Re: [dm-devel] [GIT PULL] Queue free fix (was Re: [PATCH] block: Free queue resources at blk_release_queue())

[Mike Snitzer <snitzer redhat com>]

On Mon, Dec 12 2011 at  7:39am -0500,
Heiko Carstens <heiko carstens de ibm com> wrote:

> On Tue, Nov 29, 2011 at 03:18:03PM -0500, Mike Snitzer wrote:
> > On Tue, Nov 29 2011 at  7:00am -0500,
> > Heiko Carstens <heiko carstens de ibm com> wrote:
> > > [ 4906.683654] Unable to handle kernel pointer dereference at virtual kernel address 6b6b6b6b6b6b6000
> > 
> > ...
> > 
> > > Gonzalo also tried 2.6.38.8 as suggested and ran into this one:
> > > 
> > > [  292.877936] ------------[ cut here ]------------
> > > [  292.877939] Kernel BUG at 6b6b6b6b6b6b6b6d [verbose debug info unavailable]
> > 
> > Again, more poison.
> > 
> > Seems this test is causing us to fall on our face no matter what.
> > Likely, best to leave this 2.6.38 blk_unplug crash to one side and
> > continue focusing on latest upstream.
> 
> Sorry again, for taking so long to come back. This time however with good news:
> 
> With 3.2.0-rc4.00255.g77a7300 we were unable to reproduce any I/O stall or
> user-after-free bugs even after nearly 3000 test iterations.

Great news, so with an eye towards getting these fixes upstream:

> The only patches on top we have are:
> 
> two patches from Hannes:
> http://www.spinics.net/lists/linux-scsi/msg55112.html

Has that scsi_lib.c patch been posted with a formal patch header?

James, I'm not clear on where I should be looking to see what you have
staged but not yet sent to Linus.  Does such a branch exist in your
scsi-misc-2.6 tree?

> http://www.spinics.net/lists/linux-scsi/msg55413.html

Jun'ichi and Hannes said that additional NULL pointer check is needed:
http://www.redhat.com/archives/dm-devel/2011-December/msg00022.html

Hannes said he'd re-post an updated patch (but hasn't yet).

Mike