From 5774506f157a91400c587b85d1ce4de56f0d32f6 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 21 Nov 2012 13:04:04 +0000 Subject: [PATCH] drm/i915: Borrow our struct_mutex for the direct reclaim If we have hit oom whilst holding our struct_mutex, then currently we cannot reap our own GPU buffers which likely pin most of memory, making an outright OOM more likely. So if we are running in direct reclaim and already hold the mutex, attempt to free buffers knowing that the original function can not continue until we return. v2: Add a note explaining that the mutex may be stolen due to pre-emption, and that is bad. Signed-off-by: Chris Wilson Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 71b5129..b0016bb 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -4342,6 +4342,19 @@ void i915_gem_release(struct drm_device *dev, struct drm_file *file) spin_unlock(&file_priv->mm.lock); } +static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task) +{ + if (!mutex_is_locked(mutex)) + return false; + +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_MUTEXES) + return mutex->owner == task; +#else + /* Since UP may be pre-empted, we cannot assume that we own the lock */ + return false; +#endif +} + static int i915_gem_inactive_shrink(struct shrinker *shrinker, struct shrink_control *sc) { @@ -4352,10 +4365,15 @@ i915_gem_inactive_shrink(struct shrinker *shrinker, struct shrink_control *sc) struct drm_device *dev = dev_priv->dev; struct drm_i915_gem_object *obj; int nr_to_scan = sc->nr_to_scan; + bool unlock = true; int cnt; - if (!mutex_trylock(&dev->struct_mutex)) - return 0; + if (!mutex_trylock(&dev->struct_mutex)) { + if (!mutex_is_locked_by(&dev->struct_mutex, current)) + return 0; + + unlock = false; + } if (nr_to_scan) { nr_to_scan -= i915_gem_purge(dev_priv, nr_to_scan); @@ -4371,6 +4389,7 @@ i915_gem_inactive_shrink(struct shrinker *shrinker, struct shrink_control *sc) if (obj->pin_count == 0 && obj->pages_pin_count == 0) cnt += obj->base.size >> PAGE_SHIFT; - mutex_unlock(&dev->struct_mutex); + if (unlock) + mutex_unlock(&dev->struct_mutex); return cnt; } -- 2.7.4