1 files changed, 30 insertions, 98 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
index edd21d14e64f..f2418a1cfe68 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -16,40 +16,6 @@
 
 #include "i915_trace.h"
 
-static bool shrinker_lock(struct drm_i915_private *i915,
-			  unsigned int flags,
-			  bool *unlock)
-{
-	struct mutex *m = &i915->drm.struct_mutex;
-
-	switch (mutex_trylock_recursive(m)) {
-	case MUTEX_TRYLOCK_RECURSIVE:
-		*unlock = false;
-		return true;
-
-	case MUTEX_TRYLOCK_FAILED:
-		*unlock = false;
-		if (flags & I915_SHRINK_ACTIVE &&
-		    mutex_lock_killable_nested(m, I915_MM_SHRINKER) == 0)
-			*unlock = true;
-		return *unlock;
-
-	case MUTEX_TRYLOCK_SUCCESS:
-		*unlock = true;
-		return true;
-	}
-
-	BUG();
-}
-
-static void shrinker_unlock(struct drm_i915_private *i915, bool unlock)
-{
-	if (!unlock)
-		return;
-
-	mutex_unlock(&i915->drm.struct_mutex);
-}
-
 static bool swap_available(void)
 {
 	return get_nr_swap_pages() > 0;
@@ -61,7 +27,8 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
 	if (!i915_gem_object_is_shrinkable(obj))
 		return false;
 
-	/* Only report true if by unbinding the object and putting its pages
+	/*
+	 * Only report true if by unbinding the object and putting its pages
 	 * we can actually make forward progress towards freeing physical
 	 * pages.
 	 *
@@ -72,16 +39,8 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
 	if (atomic_read(&obj->mm.pages_pin_count) > atomic_read(&obj->bind_count))
 		return false;
 
-	/* If any vma are "permanently" pinned, it will prevent us from
-	 * reclaiming the obj->mm.pages. We only allow scanout objects to claim
-	 * a permanent pin, along with a few others like the context objects.
-	 * To simplify the scan, and to avoid walking the list of vma under the
-	 * object, we just check the count of its permanently pinned.
-	 */
-	if (READ_ONCE(obj->pin_global))
-		return false;
-
-	/* We can only return physical pages to the system if we can either
+	/*
+	 * We can only return physical pages to the system if we can either
 	 * discard the contents (because the user has marked them as being
 	 * purgeable) or if we can move their contents out to swap.
 	 */
@@ -162,10 +121,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
 	intel_wakeref_t wakeref = 0;
 	unsigned long count = 0;
 	unsigned long scanned = 0;
-	bool unlock;
-
-	if (!shrinker_lock(i915, shrink, &unlock))
-		return 0;
 
 	/*
 	 * When shrinking the active list, we should also consider active
@@ -275,8 +230,6 @@ i915_gem_shrink(struct drm_i915_private *i915,
 	if (shrink & I915_SHRINK_BOUND)
 		intel_runtime_pm_put(&i915->runtime_pm, wakeref);
 
-	shrinker_unlock(i915, unlock);
-
 	if (nr_scanned)
 		*nr_scanned += scanned;
 	return count;
@@ -346,19 +299,14 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 	struct drm_i915_private *i915 =
 		container_of(shrinker, struct drm_i915_private, mm.shrinker);
 	unsigned long freed;
-	bool unlock;
 
 	sc->nr_scanned = 0;
 
-	if (!shrinker_lock(i915, 0, &unlock))
-		return SHRINK_STOP;
-
 	freed = i915_gem_shrink(i915,
 				sc->nr_to_scan,
 				&sc->nr_scanned,
 				I915_SHRINK_BOUND |
-				I915_SHRINK_UNBOUND |
-				I915_SHRINK_WRITEBACK);
+				I915_SHRINK_UNBOUND);
 	if (sc->nr_scanned < sc->nr_to_scan && current_is_kswapd()) {
 		intel_wakeref_t wakeref;
 
@@ -373,8 +321,6 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 		}
 	}
 
-	shrinker_unlock(i915, unlock);
-
 	return sc->nr_scanned ? freed : SHRINK_STOP;
 }
 
@@ -391,6 +337,7 @@ i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 	freed_pages = 0;
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
 		freed_pages += i915_gem_shrink(i915, -1UL, NULL,
+					       I915_SHRINK_ACTIVE |
 					       I915_SHRINK_BOUND |
 					       I915_SHRINK_UNBOUND |
 					       I915_SHRINK_WRITEBACK);
@@ -426,10 +373,6 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 	struct i915_vma *vma, *next;
 	unsigned long freed_pages = 0;
 	intel_wakeref_t wakeref;
-	bool unlock;
-
-	if (!shrinker_lock(i915, 0, &unlock))
-		return NOTIFY_DONE;
 
