Commit 73848b46 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

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: default avatarHugh 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: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 08beca44

mm/internal.h

+2 −1
Original line number Diff line number Diff line
@@ -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

mm/ksm.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

mm/mlock.c

+2 −2
Original line number Diff line number Diff line
@@ -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));

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