[BUG] Hang (deadlock?) inside iscsi_if_rx

[BUG] Hang (deadlock?) inside iscsi_if_rx

[Sasha Levin]

Hi all,

I got the following hang when running trinity under KVM tool:

[ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
[ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
[ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
[ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
[ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
[ 2520.832838] Call Trace:
[ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
[ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
[ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
[ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
[ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
[ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
[ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
[ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
[ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
[ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
[ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
[ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
[ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
[ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
[ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
[ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
[ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
[ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
[ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
[ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
[ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
[ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
[ 2520.873039] 1 lock held by trinity/31986:
[ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
[ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks

>From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.

Thanks.

-- 

Sasha.

Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Mike Christie]

On 01/24/2012 08:30 AM, Sasha Levin wrote:
> Hi all,
> 
> I got the following hang when running trinity under KVM tool:
> 
> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
> [ 2520.832838] Call Trace:
> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
> [ 2520.873039] 1 lock held by trinity/31986:
> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
> 
> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
> 

What does the trinity test do? Does it write random junk to netlink
sockets to test the kernel handlers or were you actually stressing the
creation of targets. If the latter what driver were you trying to create
targets with (iscsi_tcp, bnx2i, etc)?

Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Mike Christie]

On 01/24/2012 10:29 AM, Mike Christie wrote:
> On 01/24/2012 08:30 AM, Sasha Levin wrote:
>> Hi all,
>>
>> I got the following hang when running trinity under KVM tool:
>>
>> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
>> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
>> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
>> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
>> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
>> [ 2520.832838] Call Trace:
>> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
>> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
>> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
>> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
>> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
>> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
>> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
>> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
>> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
>> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
>> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
>> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
>> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
>> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
>> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
>> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
>> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
>> [ 2520.873039] 1 lock held by trinity/31986:
>> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
>>
>> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
>>
> 
> What does the trinity test do? Does it write random junk to netlink
> sockets to test the kernel handlers or were you actually stressing the
> creation of targets. If the latter what driver were you trying to create
> targets with (iscsi_tcp, bnx2i, etc)?


Oh yeah, for the random type of test, how much data does userspace write?

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Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Sasha Levin]

On Tue, Jan 24, 2012 at 11:29 AM, Mike Christie <michaelc@cs.wisc.edu> wrote:
> On 01/24/2012 08:30 AM, Sasha Levin wrote:
>> Hi all,
>>
>> I got the following hang when running trinity under KVM tool:
>>
>> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
>> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
>> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
>> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
>> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
>> [ 2520.832838] Call Trace:
>> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
>> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
>> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
>> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
>> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
>> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
>> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
>> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
>> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
>> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
>> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
>> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
>> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
>> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
>> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
>> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
>> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
>> [ 2520.873039] 1 lock held by trinity/31986:
>> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
>>
>> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
>>
>
> What does the trinity test do? Does it write random junk to netlink
> sockets to test the kernel handlers or were you actually stressing the
> creation of targets. If the latter what driver were you trying to create
> targets with (iscsi_tcp, bnx2i, etc)?

It basically just writes junk into sockets. In this case it was just a
large chunk of it written into the netlink socket.

I'm not directly trying to stress iscsi, though it might have happened
somehow during the test accidentally (but thats not probable).
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Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Mike Christie]

On 01/24/2012 10:51 AM, Sasha Levin wrote:
> On Tue, Jan 24, 2012 at 11:29 AM, Mike Christie <michaelc@cs.wisc.edu> wrote:
>> On 01/24/2012 08:30 AM, Sasha Levin wrote:
>>> Hi all,
>>>
>>> I got the following hang when running trinity under KVM tool:
>>>
>>> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
>>> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
>>> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
>>> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
>>> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
>>> [ 2520.832838] Call Trace:
>>> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
>>> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
>>> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>>> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
>>> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>>> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
>>> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>>> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
>>> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
>>> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
>>> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
>>> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
>>> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
>>> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
>>> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>>> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
>>> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
>>> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>>> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
>>> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
>>> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
>>> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
>>> [ 2520.873039] 1 lock held by trinity/31986:
>>> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>>> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
>>>
>>> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
>>>
>>
>> What does the trinity test do? Does it write random junk to netlink
>> sockets to test the kernel handlers or were you actually stressing the
>> creation of targets. If the latter what driver were you trying to create
>> targets with (iscsi_tcp, bnx2i, etc)?
> 
> It basically just writes junk into sockets. In this case it was just a
> large chunk of it written into the netlink socket.
> 

Could you tell me what arguments you used?

Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Mike Christie]

On 01/25/2012 08:17 PM, Mike Christie wrote:
> On 01/24/2012 10:51 AM, Sasha Levin wrote:
>> On Tue, Jan 24, 2012 at 11:29 AM, Mike Christie <michaelc@cs.wisc.edu> wrote:
>>> On 01/24/2012 08:30 AM, Sasha Levin wrote:
>>>> Hi all,
>>>>
>>>> I got the following hang when running trinity under KVM tool:
>>>>
>>>> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
>>>> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
>>>> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
>>>> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
>>>> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
>>>> [ 2520.832838] Call Trace:
>>>> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
>>>> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
>>>> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>>>> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
>>>> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
>>>> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
>>>> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>>>> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
>>>> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
>>>> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
>>>> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
>>>> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
>>>> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
>>>> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
>>>> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>>>> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
>>>> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
>>>> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
>>>> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
>>>> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
>>>> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
>>>> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
>>>> [ 2520.873039] 1 lock held by trinity/31986:
>>>> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
>>>> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
>>>>
>>>> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
>>>>
>>>
>>> What does the trinity test do? Does it write random junk to netlink
>>> sockets to test the kernel handlers or were you actually stressing the
>>> creation of targets. If the latter what driver were you trying to create
>>> targets with (iscsi_tcp, bnx2i, etc)?
>>
>> It basically just writes junk into sockets. In this case it was just a
>> large chunk of it written into the netlink socket.
>>
> 
> Could you tell me what arguments you used?

