Avoid double memclear() in SLOB/SLUB

Both slob and slub react to __GFP_ZERO by clearing the allocation, which
means that passing the GFP_ZERO bit down to the page allocator is just
wasteful and pointless.
Acked-by: NMatt Mackall <mpm@selenic.com>
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/slob.c

@@ -330,7 +330,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
 
 	/* Not enough space: must allocate a new page */
 	if (!b) {
-		b = slob_new_page(gfp, 0, node);
+		b = slob_new_page(gfp & ~__GFP_ZERO, 0, node);
 		if (!b)
 			return 0;
 		sp = (struct slob_page *)virt_to_page(b);

mm/slub.c

@@ -1468,6 +1468,9 @@ static void *__slab_alloc(struct kmem_cache *s,
 	void **object;
 	struct page *new;
 
+	/* We handle __GFP_ZERO in the caller */
+	gfpflags &= ~__GFP_ZERO;
+
 	if (!c->page)
 		goto new_slab;