1 files changed, 174 insertions, 18 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 1fcf3ac94b6c..55d84a22ad96 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -124,6 +124,8 @@
 
 #include <trace/events/kmem.h>
 
+#include	"internal.h"
+
 /*
  * DEBUG	- 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
  *		  0 for faster, smaller code (especially in the critical paths).
@@ -152,6 +154,12 @@
 #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
 #endif
 
+/*
+ * true if a page was allocated from pfmemalloc reserves for network-based
+ * swap
+ */
+static bool pfmemalloc_active __read_mostly;
+
 /* Legal flag mask for kmem_cache_create(). */
 #if DEBUG
 # define CREATE_MASK	(SLAB_RED_ZONE | \
@@ -257,9 +265,30 @@ struct array_cache {
 			 * Must have this definition in here for the proper
 			 * alignment of array_cache. Also simplifies accessing
 			 * the entries.
+			 *
+			 * Entries should not be directly dereferenced as
+			 * entries belonging to slabs marked pfmemalloc will
+			 * have the lower bits set SLAB_OBJ_PFMEMALLOC
 			 */
 };
 
+#define SLAB_OBJ_PFMEMALLOC	1
+static inline bool is_obj_pfmemalloc(void *objp)
+{
+	return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC;
+}
+
+static inline void set_obj_pfmemalloc(void **objp)
+{
+	*objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC);
+	return;
+}
+
+static inline void clear_obj_pfmemalloc(void **objp)
+{
+	*objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC);
+}
+
 /*
  * bootstrap: The caches do not work without cpuarrays anymore, but the
  * cpuarrays are allocated from the generic caches...
@@ -900,6 +929,102 @@ static struct array_cache *alloc_arraycache(int node, int entries,
 	return nc;
 }
 
+static inline bool is_slab_pfmemalloc(struct slab *slabp)
+{
+	struct page *page = virt_to_page(slabp->s_mem);
+
+	return PageSlabPfmemalloc(page);
+}
+
+/* Clears pfmemalloc_active if no slabs have pfmalloc set */
+static void recheck_pfmemalloc_active(struct kmem_cache *cachep,
+						struct array_cache *ac)
+{
+	struct kmem_list3 *l3 = cachep->nodelists[numa_mem_id()];
+	struct slab *slabp;
+	unsigned long flags;
+
+	if (!pfmemalloc_active)
+		return;
+
+	spin_lock_irqsave(&l3->list_lock, flags);
+	list_for_each_entry(slabp, &l3->slabs_full, list)
+		if (is_slab_pfmemalloc(slabp))
+			goto out;
+
+	list_for_each_entry(slabp, &l3->slabs_partial, list)
+		if (is_slab_pfmemalloc(slabp))
+			goto out;
+
+	list_for_each_entry(slabp, &l3->slabs_free, list)
+		if (is_slab_pfmemalloc(slabp))
+			goto out;
+
+	pfmemalloc_active = false;
+out:
+	spin_unlock_irqrestore(&l3->list_lock, flags);
+}
+
+static void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
+						gfp_t flags, bool force_refill)
+{
+	int i;
+	void *objp = ac->entry[--ac->avail];
+
+	/* Ensure the caller is allowed to use objects from PFMEMALLOC slab */
+	if (unlikely(is_obj_pfmemalloc(objp))) {
+		struct kmem_list3 *l3;
+
+		if (gfp_pfmemalloc_allowed(flags)) {
+			clear_obj_pfmemalloc(&objp);
+			return objp;
+		}
+
+		/* The caller cannot use PFMEMALLOC objects, find another one */
+		for (i = 1; i < ac->avail; i++) {
+			/* If a !PFMEMALLOC object is found, swap them */
+			if (!is_obj_pfmemalloc(ac->entry[i])) {
+				objp = ac->entry[i];
+				ac->entry[i] = ac->entry[ac->avail];
+				ac->entry[ac->avail] = objp;
+				return objp;
+			}
+		}
+
+		/*
+		 * If there are empty slabs on the slabs_free list and we are
+		 * being forced to refill the cache, mark this one !pfmemalloc.
+		 */
+		l3 = cachep->nodelists[numa_mem_id()];
+		if (!list_empty(&l3->slabs_free) && force_refill) {
+			struct slab *slabp = virt_to_slab(objp);
+			ClearPageSlabPfmemalloc(virt_to_page(slabp->s_mem));
+			clear_obj_pfmemalloc(&objp);
+			recheck_pfmemalloc_active(cachep, ac);
+			return objp;
+		}
+
+		/* No !PFMEMALLOC objects available */
+		ac->avail++;
+		objp = NULL;
+	}
+
+	return objp;
+}
+
+static void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
+								void *objp)
+{
+	if (unlikely(pfmemalloc_active)) {
+		/* Some pfmemalloc slabs exist, check if this is one */
+		struct page *page = virt_to_page(objp);
+		if (PageSlabPfmemalloc(page))
+			set_obj_pfmemalloc(&objp);
+	}
+
+	ac->entry[ac->avail++] = objp;
+}
+
 /*
  * Transfer objects in one arraycache to another.
  * Locking must be handled by the caller.
@@ -1076,7 +1201,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 			STATS_INC_ACOVERFLOW(cachep);
 			__drain_alien_cache(cachep, alien, nodeid);
 		}
-		alien->entry[alien->avail++] = objp;
+		ac_put_obj(cachep, alien, objp);
 		spin_unlock(&alien->lock);
 	} else {
 		spin_lock(&(cachep->nodelists[nodeid])->list_lock);
@@ -1759,6 +1884,10 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 		return NULL;
 	}
 
