Re: hpsa driver bug crack kernel down!

[Bjorn Helgaas <bhelgaas@google.com>]

[+cc Joerg, iommu list]

On Wed, Apr 9, 2014 at 6:19 PM, Davidlohr Bueso <davidlohr@hp.com> wrote:
> On Wed, 2014-04-09 at 16:50 -0700, James Bottomley wrote:
>> On Wed, 2014-04-09 at 16:40 -0700, Davidlohr Bueso wrote:
>> > On Wed, 2014-04-09 at 16:10 -0700, James Bottomley wrote:
>> > > On Wed, 2014-04-09 at 16:08 -0700, James Bottomley wrote:
>> > > > [+linux-scsi]
>> > > > On Wed, 2014-04-09 at 15:49 -0700, Davidlohr Bueso wrote:
>> > > > > On Wed, 2014-04-09 at 10:39 +0800, Baoquan He wrote:
>> > > > > > Hi,
>> > > > > >
>> > > > > > The kernel is 3.14.0+ which is pulled just now.
>> > > > >
>> > > > > Cc'ing more people.
>> > > > >
>> > > > > While the hpsa driver appears to be involved in some way, I'm sure if
>> > > > > this is a related issue, but as of today's pull I'm getting another
>> > > > > problem that causes my DL980 not to come up.
>> > > > >
>> > > > > *Massive* amounts of:
>> > > > >
>> > > > > DMAR:[fault reason 02] Present bit in context entry is clear
>> > > > > dmar: DRHD: handling fault status reg 602
>> > > > > dmar: DMAR:[DMA Read] Request device [02:00.0] fault addr 7f61e000
>> > > > >
>> > > > > Then:
>> > > > >
>> > > > > hpsa 0000:03:00.0: Controller lockup detected: 0xffff0000
>> > > > > ...
>> > > > > Workqueue: events hpsa_monitor_ctlr_worker [hpsa]
>> > > > > ...
>> > > > >
>> > > > > Screenshot of the actual LOCKUP:
>> > > > > http://stgolabs.net/hpsa-hard-lockup-3.14+.png
>> > > > >
>> > > > > While I haven't bisected, things worked fine until at least until commit
>> > > > > 39de65aa2c3e (April 2nd).
>> > > > >
>> > > > > Any ideas?
>> > > >
>> > > > Well, it's either a DMA remapping issue or a hpsa one.  Your assertion
>> > > > that everything worked fine until 39de65aa2c3e would tend to vindicate
>> > > > hpsa,
>> >
>> > Hmm here you mean DMA, right?
>>
>> No, it vindicates the hpsa changes ... they don't seem to be causing
>> problems until something goes wrong with dma remapping.
>>
>> > > because all the hpsa changes went in before that under
>> > > Missing crucial info:
>> > >
>> > > commit 1a0b6abaea78f73d9bc0a2f6df2d9e4c917cade1
>> > >
>> > > > Merge: 3e75c6d b2bff6c
>> > > > Author: Linus Torvalds <torvalds@linux-foundation.org>
>> > > > Date:   Tue Apr 1 18:49:04 2014 -0700
>> > > >
>> > > >     Merge tag 'scsi-misc' of
>> > > > git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
>> > > >
>> > > > can you revalidate that this commit works OK just to make sure?
>> >
>> > Ok so I don't see those DMA messages and system starts just fine. I'm
>> > thinking perhaps something broke after the IO mmu stuff in commit
>> > 3f583bc21977a608908b83d03ee2250426a5695c... could this be indirectly
>> > causing the CPU stalls and just blame hpsa in the path as a side effect?
>> >
>> > /me goes out to try the commit.
>>
>> That's my guess.  The DMAR messages are DMA remapping issues caused in
>> the IOMMU.  If I had to guess, I'd say the DMAR fault message is
>> indicating the IOMMU is calling for a mapping address before it can
>> satisfy the driver read request, which is causing the hang apparently in
>> the hpsa driver.
>>
>> I've added linux-pci to the cc; I think they deal with iommu issues on
>> x86.
>
> So that merge commit appears to be the culprit, I see both the DMA
> messages and the lockup blaming hpsa...

My understanding so far (please correct me if I'm wrong):

39de65aa2c3e OK ("Merge branch 'i2c/for-next'")
1a0b6abaea78 OK ("Merge tag 'scsi-misc'")
3f583bc21977 BAD ("Merge tag 'iommu-updates-v3.15'")