From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 346D36B01AD for ; Sun, 20 Jun 2010 03:15:18 -0400 (EDT) Date: Sun, 20 Jun 2010 15:14:46 +0800 From: Wu Fengguang Subject: Re: [PATCH] [31/31] HWPOISON: Add a madvise() injector for soft page offlining Message-ID: <20100620071446.GA21743@localhost> References: <20091208211647.9B032B151F@basil.firstfloor.org> <20100619132055.GK18946@basil.fritz.box> <20100619133000.GL18946@basil.fritz.box> <20100619140933.GM18946@basil.fritz.box> <20100619195242.GS18946@basil.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Michael Kerrisk Cc: Andi Kleen , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" List-ID: On Sun, Jun 20, 2010 at 02:19:35PM +0800, Michael Kerrisk wrote: > Hi Andi, > On Sat, Jun 19, 2010 at 9:52 PM, Andi Kleen wrote: > >> .TP > >> .BR MADV_SOFT_OFFLINE " (Since Linux 2.6.33) > >> Soft offline the pages in the range specified by > >> .I addr > >> and > >> .IR length . > >> This memory of each page in the specified range is copied to a new page, > > > > Actually there are some cases where it's also dropped if it's cached page. > > > > Perhaps better would be something more fuzzy like > > > > "the contents are preserved" > > The problem to me is that this gets so fuzzy that it's hard to > understand the meaning (I imagine many readers will ask: "What does it > mean that the contents are preserved"?). Would you be able to come up > with a wording that is a little miore detailed? That is, MADV_SOFT_OFFLINE won't lose data. If a process writes "1" to some virtual address and then called madvice(MADV_SOFT_OFFLINE) on that virtual address, it can continue to read "1" from that virtual address. MADV_SOFT_OFFLINE "transparently" replaces the underlying physical page frame with a new one that contains the same data "1". The original page frame is offlined, and the new page frame may be installed lazily. Thanks, Fengguang -- 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