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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2014-08-03 20:02:03 +0900 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-09-13 23:41:43 +0100 |
| commit | 312b559d9e61b473b39d3dc05fe0db43c2df60fb (patch) | |
| tree | 6855c1414c49f8e026b8385bc88d007d04d3fb2f /drivers/gpu | |
| parent | 0d362ea03048606016efe050bdcc46ff87ae4506 (diff) | |
| download | kernel_samsung_smdk4412-312b559d9e61b473b39d3dc05fe0db43c2df60fb.zip kernel_samsung_smdk4412-312b559d9e61b473b39d3dc05fe0db43c2df60fb.tar.gz kernel_samsung_smdk4412-312b559d9e61b473b39d3dc05fe0db43c2df60fb.tar.bz2 | |
drm/ttm: Fix possible stack overflow by recursive shrinker calls.
commit 71336e011d1d2312bcbcaa8fcec7365024f3a95d upstream.
While ttm_dma_pool_shrink_scan() tries to take mutex before doing GFP_KERNEL
allocation, ttm_pool_shrink_scan() does not do it. This can result in stack
overflow if kmalloc() in ttm_page_pool_free() triggered recursion due to
memory pressure.
shrink_slab()
=> ttm_pool_shrink_scan()
=> ttm_page_pool_free()
=> kmalloc(GFP_KERNEL)
=> shrink_slab()
=> ttm_pool_shrink_scan()
=> ttm_page_pool_free()
=> kmalloc(GFP_KERNEL)
Change ttm_pool_shrink_scan() to do like ttm_dma_pool_shrink_scan() does.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Airlie <airlied@redhat.com>
[bwh: Backported to 3.2:
- Adjust context
- Change return value in the contended case to follow the old shrinker
API]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_page_alloc.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c index 9e4313e..508c64c 100644 --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c @@ -398,13 +398,18 @@ static int ttm_pool_get_num_unused_pages(void) static int ttm_pool_mm_shrink(struct shrinker *shrink, struct shrink_control *sc) { - static atomic_t start_pool = ATOMIC_INIT(0); + static DEFINE_MUTEX(lock); + static unsigned start_pool; unsigned i; - unsigned pool_offset = atomic_add_return(1, &start_pool); + unsigned pool_offset; struct ttm_page_pool *pool; int shrink_pages = sc->nr_to_scan; - pool_offset = pool_offset % NUM_POOLS; + if (shrink_pages == 0) + goto out; + if (!mutex_trylock(&lock)) + return -1; + pool_offset = ++start_pool % NUM_POOLS; /* select start pool in round robin fashion */ for (i = 0; i < NUM_POOLS; ++i) { unsigned nr_free = shrink_pages; @@ -413,6 +418,8 @@ static int ttm_pool_mm_shrink(struct shrinker *shrink, pool = &_manager->pools[(i + pool_offset)%NUM_POOLS]; shrink_pages = ttm_page_pool_free(pool, nr_free); } + mutex_unlock(&lock); +out: /* return estimated number of unused pages in pool */ return ttm_pool_get_num_unused_pages(); } |