| Message ID | 201405311200.III57894.MLFOOFStQVHJFO@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, May 31, 2014 at 12:00:45PM +0900, Tetsuo Handa wrote: > >From 4e8d1a83629c5966bfd401c5f2187355624194f2 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Date: Sat, 31 May 2014 09:59:44 +0900 > Subject: [PATCH 3/5] gpu/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+] > --- > 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 d8e59f7..620da39 100644 > --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c > +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c > @@ -1014,7 +1014,8 @@ 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_lock(&_manager->lock)) > + return SHRINK_STOP; Hmm.. /home/konrad/linux/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c: In function ‘ttm_dma_pool_shrink_scan’: /home/konrad/linux/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c:1015:2: error: invalid use of void expression if (!mutex_lock(&_manager->lock)) This is based on v3.15 with these patches. > if (!_manager->npools) > goto out; > 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; > 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); > -- > 1.7.1
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c index d8e59f7..620da39 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c @@ -1014,7 +1014,8 @@ 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_lock(&_manager->lock)) + return SHRINK_STOP; if (!_manager->npools) goto out; 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; 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);