1 files changed, 38 insertions, 5 deletions

diff --git a/mm/slub.c b/mm/slub.c
index ccfd41141b6b..644fd0aaeaf1 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -211,6 +211,8 @@ static inline void ClearSlabDebug(struct page *page)
 /* Internal SLUB flags */
 #define __OBJECT_POISON         0x80000000 /* Poison object */
 #define __SYSFS_ADD_DEFERRED    0x40000000 /* Not yet visible via sysfs */
+#define __KMALLOC_CACHE         0x20000000 /* objects freed using kfree */
+#define __PAGE_ALLOC_FALLBACK   0x10000000 /* Allow fallback to page alloc */
 
 /* Not all arches define cache_line_size */
 #ifndef cache_line_size
@@ -1539,7 +1541,6 @@ load_freelist:
 unlock_out:
         slab_unlock(c->page);
         stat(c, ALLOC_SLOWPATH);
-out:
 #ifdef SLUB_FASTPATH
         local_irq_restore(flags);
 #endif
@@ -1574,8 +1575,24 @@ new_slab:
                 c->page = new;
                 goto load_freelist;
         }
-        object = NULL;
-        goto out;
+#ifdef SLUB_FASTPATH
+        local_irq_restore(flags);
+#endif
+        /*
+         * No memory available.
+         *
+         * If the slab uses higher order allocs but the object is
+         * smaller than a page size then we can fallback in emergencies
+         * to the page allocator via kmalloc_large. The page allocator may
+         * have failed to obtain a higher order page and we can try to
+         * allocate a single page if the object fits into a single page.
+         * That is only possible if certain conditions are met that are being
+         * checked when a slab is created.
+         */
+        if (!(gfpflags & __GFP_NORETRY) && (s->flags & __PAGE_ALLOC_FALLBACK))
+                return kmalloc_large(s->objsize, gfpflags);
+
+        return NULL;
 debug:
         object = c->page->freelist;
         if (!alloc_debug_processing(s, c->page, object, addr))
@@ -2322,7 +2339,20 @@ static int calculate_sizes(struct kmem_cache *s)
         size = ALIGN(size, align);
         s->size = size;
 
-        s->order = calculate_order(size);
+        if ((flags & __KMALLOC_CACHE) &&
+                        PAGE_SIZE / size < slub_min_objects) {
+                /*
+                 * Kmalloc cache that would not have enough objects in
+                 * an order 0 page. Kmalloc slabs can fallback to
+                 * page allocator order 0 allocs so take a reasonably large
+                 * order that will allows us a good number of objects.
+                 */
+                s->order = max(slub_max_order, PAGE_ALLOC_COSTLY_ORDER);
+                s->flags |= __PAGE_ALLOC_FALLBACK;
+                s->allocflags |= __GFP_NOWARN;
+        } else
+                s->order = calculate_order(size);
+
         if (s->order < 0)
                 return 0;
 
@@ -2539,7 +2569,7 @@ static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
 
         down_write(&slub_lock);
         if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
-                        flags, NULL))
+                        flags | __KMALLOC_CACHE, NULL))
                 goto panic;
 
         list_add(&s->list, &slab_caches);
@@ -3058,6 +3088,9 @@ static int slab_unmergeable(struct kmem_cache *s)
         if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
                 return 1;
 
+        if ((s->flags & __PAGE_ALLOC_FALLBACK)
+                return 1;
+
         if (s->ctor)
                 return 1;