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 9971B6B0276 for ; Sun, 9 May 2010 21:33:59 -0400 (EDT) Date: Sun, 9 May 2010 18:30:51 -0700 (PDT) From: Linus Torvalds Subject: Re: [PATCH 2/2] mm,migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack In-Reply-To: <20100510094050.8cb79143.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <1273188053-26029-1-git-send-email-mel@csn.ul.ie> <1273188053-26029-3-git-send-email-mel@csn.ul.ie> <20100507105712.18fc90c4.kamezawa.hiroyu@jp.fujitsu.com> <20100509192145.GI4859@csn.ul.ie> <20100510094050.8cb79143.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Mel Gorman , Andrew Morton , Linux-MM , LKML , Minchan Kim , Christoph Lameter , Andrea Arcangeli , Rik van Riel , Peter Zijlstra List-ID: On Mon, 10 May 2010, KAMEZAWA Hiroyuki wrote: > > But, move_page_tables()'s failure is not a big problem. Well, yes and no. It's not a problem because it fails, but because it does the allocation. Which means that we can't protect the thing with the (natural) anon_vma locking. > Considering cost, as Mel shows, "don't migrate apges in exec's stack" seems > reasonable. But, I still doubt this check. Well, I actually always liked Mel's patch, the one he calls "magic". I think it's _less_ magic than the crazy "let's create another vma and anon_vma chain just because migration has it's thumb up its ass". So I never disliked that patch. I'm perfectly happy with a "don't migrate these pages at all, because they are in a half-way state in the middle of execve stack magic". Linus -- 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