[dm-devel] v4.8 dm-mpath

[Bart Van Assche]

On 08/26/2016 07:26 AM, Mike Snitzer wrote:
> On Thu, Aug 25 2016 at  1:40pm -0400,
> Bart Van Assche <bart.vanassche at sandisk.com> wrote:
>> As usual, thanks for the quick feedback. But it seems like I sent my
>> e-mail too soon: after I had sent my e-mail I ran again into the
>> truncate_inode_pages_range() hang.
>
> I was skeptical your 3 earlier patches (particularly the __dm_destroy to
> use internel suspend patch) would fix anything you care about in your
> testing.  __dm_destroy is only used once all references on the DM mpath
> device are dropped.  When you do your fio + cable pull tests you're just
> bouncing underlying paths around.  You aren't _ever_ destroying the
> multipath device.  That is why your __dm_destroy patch seemed off the
> mark to me.

Hello Mike,

In case it wasn't clear, I want to drop the three patches you referred 
to. But I also want to clarify that my tests *do* trigger 
__dm_destroy(). If you have a look at the srp-test scripts then you will 
see that "dmsetup remove" is invoked after each test. What I see is that 
lock_page() and other page cache functions hang sporadically around the 
time the dm device is removed, most likely due to I/O that is submitted 
but never completed. That's why I started looking at the scsi-mq/blk-mq 
device removal code.

Bart.