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From: Andy Gospodarek on 7 Apr 2010 00:10
On Apr 6, 2010, at 10:32 PM, Cong Wang <amwang(a)redhat.com> wrote:

> Andy Gospodarek wrote:
>> On Tue, Apr 06, 2010 at 12:38:16PM +0800, Cong Wang wrote:
>>> Cong Wang wrote:
>>>> Before I try to reproduce it, could you please try to replace
>>>> the 'read_lock()'
>>>> in slaves_support_netpoll() with 'read_lock_bh()'? (read_unlock()
>>>> too) Try if this helps.
>>>>
>>> Confirmed. Please use the attached patch instead, for your testing.
>>>
>>> Thanks!
>>>
>> Moving those locks to bh-locks will not resolve this. I tried that
>> yesterday and tried your new patch today without success. That
>> warning
>> is a WARN_ON_ONCE so you need to reboot to see that it is still a
>> problem. Simply unloading and loading the new module is not an
>> accurate
>> test.
>> Also, my system still hangs when removing the bonding module. I do
>> not
>> think you intended to fix this with the patch, but wanted it to be
>> clear
>> to everyone on the list.
>
>
> Actually I did reboot and then tested the module. I didn't get any
> warning.
> I just tried again today, and no warnings at all.
>
> For removing bonding module, you may need another fix of mine,
> which is to fix a potential deadlock of workqueue. Try:
>
> http://lkml.org/lkml/2010/4/1/58
>
>> You should also configure your kernel with a some of the lock
>> debugging
>> enabled. I've been using the following:
>> CONFIG_DETECT_HUNG_TASK=y
>> CONFIG_DEBUG_SPINLOCK=y
>> CONFIG_DEBUG_MUTEXES=y
>> CONFIG_DEBUG_LOCK_ALLOC=y
>> CONFIG_PROVE_LOCKING=y
>> CONFIG_LOCKDEP=y
>> CONFIG_LOCK_STAT=y
>> CONFIG_DEBUG_LOCKDEP=y
>
>
> Sure, I always keep these.
>
>> Here is the output when I remove a slave from the bond. My
>> xmit_roundrobin patch from earlier (replacing read_lock with
>> read_trylock) was applied. It might be helpful for you when
>> debugging
>> these issues.
>
>
> I don't apply your patch, just tested my patch.
>
>> Dead loop on virtual device bond0, fix it urgently!
>
> Please provide your bonding configuration and steps to reproduce it.
>

My first response in this thread provides the commands and
configuration needed to reproduce this.

> What I did is:
>
> 1. Load bonding module with "mode=0 miimon=100"
> 2. Enslave eth0 and active bond0
> 3. Load netconsole and send messages via bond0
> 4. Remove eth0 from bond0
> 5. Remove bonding module
> 6. Remove netconsole module

Thanks for sending your configuration.

What values are in /proc/sys/kernel/printk?

> And no deadlocks, no warnings.
>
> Thanks.
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From: Cong Wang on 7 Apr 2010 00:20
Andy Gospodarek wrote:
> On Apr 6, 2010, at 10:32 PM, Cong Wang <amwang(a)redhat.com> wrote:
>
>> Andy Gospodarek wrote:
>>> On Tue, Apr 06, 2010 at 12:38:16PM +0800, Cong Wang wrote:
>>>> Cong Wang wrote:
>>>>> Before I try to reproduce it, could you please try to replace
>>>>> the 'read_lock()'
>>>>> in slaves_support_netpoll() with 'read_lock_bh()'? (read_unlock()
>>>>> too) Try if this helps.
>>>>>
>>>> Confirmed. Please use the attached patch instead, for your testing.
>>>>
>>>> Thanks!
>>>>
>>> Moving those locks to bh-locks will not resolve this. I tried that
>>> yesterday and tried your new patch today without success. That
>>> warning
>>> is a WARN_ON_ONCE so you need to reboot to see that it is still a
>>> problem. Simply unloading and loading the new module is not an
>>> accurate
>>> test.
>>> Also, my system still hangs when removing the bonding module. I do
>>> not
>>> think you intended to fix this with the patch, but wanted it to be
>>> clear
>>> to everyone on the list.
>>
>> Actually I did reboot and then tested the module. I didn't get any
>> warning.
>> I just tried again today, and no warnings at all.
>>
>> For removing bonding module, you may need another fix of mine,
>> which is to fix a potential deadlock of workqueue. Try:
>>
>> http://lkml.org/lkml/2010/4/1/58
>>
>>> You should also configure your kernel with a some of the lock
>>> debugging
>>> enabled. I've been using the following:
>>> CONFIG_DETECT_HUNG_TASK=y
>>> CONFIG_DEBUG_SPINLOCK=y
>>> CONFIG_DEBUG_MUTEXES=y
>>> CONFIG_DEBUG_LOCK_ALLOC=y
>>> CONFIG_PROVE_LOCKING=y
>>> CONFIG_LOCKDEP=y
>>> CONFIG_LOCK_STAT=y
>>> CONFIG_DEBUG_LOCKDEP=y
>>
>> Sure, I always keep these.
>>
>>> Here is the output when I remove a slave from the bond. My
>>> xmit_roundrobin patch from earlier (replacing read_lock with
>>> read_trylock) was applied. It might be helpful for you when
>>> debugging
>>> these issues.
>>
>> I don't apply your patch, just tested my patch.
>>
>>> Dead loop on virtual device bond0, fix it urgently!
>> Please provide your bonding configuration and steps to reproduce it.
>>
>
> My first response in this thread provides the commands and
> configuration needed to reproduce this.


Then I should do the right thing.

>
>> What I did is:
>>
>> 1. Load bonding module with "mode=0 miimon=100"
>> 2. Enslave eth0 and active bond0
>> 3. Load netconsole and send messages via bond0
>> 4. Remove eth0 from bond0
>> 5. Remove bonding module
>> 6. Remove netconsole module
>
> Thanks for sending your configuration.
>
> What values are in /proc/sys/kernel/printk?
>

I use default values on RHEL5:

6 4 1 7

I don't think this is related with loglevel, what I checked
is dmesg, not just the console screen.

Thanks.
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From: David Miller on 27 Apr 2010 18:30
From: Amerigo Wang <amwang(a)redhat.com>
Date: Tue, 27 Apr 2010 03:56:09 -0400

> + if ((slave->dev->priv_flags & IFF_DISABLE_NETPOLL)
> + || !slave->dev->netdev_ops->ndo_poll_controller)

"|| on first line please, plus fix second line's indentation as per
comments given in patch #1 and #2
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From: Cong Wang on 27 Apr 2010 22:10
David Miller wrote:
> From: Amerigo Wang <amwang(a)redhat.com>
> Date: Tue, 27 Apr 2010 03:56:09 -0400
>
>> + if ((slave->dev->priv_flags & IFF_DISABLE_NETPOLL)
>> + || !slave->dev->netdev_ops->ndo_poll_controller)
>
> "|| on first line please, plus fix second line's indentation as per
> comments given in patch #1 and #2

Thanks, David!
I will fix all of this style problem.

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