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ksm: fix mlockfreed to munlocked

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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>
This commit is contained in:
Hugh Dickins 2009-12-14 17:59:22 -08:00 committed by Linus Torvalds
parent 08beca44df
commit 73848b4684
3 changed files with 8 additions and 3 deletions
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3
mm/internal.h
View file

@ -105,9 +105,10 @@ static inline int is_mlocked_vma(struct vm_area_struct *vma, struct page *page)
}
/*
* 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

4
mm/ksm.c
View file

@ -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 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
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;

4
mm/mlock.c
View file

@ -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));