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Date: Fri, 09 Apr 2010 11:57:00 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Christian Ehrhardt <uni@...e.de> Cc: Andrea Arcangeli <aarcange@...hat.com>, Avi Kivity <avi@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Rik van Riel <riel@...hat.com>, Ingo Molnar <mingo@...e.hu>, akpm@...ux-foundation.org, Linus Torvalds <torvalds@...ux-foundation.org>, linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, Benjamin Herrenschmidt <benh@...nel.crashing.org>, David Miller <davem@...emloft.net>, Hugh Dickins <hugh.dickins@...cali.co.uk>, Mel Gorman <mel@....ul.ie>, Nick Piggin <npiggin@...e.de> Subject: Re: [PATCH 05/13] mm: Make use of the anon_vma ref count On Fri, 2010-04-09 at 09:04 +0200, Christian Ehrhardt wrote: > Hi, > > On Thu, Apr 08, 2010 at 09:17:42PM +0200, Peter Zijlstra wrote: > > @@ -302,23 +307,33 @@ again: > > goto out; > > > > anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); > > - spin_lock(&anon_vma->lock); > > + if (!atomic_inc_not_zero(&anon_vma->ref)) > > + anon_vma = NULL; > > > > if (page_rmapping(page) != anon_vma) { > > - spin_unlock(&anon_vma->lock); > > + anon_vma_put(anon_vma); > > goto again; > > } > > AFAICS anon_vma_put might be called with anon_vma == NULL here which > will oops on the ref count. Not sure if > > page_rmapping(page) == anon_vma == NULL > > is possible, too. Gah, you're right, thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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