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@xxxxxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> --- mm/ksm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/ksm.c b/mm/ksm.c index 30cb0f753e19..5e967536c38e 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1015,6 +1015,12 @@ 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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>