On Thu, Feb 18, 2016 at 01:35:24PM +0100, Christian Rohmann wrote:

On 02/14/2016 11:42 PM, Roman Mamedov wrote:

quoted

FWIW I had a persistently repeating deadlock on 4.1 and 4.3, but
after upgrade to 4.4 it no longer happens.

Apparently also with 4.4 there is some sort of blocking happening ...
just at 38580:

OK, what does 'sysrq-w' say?

Thanks,

-liubo

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[Wed Feb 17 16:43:48 2016] INFO: task btrfs-cleaner:38580 blocked for
more than 120 seconds.
[Wed Feb 17 16:43:48 2016]       Not tainted 4.4.0-customkernel #1
[Wed Feb 17 16:43:48 2016] "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Wed Feb 17 16:43:48 2016] btrfs-cleaner   D ffff882c27295dc0     0
38580      2 0x00000000
[Wed Feb 17 16:43:48 2016]  ffff882c16fa6480 ffff88161a980280
ffff882a3d744000 ffff882a3d743df8
[Wed Feb 17 16:43:48 2016]  ffff8815fead7104 ffff882c16fa6480
00000000ffffffff ffff8815fead7108
[Wed Feb 17 16:43:48 2016]  ffffffff81559a31 ffff8815fead7100
ffffffff81559cba ffffffff8155b5a0
[Wed Feb 17 16:43:48 2016] Call Trace:
[Wed Feb 17 16:43:48 2016]  [<ffffffff81559a31>] ? schedule+0x31/0x80
[Wed Feb 17 16:43:48 2016]  [<ffffffff81559cba>] ?
schedule_preempt_disabled+0xa/0x10
[Wed Feb 17 16:43:48 2016]  [<ffffffff8155b5a0>] ?
__mutex_lock_slowpath+0x90/0x110
[Wed Feb 17 16:43:48 2016]  [<ffffffff8155b63b>] ? mutex_lock+0x1b/0x30
[Wed Feb 17 16:43:48 2016]  [<ffffffffa01bf51e>] ?
btrfs_delete_unused_bgs+0xee/0x3f0 [btrfs]
[Wed Feb 17 16:43:48 2016]  [<ffffffff81559396>] ? __schedule+0x286/0x8f0
[Wed Feb 17 16:43:48 2016]  [<ffffffffa01c6ff7>] ?
cleaner_kthread+0x1a7/0x200 [btrfs]
[Wed Feb 17 16:43:48 2016]  [<ffffffffa01c6e50>] ?
check_leaf+0x340/0x340 [btrfs]
[Wed Feb 17 16:43:48 2016]  [<ffffffff8108df6f>] ? kthread+0xcf/0xf0
[Wed Feb 17 16:43:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50
[Wed Feb 17 16:43:48 2016]  [<ffffffff8155d74f>] ? ret_from_fork+0x3f/0x70
[Wed Feb 17 16:43:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50

