From mboxrd@z Thu Jan 1 00:00:00 1970 From: Minchan Kim Subject: [PATCH v3 07/17] mm: mark stable page dirty in KSM Date: Thu, 12 Nov 2015 13:33:03 +0900 Message-ID: <1447302793-5376-8-git-send-email-minchan@kernel.org> References: <1447302793-5376-1-git-send-email-minchan@kernel.org> Return-path: In-Reply-To: <1447302793-5376-1-git-send-email-minchan@kernel.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael Kerrisk , linux-api@vger.kernel.org, Hugh Dickins , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Jason Evans , Daniel Micay , "Kirill A. Shutemov" , Shaohua Li , Michal Hocko , yalin.wang2010@gmail.com, Minchan Kim List-Id: linux-api@vger.kernel.org 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 Signed-off-by: Minchan Kim --- 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org