[PATCH 3.13 149/187] drm/ttm: Pass GFP flags in order to avoid deadlock.

Kamal Mostafa
2014-09-15T22:16:26Z

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

commit a91576d7916f6cce76d30303e60e1ac47cf4a76d upstream.

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: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/gpu/drm/ttm/ttm_page_alloc.c | 19 ++++++++++---------
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 19 +++++++++----------
2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index deba59b..cf4bad2 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -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;
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index 524cc1a..ca65df1 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -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",
--
1.9.1