[Intel-gfx] [PATCH 3/4] drm/i915: Mark up vma->active as safe for use inside shrinkers

[Chris Wilson]

Since a shrinker may be forced to wait on GPU activity,
i915_active_wait(&vma->active) must be safe for use inside a shrinker,
and so let's mark up the lock as being acquired by the shrinker to avoid
any nasty surprises creeping in.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_vma.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index c20a3022cd80..ee73baf29415 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -22,6 +22,7 @@
  *
  */
 
+#include <linux/sched/mm.h>
 #include <drm/drm_gem.h>
 
 #include "display/intel_frontbuffer.h"
@@ -120,6 +121,13 @@ vma_create(struct drm_i915_gem_object *obj,
 			 __i915_vma_active, __i915_vma_retire);
 	INIT_ACTIVE_REQUEST(&vma->last_fence);
 
+	/* Declare ourselves safe for use inside shrinkers */
+	if (IS_ENABLED(CONFIG_LOCKDEP)) {
+		fs_reclaim_acquire(GFP_KERNEL);
+		might_lock(&vma->active.mutex);
+		fs_reclaim_release(GFP_KERNEL);
+	}
+
 	INIT_LIST_HEAD(&vma->closed_link);
 
 	if (view && view->type != I915_GGTT_VIEW_NORMAL) {
-- 
2.20.1