| Message ID | 1434006368-26742-1-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/11/2015 08:06 AM, Chris Wilson wrote: > With the introduction of multiple views of an obj in the same vm, each > vma was taught to cache its copy of the pages (so that different views > could have different page arrangements). However, this missed decoupling > those vma->ggtt_view.pages when the vma released its reference on the > obj->pages. As we don't always free the vma, this leads to a possible > scenario (e.g. execbuffer interrupted by the shrinker) where the vma > points to a stale obj->pages, and explodes. > > Fixes regression from commit fe14d5f4e5468c5b80a24f1a64abcbe116143670 > Author: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Date: Wed Dec 10 17:27:58 2014 +0000 > > drm/i915: Infrastructure for supporting different GGTT views per object > > Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1227892 > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Michel Thierry <michel.thierry@intel.com> > Cc: stable@vger.kernel.org > --- > drivers/gpu/drm/i915/i915_gem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 9ae98b00ff56..377a6da31a1c 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -3214,8 +3214,8 @@ int i915_vma_unbind(struct i915_vma *vma) > } else if (vma->ggtt_view.pages) { > sg_free_table(vma->ggtt_view.pages); > kfree(vma->ggtt_view.pages); > - vma->ggtt_view.pages = NULL; > } > + vma->ggtt_view.pages = NULL; > } > > drm_mm_remove_node(&vma->node); Nasty, thanks for fixing this. Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> If someone else will be confused how this can happen, key is the reservation execbuffer path. That puts the VMA on the exec_list which prevents i915_vma_unbind and i915_gem_vma_destroy from fully destroying the VMA. So the VMA is left existing as an empty object in the list - unbound and disassociated with the backing store. Kind of a cached memory object. And then re-using it needs to clear the cached pages pointer which is fixed above. Regards, Tvrtko
On Thu, 11 Jun 2015, Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> wrote: > On 06/11/2015 08:06 AM, Chris Wilson wrote: >> With the introduction of multiple views of an obj in the same vm, each >> vma was taught to cache its copy of the pages (so that different views >> could have different page arrangements). However, this missed decoupling >> those vma->ggtt_view.pages when the vma released its reference on the >> obj->pages. As we don't always free the vma, this leads to a possible >> scenario (e.g. execbuffer interrupted by the shrinker) where the vma >> points to a stale obj->pages, and explodes. >> >> Fixes regression from commit fe14d5f4e5468c5b80a24f1a64abcbe116143670 >> Author: Tvrtko Ursulin <tvrtko.ursulin@intel.com> >> Date: Wed Dec 10 17:27:58 2014 +0000 >> >> drm/i915: Infrastructure for supporting different GGTT views per object >> >> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1227892 >> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> >> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> Cc: Michel Thierry <michel.thierry@intel.com> >> Cc: stable@vger.kernel.org >> --- >> drivers/gpu/drm/i915/i915_gem.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c >> index 9ae98b00ff56..377a6da31a1c 100644 >> --- a/drivers/gpu/drm/i915/i915_gem.c >> +++ b/drivers/gpu/drm/i915/i915_gem.c >> @@ -3214,8 +3214,8 @@ int i915_vma_unbind(struct i915_vma *vma) >> } else if (vma->ggtt_view.pages) { >> sg_free_table(vma->ggtt_view.pages); >> kfree(vma->ggtt_view.pages); >> - vma->ggtt_view.pages = NULL; >> } >> + vma->ggtt_view.pages = NULL; >> } >> >> drm_mm_remove_node(&vma->node); > > Nasty, thanks for fixing this. > > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> > > If someone else will be confused how this can happen, key is the > reservation execbuffer path. That puts the VMA on the exec_list which > prevents i915_vma_unbind and i915_gem_vma_destroy from fully destroying > the VMA. So the VMA is left existing as an empty object in the list - > unbound and disassociated with the backing store. Kind of a cached > memory object. And then re-using it needs to clear the cached pages > pointer which is fixed above. Pushed to drm-intel-fixes with the above text added to commit message. Thanks for the patch and review. BR, Jani. > > Regards, > > Tvrtko > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 9ae98b00ff56..377a6da31a1c 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3214,8 +3214,8 @@ int i915_vma_unbind(struct i915_vma *vma) } else if (vma->ggtt_view.pages) { sg_free_table(vma->ggtt_view.pages); kfree(vma->ggtt_view.pages); - vma->ggtt_view.pages = NULL; } + vma->ggtt_view.pages = NULL; } drm_mm_remove_node(&vma->node);
With the introduction of multiple views of an obj in the same vm, each vma was taught to cache its copy of the pages (so that different views could have different page arrangements). However, this missed decoupling those vma->ggtt_view.pages when the vma released its reference on the obj->pages. As we don't always free the vma, this leads to a possible scenario (e.g. execbuffer interrupted by the shrinker) where the vma points to a stale obj->pages, and explodes. Fixes regression from commit fe14d5f4e5468c5b80a24f1a64abcbe116143670 Author: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Date: Wed Dec 10 17:27:58 2014 +0000 drm/i915: Infrastructure for supporting different GGTT views per object Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1227892 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Michel Thierry <michel.thierry@intel.com> Cc: stable@vger.kernel.org --- drivers/gpu/drm/i915/i915_gem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)