From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id D195F6B0034 for ; Mon, 8 Jul 2013 18:30:12 -0400 (EDT) Received: by mail-ob0-f175.google.com with SMTP id xn12so6232854obc.34 for ; Mon, 08 Jul 2013 15:30:12 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20130708180501.GB6490@redhat.com> References: <1372901537-31033-1-git-send-email-ccross@android.com> <20130704202232.GA19287@redhat.com> <20130708180424.GA6490@redhat.com> <20130708180501.GB6490@redhat.com> From: KOSAKI Motohiro Date: Mon, 8 Jul 2013 18:29:51 -0400 Message-ID: Subject: Re: [PATCH 1/1] mm: mempolicy: fix mbind_range() && vma_adjust() interaction Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: Colin Cross , Andrew Morton , Hugh Dickins , Linus Torvalds , "Hampson, Steven T" , lkml , Kyungmin Park , Christoph Hellwig , John Stultz , Rob Landley , Arnd Bergmann , Cyrill Gorcunov , David Rientjes , Davidlohr Bueso , Kees Cook , Al Viro , Mel Gorman , Michel Lespinasse , Rik van Riel , Konstantin Khlebnikov , Peter Zijlstra , Rusty Russell , "Eric W. Biederman" , Srikar Dronamraju , KAMEZAWA Hiroyuki , Michal Hocko , Anton Vorontsov , Pekka Enberg , Shaohua Li , Sasha Levin , Johannes Weiner , Ingo Molnar , "open list:DOCUMENTATION" , "open list:MEMORY MANAGEMENT" , "open list:GENERIC INCLUDE/A..." On Mon, Jul 8, 2013 at 2:05 PM, Oleg Nesterov wrote: > vma_adjust() does vma_set_policy(vma, vma_policy(next)) and this > is doubly wrong: > > 1. This leaks vma->vm_policy if it is not NULL and not equal to > next->vm_policy. > > This can happen if vma_merge() expands "area", not prev (case 8). > > 2. This sets the wrong policy if vma_merge() joins prev and area, > area is the vma the caller needs to update and it still has the > old policy. > > Revert 1444f92c "mm: merging memory blocks resets mempolicy" which > introduced these problems. Yes, I believe 1444f92c is wrong and should be reverted. > > Change mbind_range() to recheck mpol_equal() after vma_merge() to > fix the problem 1444f92c tried to address. > > Signed-off-by: Oleg Nesterov > Cc: > --- > mm/mempolicy.c | 6 +++++- > mm/mmap.c | 2 +- > 2 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 7431001..4baf12e 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -732,7 +732,10 @@ static int mbind_range(struct mm_struct *mm, unsigned long start, > if (prev) { > vma = prev; > next = vma->vm_next; > - continue; > + if (mpol_equal(vma_policy(vma), new_pol)) > + continue; > + /* vma_merge() joined vma && vma->next, case 8 */ case 3 makes the same scenario? Acked-by: KOSAKI Motohiro -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org