Messages in this thread Patch in this message | | | Date | Thu, 26 Nov 2009 16:20:12 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH 1/9] ksm: fix mlockfreed to munlocked |
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On Tue, Nov 24, 2009 at 04:40:55PM +0000, Hugh Dickins wrote: > 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>
Acked-by: Mel Gorman <mel@csn.ul.ie>
> --- > Is this a fix that I ought to backport to 2.6.32? It does rely on part of > an earlier patch (moved unlock_page down), so does not apply cleanly as is. > > mm/internal.h | 3 ++- > mm/ksm.c | 4 ++++ > mm/mlock.c | 4 ++-- > 3 files changed, 8 insertions(+), 3 deletions(-) > > --- ksm0/mm/internal.h 2009-11-14 10:17:02.000000000 +0000 > +++ ksm1/mm/internal.h 2009-11-22 20:39:56.000000000 +0000 > @@ -105,9 +105,10 @@ static inline int is_mlocked_vma(struct > } > > /* > - * 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 > --- ksm0/mm/ksm.c 2009-11-14 10:17:02.000000000 +0000 > +++ ksm1/mm/ksm.c 2009-11-22 20:39:56.000000000 +0000 > @@ -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 > 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; > --- ksm0/mm/mlock.c 2009-11-14 10:17:02.000000000 +0000 > +++ ksm1/mm/mlock.c 2009-11-22 20:39:56.000000000 +0000 > @@ -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)); > >
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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