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Date: Wed, 4 Nov 2015 10:26:01 +0900 From: Minchan Kim <minchan@...nel.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, Michael Kerrisk <mtk.manpages@...il.com>, linux-api@...r.kernel.org, Hugh Dickins <hughd@...gle.com>, Johannes Weiner <hannes@...xchg.org>, Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, Jason Evans <je@...com>, Daniel Micay <danielmicay@...il.com>, "Kirill A. Shutemov" <kirill@...temov.name>, Shaohua Li <shli@...nel.org>, Michal Hocko <mhocko@...e.cz>, yalin.wang2010@...il.com, Minchan Kim <minchan@...nel.org> Subject: [PATCH v2 07/13] mm: mark stable page dirty in KSM 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@...gle.com> Signed-off-by: Minchan Kim <minchan@...nel.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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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