From 0bf073315cb29d2e9e68b6c5da97862a519e3320 Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Wed, 4 Jun 2014 16:06:41 -0700 Subject: [PATCH] mm: softdirty: make freshly remapped file pages being softdirty unconditionally Hugh reported: | I noticed your soft_dirty work in install_file_pte(): which looked | good at first, until I realized that it's propagating the soft_dirty | of a pte it's about to zap completely, to the unrelated entry it's | about to insert in its place. Which seems very odd to me. Indeed this code ends up being nop in result -- pte_file_mksoft_dirty() operates with pte_t argument and returns new pte_t which were never used after. After looking more I think what we need is to soft-dirtify all newely remapped file pages because it should look like a new mapping for memory tracker. Signed-off-by: Cyrill Gorcunov Reported-by: Hugh Dickins Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/fremap.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/mm/fremap.c b/mm/fremap.c index 34feba60a17e..2c5646f11f41 100644 --- a/mm/fremap.c +++ b/mm/fremap.c @@ -82,13 +82,10 @@ static int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, ptfile = pgoff_to_pte(pgoff); - if (!pte_none(*pte)) { - if (pte_present(*pte) && pte_soft_dirty(*pte)) - pte_file_mksoft_dirty(ptfile); + if (!pte_none(*pte)) zap_pte(mm, vma, addr, pte); - } - set_pte_at(mm, addr, pte, ptfile); + set_pte_at(mm, addr, pte, pte_file_mksoft_dirty(ptfile)); /* * We don't need to run update_mmu_cache() here because the "file pte" * being installed by install_file_pte() is not a real pte - it's a