and_exit+0x0/0x1e
[<ffffffff81009ac2>] system_call_fastpath+0x16/0x1b
INFO: task ip:8931 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
ip D 0000000000000007 0 8931 8930 0x00000080
ffff880318351c98 0000000000000082 ffff880318351c58 ffff88031e1f8f40
ffff880332128000 ffff88031e1f9200 0000000000000000 0000000000000000
0000000100000000 ffff880318351fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff81099e36>] ? wake_up_page+0x20/0x25
[<ffffffff81099e87>] ? unlock_page+0xf/0x11
[<ffffffff810ae0b9>] ? __do_fault+0x34b/0x388
[<ffffffff8132d2f2>] ? __sys_recvmsg+0x18d/0x226
[<ffffffffa02601d4>] task_exit_notify+0x11/0x15 [oprofile]
[<ffffffff813e105a>] notifier_call_chain+0x33/0x5b
[<ffffffff8105a5ce>] __blocking_notifier_call_chain+0x4d/0x6a
[<ffffffff8105a5fa>] blocking_notifier_call_chain+0xf/0x11
[<ffffffff8105d209>] profile_task_exit+0x15/0x17
[<ffffffff81045144>] do_exit+0x25/0x679
[<ffffffff813e0f18>] ? do_page_fault+0x278/0x287
[<ffffffff8104582c>] sys_exit_group+0x0/0x16
[<ffffffff8104583e>] sys_exit_group+0x12/0x16
[<ffffffff81009ac2>] system_call_fastpath+0x16/0x1b
INFO: task ps:8933 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
ps D 0000000000000001 0 8933 8932 0x00000080
ffff88030e871c98 0000000000000086 ffff88030e871c58 ffff88031e1f9e80
ffff88033209bd00 ffff88031e1fa140 ffff88030e871c68 ffffffff81034fb4
000000010e871cb8 ffff88030e871fd8 ffffffffa02650c0 0000000000000246
Call Trace:
[<ffffffff81034fb4>] ? task_rq_unlock+0xc/0xe
[<ffffffff813dd0a9>] __mutex_lock_common+0x242/0x3ac
[<ffffffff81056355>] ? autoremove_wake_function+0x11/0x38
[<ffffffff813dd253>] __mutex_lock_slowpath+0x14/0x16
[<ffffffff813dd2c2>] mutex_lock+0x27/0x3e
[<ffffffffa025fd7c>] sync_buffer+0x2d/0x3fe [oprofile]
[<ffffffff81099e36>] ? wake_up_page+0x20/0x25
[<ffffffff81099e87>] ? unlock_page+0xf/0x11
[<ffffffff810ae0b9>] ? __do_fault+0x34b/0x388
[<ffffffffa02601d4>] task_exit_notify+0x11/0x15 [oprofile]
[<ffffffff813e105a>] notifier_call_chain+0x33/0x5b
[<ffffffff8105a5ce>] __blocking_notifier_call_chain+0x4d/0x6a
[<ffffffff8105a5fa>] blocking_notifier_call_chain+0xf/0x11
[<ffffffff8105d209>] profile_task_exit+0x15/0x17
[<ffffffff81045144>] do_exit+0x25/0x679
[<ffffffff813e0f18>] ? do_page_fault+0x278/0x287
[<ffffffff8104582c>] sys_exit_group+0x0/0x16
[<ffffffff8104583e>] sys_exit_group+0x12/0x16
[<ffffffff81009ac2>] system_call_fastpath+0x16/0x1b


Thanks,
Ben

--
Ben Greear <greearb(a)candelatech.com>
Candela Technologies Inc http://www.candelatech.com

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