[dm-devel] [PATCH] multipathd: check and cleanup zombie paths

[Chongyun Wu]

On 2018/3/22 3:56, Bart Van Assche wrote:
> On Wed, 2018-03-21 at 01:54 +0000, Chongyun Wu wrote:
>> Is there any special operation or conditions to reproduce the dead lock?
>>    I have use SCSI sysfs delete atrribute to remove stale devices in my
>> previous patch and test many times, but I haven't encountered any
>> deadlock problems.
> 
> Hello Chongyun,
> 
> In my tests I enabled the lock validator (CONFIG_LOCKDEP) in order not only
> to obtain detailed information about the cause of actual deadlocks but also
> to obtain information about potential deadlocks.
> 
> I'm not sure how to make it more likely to trigger this deadlock. But I think
> that you should be aware that some SCSI transports remove the SCSI host if a
> transport failure is detected and other SCSI transports don't remove the SCSI
> host upon a transport failure. I ran my tests with the SRP protocol and the
> SRP transport protocol removes the SCSI host if a transport failure persists
> long enough. Maybe triggering SCSI host removal often helps to trigger that
> deadlock.
> 
> Bart.
> 
> 
> 
Hi Bart,

Thanks, as you mentioned maybe we have different scsi transport so we 
haven't found deadlock so far. Hope your mentioned issue *Avoid that 
SCSI device removal through sysfs triggers a deadlock* can be resolved 
by root. We often encounter problems with device residual which cause 
some issues and want to find a safe and effective method to clean up it.

Regards,
Chongyun