From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 4ED0F6B01F1 for ; Mon, 16 Aug 2010 05:21:11 -0400 (EDT) Date: Mon, 16 Aug 2010 18:19:35 +0900 From: Naoya Horiguchi Subject: Re: [PATCH 0/9] Hugepage migration (v2) Message-ID: <20100816091935.GB3388@spritzera.linux.bs1.fc.nec.co.jp> References: <1281432464-14833-1-git-send-email-n-horiguchi@ah.jp.nec.com> <20100812075323.GA6112@spritzera.linux.bs1.fc.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Andi Kleen , Andrew Morton , Mel Gorman , Wu Fengguang , Jun'ichi Nomura , linux-mm , LKML List-ID: On Fri, Aug 13, 2010 at 07:47:21AM -0500, Christoph Lameter wrote: > On Thu, 12 Aug 2010, Naoya Horiguchi wrote: > > > > Can you also avoid refcounts being increased during migration? > > > > Yes. I think this will be done in above-mentioned refactoring. > > Thats not what I meant. Can you avoid other processors increasing > refcounts (direct I/O etc?) on any page struct of the huge page while > migration is running? In my understanding, in current code "other processors increasing refcount during migration" can happen both in non-hugepage direct I/O and in hugepage direct I/O in the similar way (i.e. get_user_pages_fast() from dio_refill_pages()). So I think there is no specific problem to hugepage. Or am I missing your point? > > > This patch only handles migration under direct I/O. > > For the opposite (direct I/O under migration) it's not true. > > I wrote additional patches (later I'll reply to this email) > > for solving locking problem. Could you review them? > > Sure. > > > (Maybe these patches are beyond the scope of hugepage migration patch, > > so is it better to propose them separately?) > > Migration with known races is really not what we want in the kernel. Yes. Thanks, Naoya Horiguchi -- 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