ksm: fix mlockfreed to munlocked
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 (and
whinges "Page flag mlocked set for process" in mmotm, whereas mainline is
silently forgiving). Call munlock_vma_page() to fix that.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Chris Wright <chrisw@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/internal.h b/mm/internal.h
index cb7d92d..a4b927c 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -105,9 +105,10 @@
}
/*
- * must be called with vma's mmap_sem held for read, and page locked.
+ * must be called with vma's mmap_sem held for read or write, and page locked.
*/
extern void mlock_vma_page(struct page *page);
+extern void munlock_vma_page(struct page *page);
/*
* Clear the page's PageMlocked(). This can be useful in a situation where
diff --git a/mm/ksm.c b/mm/ksm.c
index 74878568..af5f571 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -34,6 +34,7 @@
#include <linux/ksm.h>
#include <asm/tlbflush.h>
+#include "internal.h"
/*
* A few notes about the KSM scanning process,
@@ -762,6 +763,9 @@
pages_identical(page, kpage))
err = replace_page(vma, page, kpage, orig_pte);
+ if ((vma->vm_flags & VM_LOCKED) && !err)
+ munlock_vma_page(page);
+
unlock_page(page);
out:
return err;
diff --git a/mm/mlock.c b/mm/mlock.c
index 48691fb..adcbe90 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -99,14 +99,14 @@
* 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));
