[PATCH] nommu: use compound page in slab allocator

The earlier patch to consolidate mmu and nommu page allocation and
refcounting by using compound pages for nommu allocations had a bug:
kmalloc slabs who's pages were initially allocated by a non-__GFP_COMP
allocator could be passed into mm/nommu.c kmalloc allocations which really
wanted __GFP_COMP underlying pages.  Fix that by having nommu pass
__GFP_COMP to all higher order slab allocations.

Signed-off-by: Luke Yang <luke.adi@gmail.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 752c5570f2f6..e6ef9bd52335 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1456,7 +1456,14 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
         int i;
 
         flags |= cachep->gfpflags;
+#ifndef CONFIG_MMU
+        /* nommu uses slab's for process anonymous memory allocations, so
+         * requires __GFP_COMP to properly refcount higher order allocations"
+         */
+        page = alloc_pages_node(nodeid, (flags | __GFP_COMP), cachep->gfporder);
+#else
         page = alloc_pages_node(nodeid, flags, cachep->gfporder);
+#endif
         if (!page)
                 return NULL;
         addr = page_address(page);