drm/i915/shrinker: Restrict vmap purge to objects with vmaps

When called because we have run out of vmap address space, we only need
to recover objects that have vmappings and not all.

v2: Start using is_vmalloc_addr()

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460113874-17366-5-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -3342,6 +3342,7 @@ unsigned long i915_gem_shrink(struct drm_i915_private *dev_priv,
 #define I915_SHRINK_UNBOUND 0x2
 #define I915_SHRINK_BOUND 0x4
 #define I915_SHRINK_ACTIVE 0x8
+#define I915_SHRINK_VMAPS 0x10
 unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv);
 void i915_gem_shrinker_init(struct drm_i915_private *dev_priv);
 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/i915_gem_shrinker.c

@@ -167,6 +167,10 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
 			    obj->madv != I915_MADV_DONTNEED)
 				continue;
 
+			if (flags & I915_SHRINK_VMAPS &&
+			    !is_vmalloc_addr(obj->mapping))
+				continue;
+
 			if ((flags & I915_SHRINK_ACTIVE) == 0 && obj->active)
 				continue;
 
@@ -388,7 +392,11 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 	if (!i915_gem_shrinker_lock_uninterruptible(dev_priv, &slu, 5000))
 		return NOTIFY_DONE;
 
-	freed_pages = i915_gem_shrink_all(dev_priv);
+	freed_pages = i915_gem_shrink(dev_priv, -1UL,
+				      I915_SHRINK_BOUND |
+				      I915_SHRINK_UNBOUND |
+				      I915_SHRINK_ACTIVE |
+				      I915_SHRINK_VMAPS);
 
 	i915_gem_shrinker_unlock_uninterruptible(dev_priv, &slu);