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drm/ttm: Pass GFP flags in order to avoid deadlock.
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Commit 7dc19d5 "drivers: convert shrinkers to new count/scan API" added
deadlock warnings that ttm_page_pool_free() and ttm_dma_page_pool_free()
are currently doing GFP_KERNEL allocation.

But these functions did not get updated to receive gfp_t argument.
This patch explicitly passes sc->gfp_mask or GFP_KERNEL to these functions,
and removes the deadlock warning.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@kernel.org> [2.6.35+]
Signed-off-by: Dave Airlie <airlied@redhat.com>
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Tetsuo Handa authored and Dave Airlie committed Aug 5, 2014
1 parent 71336e0 commit a91576d
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Showing 2 changed files with 19 additions and 19 deletions.
19 changes: 10 additions & 9 deletions drivers/gpu/drm/ttm/ttm_page_alloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -297,8 +297,10 @@ static void ttm_pool_update_free_locked(struct ttm_page_pool *pool,
*
* @pool: to free the pages from
* @free_all: If set to true will free all pages in pool
* @gfp: GFP flags.
**/
static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free)
static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free,
gfp_t gfp)
{
unsigned long irq_flags;
struct page *p;
Expand All @@ -309,8 +311,7 @@ static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free)
if (NUM_PAGES_TO_ALLOC < nr_free)
npages_to_free = NUM_PAGES_TO_ALLOC;

pages_to_free = kmalloc(npages_to_free * sizeof(struct page *),
GFP_KERNEL);
pages_to_free = kmalloc(npages_to_free * sizeof(struct page *), gfp);
if (!pages_to_free) {
pr_err("Failed to allocate memory for pool free operation\n");
return 0;
Expand Down Expand Up @@ -382,9 +383,7 @@ static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free)
*
* XXX: (dchinner) Deadlock warning!
*
* ttm_page_pool_free() does memory allocation using GFP_KERNEL. that means
* this can deadlock when called a sc->gfp_mask that is not equal to
* GFP_KERNEL.
* We need to pass sc->gfp_mask to ttm_page_pool_free().
*
* This code is crying out for a shrinker per pool....
*/
Expand All @@ -408,7 +407,8 @@ ttm_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
if (shrink_pages == 0)
break;
pool = &_manager->pools[(i + pool_offset)%NUM_POOLS];
shrink_pages = ttm_page_pool_free(pool, nr_free);
shrink_pages = ttm_page_pool_free(pool, nr_free,
sc->gfp_mask);
freed += nr_free - shrink_pages;
}
mutex_unlock(&lock);
Expand Down Expand Up @@ -710,7 +710,7 @@ static void ttm_put_pages(struct page **pages, unsigned npages, int flags,
}
spin_unlock_irqrestore(&pool->lock, irq_flags);
if (npages)
ttm_page_pool_free(pool, npages);
ttm_page_pool_free(pool, npages, GFP_KERNEL);
}

/*
Expand Down Expand Up @@ -850,7 +850,8 @@ void ttm_page_alloc_fini(void)
ttm_pool_mm_shrink_fini(_manager);

for (i = 0; i < NUM_POOLS; ++i)
ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES);
ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES,
GFP_KERNEL);

kobject_put(&_manager->kobj);
_manager = NULL;
Expand Down
19 changes: 9 additions & 10 deletions drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -411,8 +411,10 @@ static void ttm_dma_page_put(struct dma_pool *pool, struct dma_page *d_page)
*
* @pool: to free the pages from
* @nr_free: If set to true will free all pages in pool
* @gfp: GFP flags.
**/
static unsigned ttm_dma_page_pool_free(struct dma_pool *pool, unsigned nr_free)
static unsigned ttm_dma_page_pool_free(struct dma_pool *pool, unsigned nr_free,
gfp_t gfp)
{
unsigned long irq_flags;
struct dma_page *dma_p, *tmp;
Expand All @@ -430,8 +432,7 @@ static unsigned ttm_dma_page_pool_free(struct dma_pool *pool, unsigned nr_free)
npages_to_free, nr_free);
}
#endif
pages_to_free = kmalloc(npages_to_free * sizeof(struct page *),
GFP_KERNEL);
pages_to_free = kmalloc(npages_to_free * sizeof(struct page *), gfp);

if (!pages_to_free) {
pr_err("%s: Failed to allocate memory for pool free operation\n",
Expand Down Expand Up @@ -530,7 +531,7 @@ static void ttm_dma_free_pool(struct device *dev, enum pool_type type)
if (pool->type != type)
continue;
/* Takes a spinlock.. */
ttm_dma_page_pool_free(pool, FREE_ALL_PAGES);
ttm_dma_page_pool_free(pool, FREE_ALL_PAGES, GFP_KERNEL);
WARN_ON(((pool->npages_in_use + pool->npages_free) != 0));
/* This code path is called after _all_ references to the
* struct device has been dropped - so nobody should be
Expand Down Expand Up @@ -983,7 +984,7 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)

/* shrink pool if necessary (only on !is_cached pools)*/
if (npages)
ttm_dma_page_pool_free(pool, npages);
ttm_dma_page_pool_free(pool, npages, GFP_KERNEL);
ttm->state = tt_unpopulated;
}
EXPORT_SYMBOL_GPL(ttm_dma_unpopulate);
Expand All @@ -993,10 +994,7 @@ EXPORT_SYMBOL_GPL(ttm_dma_unpopulate);
*
* XXX: (dchinner) Deadlock warning!
*
* ttm_dma_page_pool_free() does GFP_KERNEL memory allocation, and so attention
* needs to be paid to sc->gfp_mask to determine if this can be done or not.
* GFP_KERNEL memory allocation in a GFP_ATOMIC reclaim context woul dbe really
* bad.
* We need to pass sc->gfp_mask to ttm_dma_page_pool_free().
*
* I'm getting sadder as I hear more pathetical whimpers about needing per-pool
* shrinkers
Expand Down Expand Up @@ -1030,7 +1028,8 @@ ttm_dma_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
if (++idx < pool_offset)
continue;
nr_free = shrink_pages;
shrink_pages = ttm_dma_page_pool_free(p->pool, nr_free);
shrink_pages = ttm_dma_page_pool_free(p->pool, nr_free,
sc->gfp_mask);
freed += nr_free - shrink_pages;

pr_debug("%s: (%s:%d) Asked to shrink %d, have %d more to go\n",
Expand Down

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