[PATCH] drm/i915: Flush pending GTT writes before unbinding

* [PATCH] drm/i915: Flush pending GTT writes before unbinding
@ 2017-12-04 12:43 Chris Wilson
  2017-12-04 12:46   ` Joonas Lahtinen
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: Chris Wilson @ 2017-12-04 12:43 UTC (permalink / raw)
  To: intel-gfx; +Cc: Chris Wilson, Joonas Lahtinen, stable

>From the shrinker paths, we want to relinquish the GPU and GGTT access to
the object, releasing the backing storage back to the system for
swapout. As a part of that process we would unpin the pages, marking
them for access by the CPU (for the swapout/swapin). However, if that
process was interrupted after unbind the vma, we missed a flush of the
inflight GGTT writes before we made that GTT space available again for
reuse, with the prospect that we would redirect them to another page.

The bug dates back to the introduction of multiple GGTT vma, but the
code itself dates to commit 02bef8f98d26 ("drm/i915: Unbind closed vma
for i915_gem_object_unbind()").

Fixes: 02bef8f98d26 ("drm/i915: Unbind closed vma for i915_gem_object_unbind()")
Fixes: c5ad54cf7dd8 ("drm/i915: Use partial view in mmap fault handler")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/i915/i915_gem.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e083f242b8dc..80b78fb5daac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -330,17 +330,10 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj)
 	 * must wait for all rendering to complete to the object (as unbinding
 	 * must anyway), and retire the requests.
 	 */
-	ret = i915_gem_object_wait(obj,
-				   I915_WAIT_INTERRUPTIBLE |
-				   I915_WAIT_LOCKED |
-				   I915_WAIT_ALL,
-				   MAX_SCHEDULE_TIMEOUT,
-				   NULL);
+	ret = i915_gem_object_set_to_cpu_domain(obj, false);
 	if (ret)
 		return ret;
 
-	i915_gem_retire_requests(to_i915(obj->base.dev));
-
 	while ((vma = list_first_entry_or_null(&obj->vma_list,
 					       struct i915_vma,
 					       obj_link))) {
-- 
2.15.1

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