[PATCH] drm: i915_gem_inactive_scan: insufficient nr_to_scan size

[PATCH] drm: i915_gem_inactive_scan: insufficient nr_to_scan size

[Artem Savkov]

nr_to_scan needs to be (unsigned) long, not int, otherwise we get negative
values on 32bit systems during shrink resulting in lots of messages like one
below.

[ 4078.989603] shrink_slab: i915_gem_inactive_scan+0x0/0xc0 negative objects to delete nr=-289580136

Introduced in "drivers: convert shrinkers to new count/scan API"
(383e4f4a4cdeb2dd552e90811089bcb4d41eb32e in linux-next.git)

Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4635354..b3b4891b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4649,7 +4649,7 @@ i915_gem_inactive_scan(struct shrinker *shrinker, struct shrink_control *sc)
 			     struct drm_i915_private,
 			     mm.inactive_shrinker);
 	struct drm_device *dev = dev_priv->dev;
-	int nr_to_scan = sc->nr_to_scan;
+	unsigned long nr_to_scan = sc->nr_to_scan;
 	unsigned long freed;
 	bool unlock = true;
 
-- 
1.8.3.3

Re: [PATCH] drm: i915_gem_inactive_scan: insufficient nr_to_scan size

[Artem Savkov]

On Tue, Jul 23, 2013 at 11:18:06PM +0400, Artem Savkov wrote:
> nr_to_scan needs to be (unsigned) long, not int, otherwise we get negative
> values on 32bit systems during shrink resulting in lots of messages like one
> below.
> 
> [ 4078.989603] shrink_slab: i915_gem_inactive_scan+0x0/0xc0 negative objects to delete nr=-289580136
> 
> Introduced in "drivers: convert shrinkers to new count/scan API"
> (383e4f4a4cdeb2dd552e90811089bcb4d41eb32e in linux-next.git)

Sorry, looks like my analysis was wrong, I can still see the issue with this
patch.

-- 
Regards,
Artem