From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 202F16B01E3 for ; Wed, 12 May 2010 16:52:13 -0400 (EDT) Date: Wed, 12 May 2010 21:51:50 +0100 From: Mel Gorman Subject: Re: [PATCH] mm,migration: Avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks Message-ID: <20100512205150.GL24989@csn.ul.ie> References: <20100511085752.GM26611@csn.ul.ie> <20100512092239.2120.A69D9226@jp.fujitsu.com> <20100512125427.d1b170ba.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20100512125427.d1b170ba.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: KOSAKI Motohiro , Linus Torvalds , KAMEZAWA Hiroyuki , Linux-MM , LKML , Minchan Kim , Christoph Lameter , Andrea Arcangeli , Rik van Riel , Peter Zijlstra List-ID: On Wed, May 12, 2010 at 12:54:27PM -0700, Andrew Morton wrote: > On Wed, 12 May 2010 09:23:44 +0900 (JST) > KOSAKI Motohiro wrote: > > > > diff --git a/fs/exec.c b/fs/exec.c > > > index 725d7ef..13f8e7f 100644 > > > --- a/fs/exec.c > > > +++ b/fs/exec.c > > > @@ -242,9 +242,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm) > > > * use STACK_TOP because that can depend on attributes which aren't > > > * configured yet. > > > */ > > > + BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); > > > > Can we use BUILD_BUG_ON()? > > That's vastly preferable - I made that change. > I will be surprised if it works. On x86, that is #define VM_STACK_FLAGS (VM_GROWSDOWN | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT) #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS #define VM_DATA_DEFAULT_FLAGS \ (((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \ VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) so VM_STACK_FLAGS is depending on the value of current->personality which we don't know at build time. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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