[PATCH v4 06/16] mm: mark stable page dirty in KSM

Path	csiph.com!goblin3!goblin1!goblin.stu.neva.ru!news.panservice.it!bofh.it!news.nic.it!robomod
From	Minchan Kim <minchan@kernel.org>
Newsgroups	linux.kernel
Subject	[PATCH v4 06/16] mm: mark stable page dirty in KSM
Date	Fri, 20 Nov 2015 09:10:02 +0100
Message-ID	<qwOVA-4AF-27@gated-at.bofh.it> (permalink)
References	<qwOVA-4AF-7@gated-at.bofh.it>
X-Original-To	Andrew Morton <akpm@linux-foundation.org>
X-Original-Senderip	156.147.1.121
X-Original-Mailfrom	minchan@kernel.org
X-Original-Senderip	10.177.223.161
X-Original-Mailfrom	minchan@kernel.org
X-Mailer	git-send-email 1.9.1
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	37
Organization	linux.* mail to news gateway
X-Original-Cc	linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael Kerrisk <mtk.manpages@gmail.com>, linux-api@vger.kernel.org, Hugh Dickins <hughd@google.com>, Johannes Weiner <hannes@cmpxchg.org>, Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Jason Evans <je@fb.com>, Daniel Micay <danielmicay@gmail.com>, "Kirill A. Shutemov" <kirill@shutemov.name>, Shaohua Li <shli@kernel.org>, Michal Hocko <mhocko@suse.cz>, yalin.wang2010@gmail.com, Andy Lutomirski <luto@amacapital.net>, Minchan Kim <minchan@kernel.org>
X-Original-Date	Fri, 20 Nov 2015 17:02:38 +0900
X-Original-Message-ID	<1448006568-16031-7-git-send-email-minchan@kernel.org>
X-Original-References	<1448006568-16031-1-git-send-email-minchan@kernel.org>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1273783

Show key headers only | View raw

The MADV_FREE patchset changes page reclaim to simply free a clean
anonymous page with no dirty ptes, instead of swapping it out; but
KSM uses clean write-protected ptes to reference the stable ksm page.
So be sure to mark that page dirty, so it's never mistakenly discarded.

[hughd: adjusted comments]
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/ksm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/ksm.c b/mm/ksm.c
index 7ee101eaacdf..18d2b7afecff 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1053,6 +1053,12 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
 			 */
 			set_page_stable_node(page, NULL);
 			mark_page_accessed(page);
+			/*
+			 * Page reclaim just frees a clean page with no dirty
+			 * ptes: make sure that the ksm page would be swapped.
+			 */
+			if (!PageDirty(page))
+				SetPageDirty(page);
 			err = 0;
 		} else if (pages_identical(page, kpage))
 			err = replace_page(vma, page, kpage, orig_pte);
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

[PATCH v4 06/16] mm: mark stable page dirty in KSM Minchan Kim <minchan@kernel.org> - 2015-11-20 09:10 +0100

csiph-web