UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

drm/ttm: Use mutex_trylock() to avoid deadlock inside shrinker functions. 

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>
Cc: stable <stable@kernel.org> [3.3+]
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Tetsuo Handa 2014-08-03 20:01:10 +09:00 committed by Dave Airlie
parent 46c2df68f0
commit 22e71691fd
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
View File

@ -1014,7 +1014,8 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
if (list_empty(&_manager->pools)) if (list_empty(&_manager->pools))
return SHRINK_STOP; return SHRINK_STOP;
mutex_lock(&_manager->lock); if (!mutex_trylock(&_manager->lock))
return SHRINK_STOP;
if (!_manager->npools) if (!_manager->npools)
goto out; goto out;
pool_offset = ++start_pool % _manager->npools; pool_offset = ++start_pool % _manager->npools;
@ -1047,7 +1048,8 @@ ttm_dma_pool_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
struct device_pools *p; struct device_pools *p;
unsigned long count = 0; unsigned long count = 0;
mutex_lock(&_manager->lock); if (!mutex_trylock(&_manager->lock))
return 0;
list_for_each_entry(p, &_manager->pools, pools) list_for_each_entry(p, &_manager->pools, pools)
count += p->pool->npages_free; count += p->pool->npages_free;
mutex_unlock(&_manager->lock); mutex_unlock(&_manager->lock);