linux-kernel - [PATCHv6 03/22] memcg, thp: charge huge cache pages

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Date:	Mon, 23 Sep 2013 15:05:31 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>, Hugh Dickins <hughd@...gle.com>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Hillf Danton <dhillf@...il.com>, Dave Hansen <dave@...1.net>,
	Ning Qu <quning@...gle.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: [PATCHv6 03/22] memcg, thp: charge huge cache pages

mem_cgroup_cache_charge() has check for PageCompound(). The check
prevents charging huge cache pages.

I don't see a reason why the check is present. Looks like it's just
legacy (introduced in 52d4b9a memcg: allocate all page_cgroup at boot).

Let's just drop it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Acked-by: Michal Hocko <mhocko@...e.cz>
---
 mm/memcontrol.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d5ff3ce130..0b87a1bd25 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3963,8 +3963,7 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
 
 	if (mem_cgroup_disabled())
 		return 0;
-	if (PageCompound(page))
-		return 0;
+	VM_BUG_ON(PageCompound(page) && !PageTransHuge(page));
 
 	if (!PageSwapCache(page))
 		ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
-- 
1.8.4.rc3

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