[Wed Feb 17 17:23:48 2016] INFO: task btrfs-cleaner:38580 blocked for
more than 120 seconds.
[Wed Feb 17 17:23:48 2016]       Not tainted 4.4.0-customkernel #1
[Wed Feb 17 17:23:48 2016] "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Wed Feb 17 17:23:48 2016] btrfs-cleaner   D ffff881627a35dc0     0
38580      2 0x00000000
[Wed Feb 17 17:23:48 2016]  ffff882c16fa6480 ffff88161a956f00
ffff882a3d744000 ffff882a3d743df8
[Wed Feb 17 17:23:48 2016]  ffff8815fead7104 ffff882c16fa6480
00000000ffffffff ffff8815fead7108
[Wed Feb 17 17:23:48 2016]  ffffffff81559a31 ffff8815fead7100
ffffffff81559cba ffffffff8155b5a0
[Wed Feb 17 17:23:48 2016] Call Trace:
[Wed Feb 17 17:23:48 2016]  [<ffffffff81559a31>] ? schedule+0x31/0x80
[Wed Feb 17 17:23:48 2016]  [<ffffffff81559cba>] ?
schedule_preempt_disabled+0xa/0x10
[Wed Feb 17 17:23:48 2016]  [<ffffffff8155b5a0>] ?
__mutex_lock_slowpath+0x90/0x110
[Wed Feb 17 17:23:48 2016]  [<ffffffff8155b63b>] ? mutex_lock+0x1b/0x30
[Wed Feb 17 17:23:48 2016]  [<ffffffffa01bf51e>] ?
btrfs_delete_unused_bgs+0xee/0x3f0 [btrfs]
[Wed Feb 17 17:23:48 2016]  [<ffffffff81559396>] ? __schedule+0x286/0x8f0
[Wed Feb 17 17:23:48 2016]  [<ffffffffa01c6ff7>] ?
cleaner_kthread+0x1a7/0x200 [btrfs]
[Wed Feb 17 17:23:48 2016]  [<ffffffffa01c6e50>] ?
check_leaf+0x340/0x340 [btrfs]
[Wed Feb 17 17:23:48 2016]  [<ffffffff8108df6f>] ? kthread+0xcf/0xf0
[Wed Feb 17 17:23:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50
[Wed Feb 17 17:23:48 2016]  [<ffffffff8155d74f>] ? ret_from_fork+0x3f/0x70
[Wed Feb 17 17:23:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50

[Wed Feb 17 17:57:48 2016] INFO: task btrfs-cleaner:38580 blocked for
more than 120 seconds.
[Wed Feb 17 17:57:48 2016]       Not tainted 4.4.0-customkernel #1
[Wed Feb 17 17:57:48 2016] "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Wed Feb 17 17:57:48 2016] btrfs-cleaner   D ffff881627a95dc0     0
38580      2 0x00000000
[Wed Feb 17 17:57:48 2016]  ffff882c16fa6480 ffff88161a980fc0
ffff882a3d744000 ffff882a3d743df8
[Wed Feb 17 17:57:48 2016]  ffff8815fead7104 ffff882c16fa6480
00000000ffffffff ffff8815fead7108
[Wed Feb 17 17:57:48 2016]  ffffffff81559a31 ffff8815fead7100
ffffffff81559cba ffffffff8155b5a0
[Wed Feb 17 17:57:48 2016] Call Trace:
[Wed Feb 17 17:57:48 2016]  [<ffffffff81559a31>] ? schedule+0x31/0x80
[Wed Feb 17 17:57:48 2016]  [<ffffffff81559cba>] ?
schedule_preempt_disabled+0xa/0x10
[Wed Feb 17 17:57:48 2016]  [<ffffffff8155b5a0>] ?
__mutex_lock_slowpath+0x90/0x110
[Wed Feb 17 17:57:48 2016]  [<ffffffff8155b63b>] ? mutex_lock+0x1b/0x30
[Wed Feb 17 17:57:48 2016]  [<ffffffffa01bf51e>] ?
btrfs_delete_unused_bgs+0xee/0x3f0 [btrfs]
[Wed Feb 17 17:57:48 2016]  [<ffffffff81559396>] ? __schedule+0x286/0x8f0
[Wed Feb 17 17:57:48 2016]  [<ffffffffa01c6ff7>] ?
cleaner_kthread+0x1a7/0x200 [btrfs]
[Wed Feb 17 17:57:48 2016]  [<ffffffffa01c6e50>] ?
check_leaf+0x340/0x340 [btrfs]
[Wed Feb 17 17:57:48 2016]  [<ffffffff8108df6f>] ? kthread+0xcf/0xf0
[Wed Feb 17 17:57:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50
[Wed Feb 17 17:57:48 2016]  [<ffffffff8155d74f>] ? ret_from_fork+0x3f/0x70
[Wed Feb 17 17:57:48 2016]  [<ffffffff8108dea0>] ? kthread_park+0x50/0x50


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