+	/* Record if ALLOC_PFMEMALLOC was set when allocating the slab */
+	if (unlikely(page->pfmemalloc))
+		pfmemalloc_active = true;
+
 	nr_pages = (1 << cachep->gfporder);
 	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
 		add_zone_page_state(page_zone(page),
@@ -1766,9 +1895,13 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 	else
 		add_zone_page_state(page_zone(page),
 			NR_SLAB_UNRECLAIMABLE, nr_pages);
-	for (i = 0; i < nr_pages; i++)
+	for (i = 0; i < nr_pages; i++) {
 		__SetPageSlab(page + i);
 
+		if (page->pfmemalloc)
+			SetPageSlabPfmemalloc(page + i);
+	}
+
 	if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK)) {
 		kmemcheck_alloc_shadow(page, cachep->gfporder, flags, nodeid);
 
@@ -1800,6 +1933,7 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
 				NR_SLAB_UNRECLAIMABLE, nr_freed);
 	while (i--) {
 		BUG_ON(!PageSlab(page));
+		__ClearPageSlabPfmemalloc(page);
 		__ClearPageSlab(page);
 		page++;
 	}
@@ -3015,16 +3149,19 @@ bad:
 #define check_slabp(x,y) do { } while(0)
 #endif
 
-static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
+static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags,
+							bool force_refill)
 {
 	int batchcount;
 	struct kmem_list3 *l3;
 	struct array_cache *ac;
 	int node;
 
-retry:
 	check_irq_off();
 	node = numa_mem_id();
+	if (unlikely(force_refill))
+		goto force_grow;
+retry:
 	ac = cpu_cache_get(cachep);
 	batchcount = ac->batchcount;
 	if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
@@ -3074,8 +3211,8 @@ retry:
 			STATS_INC_ACTIVE(cachep);
 			STATS_SET_HIGH(cachep);
 
-			ac->entry[ac->avail++] = slab_get_obj(cachep, slabp,
-							    node);
+			ac_put_obj(cachep, ac, slab_get_obj(cachep, slabp,
+									node));
 		}
 		check_slabp(cachep, slabp);
 
@@ -3094,18 +3231,22 @@ alloc_done:
 
 	if (unlikely(!ac->avail)) {
 		int x;
+force_grow:
 		x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL);
 
 		/* cache_grow can reenable interrupts, then ac could change. */
 		ac = cpu_cache_get(cachep);
-		if (!x && ac->avail == 0)	/* no objects in sight? abort */
+
+		/* no objects in sight? abort */
+		if (!x && (ac->avail == 0 || force_refill))
 			return NULL;
 
 		if (!ac->avail)		/* objects refilled by interrupt? */
 			goto retry;
 	}
 	ac->touched = 1;
-	return ac->entry[--ac->avail];
+
+	return ac_get_obj(cachep, ac, flags, force_refill);
 }
 
 static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
@@ -3187,23 +3328,35 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
 	void *objp;
 	struct array_cache *ac;
+	bool force_refill = false;
 
 	check_irq_off();
 
 	ac = cpu_cache_get(cachep);
 	if (likely(ac->avail)) {
-		STATS_INC_ALLOCHIT(cachep);
 		ac->touched = 1;
-		objp = ac->entry[--ac->avail];
-	} else {
-		STATS_INC_ALLOCMISS(cachep);
-		objp = cache_alloc_refill(cachep, flags);
+		objp = ac_get_obj(cachep, ac, flags, false);
+
 		/*
-		 * the 'ac' may be updated by cache_alloc_refill(),
-		 * and kmemleak_erase() requires its correct value.
+		 * Allow for the possibility all avail objects are not allowed
+		 * by the current flags
 		 */
-		ac = cpu_cache_get(cachep);
+		if (objp) {
+			STATS_INC_ALLOCHIT(cachep);
+			goto out;
+		}
+		force_refill = true;
 	}
+
+	STATS_INC_ALLOCMISS(cachep);
+	objp = cache_alloc_refill(cachep, flags, force_refill);
+	/*
+	 * the 'ac' may be updated by cache_alloc_refill(),
+	 * and kmemleak_erase() requires its correct value.
+	 */
+	ac = cpu_cache_get(cachep);
+
+out:
 	/*
 	 * To avoid a false negative, if an object that is in one of the
 	 * per-CPU caches is leaked, we need to make sure kmemleak doesn't
@@ -3525,9 +3678,12 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects,
 	struct kmem_list3 *l3;
 
 	for (i = 0; i < nr_objects; i++) {
-		void *objp = objpp[i];
+		void *objp;
 		struct slab *slabp;
 
+		clear_obj_pfmemalloc(&objpp[i]);
+		objp = objpp[i];
+
 		slabp = virt_to_slab(objp);
 		l3 = cachep->nodelists[node];
 		list_del(&slabp->list);
@@ -3645,7 +3801,7 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp,
 		cache_flusharray(cachep, ac);
 	}
 
-	ac->entry[ac->avail++] = objp;
+	ac_put_obj(cachep, ac, objp);
 }
 
 /**