diff options
| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2014-08-03 20:01:10 +0900 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-09-18 16:40:00 +0200 |
| commit | 7d042e59c04b88edff83aa2ec1d1bc81f94bfaf4 (patch) | |
| tree | 47f71175f2be5eea48e754b21decf02edf00c9a8 | |
| parent | 50ac045c45d41dad0c4b38a456dcc58a64c58244 (diff) | |
drm/ttm: Use mutex_trylock() to avoid deadlock inside shrinker functions.
commit 22e71691fd54c637800d10816bbeba9cf132d218 upstream.
I can observe that RHEL7 environment stalls with 100% CPU usage when a
certain type of memory pressure is given. While the shrinker functions
are called by shrink_slab() before the OOM killer is triggered, the stall
lasts for many minutes.
One of reasons of this stall is that
ttm_dma_pool_shrink_count()/ttm_dma_pool_shrink_scan() are called and
are blocked at mutex_lock(&_manager->lock). GFP_KERNEL allocation with
_manager->lock held causes someone (including kswapd) to deadlock when
these functions are called due to memory pressure. This patch changes
"mutex_lock();" to "if (!mutex_trylock()) return ...;" in order to
avoid deadlock.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c index 5d49274afd0e..629e344dad1e 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c @@ -1013,7 +1013,8 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) if (list_empty(&_manager->pools)) return SHRINK_STOP; - mutex_lock(&_manager->lock); + if (!mutex_trylock(&_manager->lock)) + return SHRINK_STOP; if (!_manager->npools) goto out; pool_offset = ++start_pool % _manager->npools; @@ -1046,7 +1047,8 @@ ttm_dma_pool_shrink_count(struct shrinker *shrink, struct shrink_control *sc) struct device_pools *p; unsigned long count = 0; - mutex_lock(&_manager->lock); + if (!mutex_trylock(&_manager->lock)) + return 0; list_for_each_entry(p, &_manager->pools, pools) count += p->pool->npages_free; mutex_unlock(&_manager->lock); |