linux-kernel - [PATCH v3 02/16] slub: use free_page instead of put

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Date:	Tue, 18 Sep 2012 18:11:56 +0400
From:	Glauber Costa <glommer@...allels.com>
To:	<linux-kernel@...r.kernel.org>
Cc:	<cgroups@...r.kernel.org>, <kamezawa.hiroyu@...fujitsu.com>,
	<devel@...nvz.org>, Tejun Heo <tj@...nel.org>,
	<linux-mm@...ck.org>, Suleiman Souhlal <suleiman@...gle.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mel Gorman <mgorman@...e.de>,
	David Rientjes <rientjes@...gle.com>,
	Glauber Costa <glommer@...allels.com>,
	Pekka Enberg <penberg@...nel.org>
Subject: [PATCH v3 02/16] slub: use free_page instead of put_page for freeing kmalloc allocation

When freeing objects, the slub allocator will most of the time free
empty pages by calling __free_pages(). But high-order kmalloc will be
diposed by means of put_page() instead. It makes no sense to call
put_page() in kernel pages that are provided by the object allocators,
so we shouldn't be doing this ourselves. Aside from the consistency
change, we don't change the flow too much. put_page()'s would call its
dtor function, which is __free_pages. We also already do all of the
Compound page tests ourselves, and the Mlock test we lose don't really
matter.

[v2: modified Changelog ]

Signed-off-by: Glauber Costa <glommer@...allels.com>
Acked-by: Christoph Lameter <cl@...ux.com>
CC: David Rientjes <rientjes@...gle.com>
CC: Pekka Enberg <penberg@...nel.org>
---
 mm/slub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index 9f86353..09a91d0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3451,7 +3451,7 @@ void kfree(const void *x)
 	if (unlikely(!PageSlab(page))) {
 		BUG_ON(!PageCompound(page));
 		kmemleak_free(x);
-		put_page(page);
+		__free_pages(page, compound_order(page));
 		return;
 	}
 	slab_free(page->slab, page, object, _RET_IP_);
-- 
1.7.11.4

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