Linux-libre 4.6.2-gnu

1 files changed, 24 insertions, 12 deletions

diff --git a/mm/mempool.c b/mm/mempool.c
index 7924f4f58..9b7a14a79 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -112,12 +112,12 @@ static void kasan_poison_element(mempool_t *pool, void *element)
 		kasan_free_pages(element, (unsigned long)pool->pool_data);
 }
 
-static void kasan_unpoison_element(mempool_t *pool, void *element)
+static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
 {
 	if (pool->alloc == mempool_alloc_slab)
-		kasan_slab_alloc(pool->pool_data, element);
+		kasan_slab_alloc(pool->pool_data, element, flags);
 	if (pool->alloc == mempool_kmalloc)
-		kasan_krealloc(element, (size_t)pool->pool_data);
+		kasan_krealloc(element, (size_t)pool->pool_data, flags);
 	if (pool->alloc == mempool_alloc_pages)
 		kasan_alloc_pages(element, (unsigned long)pool->pool_data);
 }
@@ -130,12 +130,12 @@ static void add_element(mempool_t *pool, void *element)
 	pool->elements[pool->curr_nr++] = element;
 }
 
-static void *remove_element(mempool_t *pool)
+static void *remove_element(mempool_t *pool, gfp_t flags)
 {
 	void *element = pool->elements[--pool->curr_nr];
 
 	BUG_ON(pool->curr_nr < 0);
-	kasan_unpoison_element(pool, element);
+	kasan_unpoison_element(pool, element, flags);
 	check_element(pool, element);
 	return element;
 }
@@ -154,7 +154,7 @@ void mempool_destroy(mempool_t *pool)
 		return;
 
 	while (pool->curr_nr) {
-		void *element = remove_element(pool);
+		void *element = remove_element(pool, GFP_KERNEL);
 		pool->free(element, pool->pool_data);
 	}
 	kfree(pool->elements);
@@ -250,7 +250,7 @@ int mempool_resize(mempool_t *pool, int new_min_nr)
 	spin_lock_irqsave(&pool->lock, flags);
 	if (new_min_nr <= pool->min_nr) {
 		while (new_min_nr < pool->curr_nr) {
-			element = remove_element(pool);
+			element = remove_element(pool, GFP_KERNEL);
 			spin_unlock_irqrestore(&pool->lock, flags);
 			pool->free(element, pool->pool_data);
 			spin_lock_irqsave(&pool->lock, flags);
@@ -310,25 +310,36 @@ EXPORT_SYMBOL(mempool_resize);
  * returns NULL. Note that due to preallocation, this function
  * *never* fails when called from process contexts. (it might
  * fail if called from an IRQ context.)
- * Note: using __GFP_ZERO is not supported.
+ * Note: neither __GFP_NOMEMALLOC nor __GFP_ZERO are supported.
  */
-void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
+void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
 {
 	void *element;
 	unsigned long flags;
 	wait_queue_t wait;
 	gfp_t gfp_temp;
 
+	/* If oom killed, memory reserves are essential to prevent livelock */
+	VM_WARN_ON_ONCE(gfp_mask & __GFP_NOMEMALLOC);
+	/* No element size to zero on allocation */
 	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
+
 	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
 
-	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */
 	gfp_mask |= __GFP_NORETRY;	/* don't loop in __alloc_pages */
 	gfp_mask |= __GFP_NOWARN;	/* failures are OK */
 
 	gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
 
 repeat_alloc:
+	if (likely(pool->curr_nr)) {
+		/*
+		 * Don't allocate from emergency reserves if there are
+		 * elements available.  This check is racy, but it will
+		 * be rechecked each loop.
+		 */
+		gfp_temp |= __GFP_NOMEMALLOC;
+	}
 
 	element = pool->alloc(gfp_temp, pool->pool_data);
 	if (likely(element != NULL))
@@ -336,7 +347,7 @@ repeat_alloc:
 
 	spin_lock_irqsave(&pool->lock, flags);
 	if (likely(pool->curr_nr)) {
-		element = remove_element(pool);
+		element = remove_element(pool, gfp_temp);
 		spin_unlock_irqrestore(&pool->lock, flags);
 		/* paired with rmb in mempool_free(), read comment there */
 		smp_wmb();
@@ -352,11 +363,12 @@ repeat_alloc:
 	 * We use gfp mask w/o direct reclaim or IO for the first round.  If
 	 * alloc failed with that and @pool was empty, retry immediately.
 	 */
-	if (gfp_temp != gfp_mask) {
+	if ((gfp_temp & ~__GFP_NOMEMALLOC) != gfp_mask) {
 		spin_unlock_irqrestore(&pool->lock, flags);
 		gfp_temp = gfp_mask;
 		goto repeat_alloc;
 	}
+	gfp_temp = gfp_mask;
 
 	/* We must not sleep if !__GFP_DIRECT_RECLAIM */
 	if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {