Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760772AbZKZQUN (ORCPT ); Thu, 26 Nov 2009 11:20:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760758AbZKZQUL (ORCPT ); Thu, 26 Nov 2009 11:20:11 -0500 Received: from gir.skynet.ie ([193.1.99.77]:44476 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755854AbZKZQUK (ORCPT ); Thu, 26 Nov 2009 11:20:10 -0500 Date: Thu, 26 Nov 2009 16:20:12 +0000 From: Mel Gorman To: Hugh Dickins Cc: Andrew Morton , Izik Eidus , Andrea Arcangeli , Chris Wright , Rik van Riel , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/9] ksm: fix mlockfreed to munlocked Message-ID: <20091126162011.GG13095@csn.ul.ie> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3358 Lines: 84 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 Acked-by: Mel Gorman > --- > 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 > > #include > +#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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/