ksm: fix mlockfreed to munlocked

2.6.33-rc1 commit 73848b4684e84a84cfd1555af78d41158f31e16b, adjusted
to include 31e855ea7173bdb0520f9684580423a9560f66e0's movement of
the unlock_page(oldpage), but omit other intervening cleanups.

When KSM merges an mlocked page, it has been forgetting to munlock it:
that's been left to free_page_mlock(), which reports it in /proc/vmstat
as unevictable_pgs_mlockfreed instead of unevictable_pgs_munlocked,
which indicates that such pages _might_ be left unevictable for long
after they should be evictable.  Call munlock_vma_page() to fix that.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index bd6f0e466f6c..2e05c97b04f5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -99,14 +99,14 @@ void mlock_vma_page(struct page *page)
  * not get another chance to clear PageMlocked.  If we successfully
  * isolate the page and try_to_munlock() detects other VM_LOCKED vmas
  * mapping the page, it will restore the PageMlocked state, unless the page
- * is mapped in a non-linear vma.  So, we go ahead and SetPageMlocked(),
+ * is mapped in a non-linear vma.  So, we go ahead and ClearPageMlocked(),
  * perhaps redundantly.
  * If we lose the isolation race, and the page is mapped by other VM_LOCKED
  * vmas, we'll detect this in vmscan--via try_to_munlock() or try_to_unmap()
  * either of which will restore the PageMlocked state by calling
  * mlock_vma_page() above, if it can grab the vma's mmap sem.
  */
-static void munlock_vma_page(struct page *page)
+void munlock_vma_page(struct page *page)
 {
 	BUG_ON(!PageLocked(page));