From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 64BFA6B0276 for ; Sun, 9 May 2010 21:52:40 -0400 (EDT) Date: Sun, 9 May 2010 18:49:32 -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: <20100510104039.98332e67.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> <20100510104039.98332e67.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: > > Hmm. vm_flags is still 32bit..(I think it should be long long) > > Using combination of existing flags... > > #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEC_READ) > > Can be used instead of checking mapcount, I think. Ahh, yes. We can also do things like not having VM_MAY_READ/WRITE set. That's impossible on a real mapping - even if it's not readable, it is always something you could mprotect to _be_ readable. The point being, we can make the tests more explicit, and less "magic that happens to work". As long as it's ok to just say "don't migrate pages in this mapping yet, because we're still setting it up". 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