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 <gorcunov@openvz.org>
Reported-by: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/fremap.c b/mm/fremap.c
index 34feba6..2c5646f 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -82,13 +82,10 @@
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