linux-kernel - [PATCH 1/2] slab: do ClearSlabPfmemalloc() for all pages of slab

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Date:	Sat, 25 Aug 2012 23:11:10 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <js1304@...il.com>, Mel Gorman <mgorman@...e.de>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: [PATCH 1/2] slab:  do ClearSlabPfmemalloc() for all pages of slab

Now, we just do ClearSlabPfmemalloc() for first page of slab
when we clear SlabPfmemalloc flag. It is a problem because we sometimes
test flag of page which is not first page of slab in __ac_put_obj().

So add code to do ClearSlabPfmemalloc for all pages of slab.

Signed-off-by: Joonsoo Kim <js1304@...il.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Christoph Lameter <cl@...ux-foundation.org>
---
This patch based on Pekka's slab/next tree

diff --git a/mm/slab.c b/mm/slab.c
index 3b4587b..45cf59a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -992,8 +992,11 @@ static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
 		 */
 		l3 = cachep->nodelists[numa_mem_id()];
 		if (!list_empty(&l3->slabs_free) && force_refill) {
-			struct slab *slabp = virt_to_slab(objp);
-			ClearPageSlabPfmemalloc(virt_to_page(slabp->s_mem));
+			int i, nr_pages = (1 << cachep->gfporder);
+			struct page *page = virt_to_head_page(objp);
+
+			for (i = 0; i < nr_pages; i++)
+				ClearPageSlabPfmemalloc(page + i);
 			clear_obj_pfmemalloc(&objp);
 			recheck_pfmemalloc_active(cachep, ac);
 			return objp;
-- 
1.7.9.5

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