slub: Fallback to kmalloc_large for failing higher order allocs

[linux-2.6-omap-h63xx.git] / mm / slub.c

diff --git a/mm/slub.c b/mm/slub.c
index ccfd41141b6bd54b28cc412bfc7aa4583f869bd4..644fd0aaeaf1810b446bbbd74aac48ff9591ad03 100644 (file)
--- 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;