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
 		freed_pages += i915_gem_shrink(i915, -1UL, NULL,
@@ -446,15 +389,11 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 		if (!vma->iomap || i915_vma_is_active(vma))
 			continue;
 
-		mutex_unlock(&i915->ggtt.vm.mutex);
-		if (i915_vma_unbind(vma) == 0)
+		if (__i915_vma_unbind(vma) == 0)
 			freed_pages += count;
-		mutex_lock(&i915->ggtt.vm.mutex);
 	}
 	mutex_unlock(&i915->ggtt.vm.mutex);
 
-	shrinker_unlock(i915, unlock);
-
 	*(unsigned long *)ptr += freed_pages;
 	return NOTIFY_DONE;
 }
@@ -497,72 +436,65 @@ void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
 
 	fs_reclaim_acquire(GFP_KERNEL);
 
-	/*
-	 * As we invariably rely on the struct_mutex within the shrinker,
-	 * but have a complicated recursion dance, taint all the mutexes used
-	 * within the shrinker with the struct_mutex. For completeness, we
-	 * taint with all subclass of struct_mutex, even though we should
-	 * only need tainting by I915_MM_NORMAL to catch possible ABBA
-	 * deadlocks from using struct_mutex inside @mutex.
-	 */
-	mutex_acquire(&i915->drm.struct_mutex.dep_map,
-		      I915_MM_SHRINKER, 0, _RET_IP_);
-
 	mutex_acquire(&mutex->dep_map, 0, 0, _RET_IP_);
-	mutex_release(&mutex->dep_map, 0, _RET_IP_);
-
-	mutex_release(&i915->drm.struct_mutex.dep_map, 0, _RET_IP_);
+	mutex_release(&mutex->dep_map, _RET_IP_);
 
 	fs_reclaim_release(GFP_KERNEL);
 
 	if (unlock)
-		mutex_release(&i915->drm.struct_mutex.dep_map, 0, _RET_IP_);
+		mutex_release(&i915->drm.struct_mutex.dep_map, _RET_IP_);
 }
 
 #define obj_to_i915(obj__) to_i915((obj__)->base.dev)
 
 void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj)
 {
+	struct drm_i915_private *i915 = obj_to_i915(obj);
+	unsigned long flags;
+
 	/*
 	 * We can only be called while the pages are pinned or when
 	 * the pages are released. If pinned, we should only be called
 	 * from a single caller under controlled conditions; and on release
 	 * only one caller may release us. Neither the two may cross.
 	 */
-	if (!list_empty(&obj->mm.link)) { /* pinned by caller */
-		struct drm_i915_private *i915 = obj_to_i915(obj);
-		unsigned long flags;
-
-		spin_lock_irqsave(&i915->mm.obj_lock, flags);
-		GEM_BUG_ON(list_empty(&obj->mm.link));
+	if (atomic_add_unless(&obj->mm.shrink_pin, 1, 0))
+		return;
 
+	spin_lock_irqsave(&i915->mm.obj_lock, flags);
+	if (!atomic_fetch_inc(&obj->mm.shrink_pin) &&
+	    !list_empty(&obj->mm.link)) {
 		list_del_init(&obj->mm.link);
 		i915->mm.shrink_count--;
 		i915->mm.shrink_memory -= obj->base.size;
-
-		spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 	}
+	spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 }
 
 static void __i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj,
 					      struct list_head *head)
 {
+	struct drm_i915_private *i915 = obj_to_i915(obj);
+	unsigned long flags;
+
 	GEM_BUG_ON(!i915_gem_object_has_pages(obj));
-	GEM_BUG_ON(!list_empty(&obj->mm.link));
+	if (!i915_gem_object_is_shrinkable(obj))
+		return;
 
-	if (i915_gem_object_is_shrinkable(obj)) {
-		struct drm_i915_private *i915 = obj_to_i915(obj);
-		unsigned long flags;
+	if (atomic_add_unless(&obj->mm.shrink_pin, -1, 1))
+		return;
 
-		spin_lock_irqsave(&i915->mm.obj_lock, flags);
-		GEM_BUG_ON(!kref_read(&obj->base.refcount));
+	spin_lock_irqsave(&i915->mm.obj_lock, flags);
+	GEM_BUG_ON(!kref_read(&obj->base.refcount));
+	if (atomic_dec_and_test(&obj->mm.shrink_pin)) {
+		GEM_BUG_ON(!list_empty(&obj->mm.link));
 
 		list_add_tail(&obj->mm.link, head);
 		i915->mm.shrink_count++;
 		i915->mm.shrink_memory += obj->base.size;
 
-		spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 	}
+	spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 }
 
 void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj)