On 13/01/17 15:41, Juergen Gross wrote:
> On 12/01/17 10:21, Chris Wilson wrote:
>> On Thu, Jan 12, 2017 at 07:03:25AM +0100, Juergen Gross wrote:
>>> On 11/01/17 18:08, Chris Wilson wrote:
>>>> On Wed, Jan 11, 2017 at 05:33:34PM +0100, Juergen Gross wrote:
>>>>> With kernel 4.10rc3 running as Xen dm0 I get at each boot:
>>>>>
>>>>> [ 49.213697] [drm] GPU HANG: ecode 7:0:0x3d1d3d3d, in gnome-shell
>>>>> [1431], reason: Hang on render ring, action: reset
>>>>> [ 49.213699] [drm] GPU hangs can indicate a bug anywhere in the entire
>>>>> gfx stack, including userspace.
>>>>> [ 49.213700] [drm] Please file a _new_ bug report on
>>>>> bugs.freedesktop.org against DRI -> DRM/Intel
>>>>> [ 49.213700] [drm] drm/i915 developers can then reassign to the right
>>>>> component if it's not a kernel issue.
>>>>> [ 49.213700] [drm] The gpu crash dump is required to analyze gpu
>>>>> hangs, so please always attach it.
>>>>> [ 49.213701] [drm] GPU crash dump saved to /sys/class/drm/card0/error
>>>>> [ 49.213755] drm/i915: Resetting chip after gpu hang
>>>>> [ 60.213769] drm/i915: Resetting chip after gpu hang
>>>>> [ 71.189737] drm/i915: Resetting chip after gpu hang
>>>>> [ 82.165747] drm/i915: Resetting chip after gpu hang
>>>>> [ 93.205727] drm/i915: Resetting chip after gpu hang
>>>>>
>>>>> The dump is attached.
>>>>
>>>> That's a nasty one. The first couple of pages of the batchbuffer appear
>>>> to be overwritten. (Full of 0xc2c2c2c2, i.e. probably pixel data.) That
>>>> may be a concurrent write by either the GPU or CPU, or we may have
>>>> incorrected mapped a set of pages. That it doesn't recovered suggests
>>>> that the corruption occurs frequently, probably on every request/batch.
>>>
>>> I hoped someone would have an idea already.
>>
>> Sorry, first report of something like this in a long time (that I can
>> remember at least). And the problem is that it can be anything from a
>> coherency to a concurrency issue, so no one patch springs to mind.
>> Thankfully it appears to be kernel related.
>> -Chris
>>
>
> Bisecting took longer than I thought, but I had to cherry pick some
> patches and rebase one of them multiple times...
>
> Finally I found the commit to blame: 920cf4194954ec ("drm/i915:
> Introduce an internal allocator for disposable private objects")
>
> In case you need me to produce some more data or test a patch
> feel free to reach out.
Anything new for this severe regression?
Without a fix 4.10 will be unusable with Xen on a machine with i915
graphics!
Juergen
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