Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755553AbZFBNkb (ORCPT ); Tue, 2 Jun 2009 09:40:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753876AbZFBNkY (ORCPT ); Tue, 2 Jun 2009 09:40:24 -0400 Received: from cantor.suse.de ([195.135.220.2]:49229 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752522AbZFBNkY (ORCPT ); Tue, 2 Jun 2009 09:40:24 -0400 Date: Tue, 2 Jun 2009 15:40:24 +0200 From: Nick Piggin To: Andi Kleen Cc: Wu Fengguang , "hugh@veritas.com" , "riel@redhat.com" , "akpm@linux-foundation.org" , "chris.mason@oracle.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3 Message-ID: <20090602134024.GA19390@wotan.suse.de> References: <20090528122357.GM6920@wotan.suse.de> <20090528135428.GB16528@localhost> <20090601115046.GE5018@wotan.suse.de> <20090601183225.GS1065@one.firstfloor.org> <20090602120042.GB1392@wotan.suse.de> <20090602124757.GG1065@one.firstfloor.org> <20090602125713.GG1392@wotan.suse.de> <20090602132538.GK1065@one.firstfloor.org> <20090602132441.GC6262@wotan.suse.de> <20090602134126.GM1065@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090602134126.GM1065@one.firstfloor.org> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2297 Lines: 54 On Tue, Jun 02, 2009 at 03:41:26PM +0200, Andi Kleen wrote: > On Tue, Jun 02, 2009 at 03:24:41PM +0200, Nick Piggin wrote: > > On Tue, Jun 02, 2009 at 03:25:38PM +0200, Andi Kleen wrote: > > > The reason this code double checks is that someone could have > > > a reference (remember we can come in any time) we cannot kill immediately. > > > > Can't kill what? The page is gone from pagecache. It may remain > > other kernel references, but I don't see why this code will > > consider this as a failure (and not, for example, a raised error > > count). > > It's a failure because the page was still used and not successfully > isolated. But you're predicating success on page_count, so there can be other users anyway. You do check page_count later and emit a different message in this case, but even that isn't enough to tell you if it has no more users. I wouldn't have thought it's worth the complication, but there is nothing preventing you using my truncate function and also keeping this error check to test afterwards. > > + * remove_from_page_cache assumes (mapping && !mapped) > > + */ > > + if (page_mapping(p) && !page_mapped(p)) { > > Ok you're right. That one is not needed. I will remove it. > > > > > > > User page tables was on the todo list, these are actually relatively > > > easy. The biggest issue is to detect them. > > > > > > Metadata would likely need file system callbacks, which I would like to > > > avoid at this point. > > > > So I just don't know why you argue the point that you have lots > > of large holes left. > > I didn't argue that. My point was just that I currently don't have > data what holes are the worst on given workloads. If I figure out at > some point that writeback pages are a significant part of some important > workload I would be interested in tackling them. > That said I think that's unlikely, but I'm not ruling it out. Well, it sounds like maybe there is a sane way to do them with your IO interception... but anyway let's not worry about this right now ;) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/