1 files changed, 16 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index d38413997379..f5efbb836e5c 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -293,15 +293,23 @@ i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj)
 static struct i915_mmu_notifier *
 i915_mmu_notifier_find(struct i915_mm_struct *mm)
 {
-        if (mm->mn == NULL) {
-                down_write(&mm->mm->mmap_sem);
-                mutex_lock(&to_i915(mm->dev)->mm_lock);
-                if (mm->mn == NULL)
-                        mm->mn = i915_mmu_notifier_create(mm->mm);
-                mutex_unlock(&to_i915(mm->dev)->mm_lock);
-                up_write(&mm->mm->mmap_sem);
+        struct i915_mmu_notifier *mn = mm->mn;
+
+        mn = mm->mn;
+        if (mn)
+                return mn;
+
+        down_write(&mm->mm->mmap_sem);
+        mutex_lock(&to_i915(mm->dev)->mm_lock);
+        if ((mn = mm->mn) == NULL) {
+                mn = i915_mmu_notifier_create(mm->mm);
+                if (!IS_ERR(mn))
+                        mm->mn = mn;
         }
-        return mm->mn;
+        mutex_unlock(&to_i915(mm->dev)->mm_lock);
+        up_write(&mm->mm->mmap_sem);
+
+        return mn;
 }
 
 static int