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From: Andrew Morton <akpm@linux-foundation.org>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Christoph Lameter <cl@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] migration: migrate_vmas should check "vma"
Date: Thu, 29 Jan 2009 00:18:49 -0800	[thread overview]
Message-ID: <20090129001849.9f8fdcb3.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090129101623.0d64d81b.nishimura@mxp.nes.nec.co.jp>

On Thu, 29 Jan 2009 10:16:23 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Wed, 28 Jan 2009 17:55:12 +0100, Johannes Weiner <hannes@cmpxchg.org> wrote:
> > On Wed, Jan 28, 2009 at 11:42:36AM -0500, Christoph Lameter wrote:
> > > On Wed, 28 Jan 2009, Daisuke Nishimura wrote:
> > > 
> > > > migrate_vmas() should check "vma" not "vma->vm_next" for for-loop condition.
> > > 
> > > The loop condition is checked before vma = vma->vm_next. So the last
> > > iteration of the loop will now be run with vma = NULL?
> > 
> > No, the condition is always checked before the body is executed.  The
> > assignment to vma->vm_next happens at the end of every body.
> > 
> So, I think in current code the loop body is not executed
> about the last vma in the list.
> 

Yep.

Is this serious enough to bother fixing in 2.6.29?

WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Christoph Lameter <cl@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] migration: migrate_vmas should check "vma"
Date: Thu, 29 Jan 2009 00:18:49 -0800	[thread overview]
Message-ID: <20090129001849.9f8fdcb3.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090129101623.0d64d81b.nishimura@mxp.nes.nec.co.jp>

On Thu, 29 Jan 2009 10:16:23 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Wed, 28 Jan 2009 17:55:12 +0100, Johannes Weiner <hannes@cmpxchg.org> wrote:
> > On Wed, Jan 28, 2009 at 11:42:36AM -0500, Christoph Lameter wrote:
> > > On Wed, 28 Jan 2009, Daisuke Nishimura wrote:
> > > 
> > > > migrate_vmas() should check "vma" not "vma->vm_next" for for-loop condition.
> > > 
> > > The loop condition is checked before vma = vma->vm_next. So the last
> > > iteration of the loop will now be run with vma = NULL?
> > 
> > No, the condition is always checked before the body is executed.  The
> > assignment to vma->vm_next happens at the end of every body.
> > 
> So, I think in current code the loop body is not executed
> about the last vma in the list.
> 

Yep.

Is this serious enough to bother fixing in 2.6.29?

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  reply	other threads:[~2009-01-29  8:19 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-28  7:26 [PATCH] migration: migrate_vmas should check "vma" Daisuke Nishimura
2009-01-28  7:26 ` Daisuke Nishimura
2009-01-28 16:42 ` Christoph Lameter
2009-01-28 16:42   ` Christoph Lameter
2009-01-28 16:55   ` Johannes Weiner
2009-01-28 16:55     ` Johannes Weiner
2009-01-29  1:16     ` Daisuke Nishimura
2009-01-29  1:16       ` Daisuke Nishimura
2009-01-29  8:18       ` Andrew Morton [this message]
2009-01-29  8:18         ` Andrew Morton
2009-01-30  0:30         ` Daisuke Nishimura
2009-01-30  0:30           ` Daisuke Nishimura

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