And what kernel was this with?

Re: [BUG] Hang (deadlock?) inside iscsi_if_rx

[Sasha Levin]

On Wed, 2012-01-25 at 20:20 -0600, Mike Christie wrote:
> On 01/25/2012 08:17 PM, Mike Christie wrote:
> > On 01/24/2012 10:51 AM, Sasha Levin wrote:
> >> On Tue, Jan 24, 2012 at 11:29 AM, Mike Christie <michaelc@cs.wisc.edu> wrote:
> >>> On 01/24/2012 08:30 AM, Sasha Levin wrote:
> >>>> Hi all,
> >>>>
> >>>> I got the following hang when running trinity under KVM tool:
> >>>>
> >>>> [ 2520.824250] INFO: task trinity:31986 blocked for more than 120 seconds.
> >>>> [ 2520.825513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >>>> [ 2520.826983] trinity         D 0000000000000000  5504 31986   2767 0x00000004
> >>>> [ 2520.828416]  ffff88000a21ba98 0000000000000086 ffff88000a3f8000 ffff88000a3f8000
> >>>> [ 2520.829892]  00000000001d4340 ffff88000a21bfd8 ffff88000a21a000 00000000001d4340
> >>>> [ 2520.831380]  00000000001d4340 00000000001d4340 ffff88000a21bfd8 00000000001d4340
> >>>> [ 2520.832838] Call Trace:
> >>>> [ 2520.837089]  [<ffffffff8265297a>] schedule+0x3a/0x50
> >>>> [ 2520.837983]  [<ffffffff82651049>] __mutex_lock_common+0x209/0x5b0
> >>>> [ 2520.839181]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
> >>>> [ 2520.840232]  [<ffffffff81053943>] ? sched_clock+0x13/0x20
> >>>> [ 2520.841242]  [<ffffffff81af64f3>] ? iscsi_if_rx+0x23/0xa00
> >>>> [ 2520.842271]  [<ffffffff82651430>] mutex_lock_nested+0x40/0x50
> >>>> [ 2520.843353]  [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
> >>>> [ 2520.844461]  [<ffffffff810dfffd>] ? sub_preempt_count+0x9d/0xd0
> >>>> [ 2520.845576]  [<ffffffff82654130>] ? _raw_read_unlock+0x30/0x60
> >>>> [ 2520.846705]  [<ffffffff8221632e>] netlink_unicast+0x1ae/0x1f0
> >>>> [ 2520.847790]  [<ffffffff82216ae7>] netlink_sendmsg+0x227/0x350
> >>>> [ 2520.848884]  [<ffffffff821a490d>] ? sock_update_netprioidx+0xdd/0x1b0
> >>>> [ 2520.850105]  [<ffffffff821a4882>] ? sock_update_netprioidx+0x52/0x1b0
> >>>> [ 2520.851282]  [<ffffffff8219e376>] sock_aio_write+0x166/0x180
> >>>> [ 2520.852317]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
> >>>> [ 2520.853342]  [<ffffffff811d0b1a>] do_sync_write+0xda/0x120
> >>>> [ 2520.854347]  [<ffffffff81109c42>] ? lock_release_holdtime+0xb2/0x160
> >>>> [ 2520.855533]  [<ffffffff810dfe51>] ? get_parent_ip+0x11/0x50
> >>>> [ 2520.856569]  [<ffffffff817914e7>] ? security_file_permission+0x27/0xb0
> >>>> [ 2520.857756]  [<ffffffff811d0ccc>] vfs_write+0x16c/0x180
> >>>> [ 2520.858713]  [<ffffffff811d0dcf>] sys_write+0x4f/0xa0
> >>>> [ 2520.859680]  [<ffffffff826553f9>] system_call_fastpath+0x16/0x1b
> >>>> [ 2520.873039] 1 lock held by trinity/31986:
> >>>> [ 2520.873801]  #0:  (rx_queue_mutex){+.+...}, at: [<ffffffff81af64f3>] iscsi_if_rx+0x23/0xa00
> >>>> [ 2520.875587] Kernel panic - not syncing: hung_task: blocked tasks
> >>>>
> >>>> From looking at the logs, there were two instances of the fuzzer blocked on a write() to a netlink socket. There are no iSCSI targets anywhere on the network.
> >>>>
> >>>
> >>> What does the trinity test do? Does it write random junk to netlink
> >>> sockets to test the kernel handlers or were you actually stressing the
> >>> creation of targets. If the latter what driver were you trying to create
> >>> targets with (iscsi_tcp, bnx2i, etc)?
> >>
> >> It basically just writes junk into sockets. In this case it was just a
> >> large chunk of it written into the netlink socket.
> >>
> > 
> > Could you tell me what arguments you used?
> 
> And what kernel was this with?

It was the linux-next kernel from that day, I can't find the logs of
that socket though, will have to recreate it.

I did debug the issue and found it's the result of iscsi_if_send_reply
returning -ESRCH which makes us hang in the do {} while(); loop forever.

I've sent a patch to deal with that.

-- 

Sasha.