[PATCH] i915: slab shrinker have to return -1 if it can't shrink any objects

[KOSAKI Motohiro]

Now, i915_gem_inactive_shrink() should return -1 instead of 0 if it
can't take a lock. Otherwise, vmscan is getting a lot of confusing
because vmscan can't distinguish "can't take a lock temporary" and
"we've shrank all of i915 objects".

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro at jp.fujitsu.com>
Cc: Keith Packard <keithp at keithp.com>
Cc: David Airlie <airlied at linux.ie>
Cc: dri-devel at lists.freedesktop.org
---

I've found this issue by reviewing. I hope i915 developers confirm this.
Thx.


 drivers/gpu/drm/i915/i915_gem.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 94c84d7..2f9a9b2 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4104,7 +4104,7 @@ i915_gem_inactive_shrink(struct shrinker *shrinker, struct shrink_control *sc)
 	int cnt;

 	if (!mutex_trylock(&dev->struct_mutex))
-		return 0;
+		return nr_to_scan ? -1 : 0;

 	/* "fast-path" to count number of available objects */
 	if (nr_to_scan == 0) {
-- 
1.7.3.1