From 016a65a39170c3cdca09a6ac343ff4f124668b45 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 11 Jun 2015 08:06:08 +0100 Subject: [PATCH] drm/i915: Always reset vma->ggtt_view.pages cache on unbinding 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 Date: Wed Dec 10 17:27:58 2014 +0000 drm/i915: Infrastructure for supporting different GGTT views per object Tvrtko says, 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. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1227892 Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: Daniel Vetter Cc: Michel Thierry Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin [Jani: Added Tvrtko's explanation to commit message.] Signed-off-by: Jani Nikula --- 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 851b585..c3806c6 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3000,8 +3000,8 @@ 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); -- 2.7.4