summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--mm/slub.c43
1 files changed, 38 insertions, 5 deletions
diff --git a/mm/slub.c b/mm/slub.c
index ccfd411..644fd0a 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;
OpenPOWER on IntegriCloud