[PATCH 3/3] drm/i915: Mark up i915_active as safe for use inside shrinkers

[Chris Wilson]

Since a shrinker may be forced to wait on GPU activity,
i915_active_wait() 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_active.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index a55a0a954d74..fa6220456ac3 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -203,6 +203,11 @@ void __i915_active_init(struct drm_i915_private *i915,
 	init_llist_head(&ref->barriers);
 	atomic_set(&ref->count, 0);
 	__mutex_init(&ref->mutex, "i915_active", key);
+
+	/* Declare ourselves safe for use inside shrinkers */
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_lock(&ref->mutex);
+	fs_reclaim_release(GFP_KERNEL);
 }
 
 int i915_active_ref(struct i915_active *ref,
-- 
2.20.1