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Commit a91576d7 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Dave Airlie
Browse files

drm/ttm: Pass GFP flags in order to avoid deadlock. 



Commit 7dc19d5a "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: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@kernel.org> [2.6.35+]
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 71336e01

drivers/gpu/drm/ttm/ttm_page_alloc.c

+10 −9
Original line number Diff line number Diff line
@@ -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;
@@ -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;
@@ -382,9 +383,7 @@ out: 
 *

 * 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....

 */
@@ -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);
@@ -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);

}



/*
@@ -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;

drivers/gpu/drm/ttm/ttm_page_alloc_dma.c

+9 −10
Original line number Diff line number Diff line
@@ -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;
@@ -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",
@@ -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
@@ -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);
@@ -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
@@ -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",