From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 8E0C96B0087 for ; Thu, 28 May 2009 08:15:30 -0400 (EDT) Date: Thu, 28 May 2009 14:15:41 +0200 From: Nick Piggin Subject: Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3 Message-ID: <20090528121541.GL6920@wotan.suse.de> References: <200905271012.668777061@firstfloor.org> <20090527201239.C2C9C1D0294@basil.firstfloor.org> <20090528082616.GG6920@wotan.suse.de> <20090528095934.GA10678@localhost> <20090528101111.GE1065@one.firstfloor.org> <20090528103300.GA15133@localhost> <20090528105103.GG1065@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090528105103.GG1065@one.firstfloor.org> Sender: owner-linux-mm@kvack.org 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" List-ID: On Thu, May 28, 2009 at 12:51:03PM +0200, Andi Kleen wrote: > On Thu, May 28, 2009 at 06:33:00PM +0800, Wu Fengguang wrote: > > > > > You haven't waited on writeback here AFAIKS, and have you > > > > > *really* verified it is safe to call delete_from_swap_cache? > > > > > > > > Good catch. I'll soon submit patches for handling the under > > > > read/write IO pages. In this patchset they are simply ignored. > > > > > > Yes, we assume the IO device does something sensible with the poisoned > > > cache lines and aborts. Later we can likely abort IO requests in a early > > > stage on the Linux, but that's more advanced. > > > > > > The question is if we need to wait on writeback for correctness? > > > > Not necessary. Because I'm going to add a me_writeback() handler. > > Ok but without it. Let's assume me_writeback() is in the future. For correctness for what? You can't remove a page from swapcache or pagecache under writeback because then the mm thinks that location is not being used. > I'm mainly interested in correctness (as in not crashing) of this > version now. > > Also writeback seems to be only used by nfs/afs/nilfs2, not in > the normal case, unless I'm misreading the code. I don't follow. What writeback are you talking about? > > The nilfs2 case seems weird, I haven't completely read that. > > > Then the writeback pages simply won't reach here. And it won't > > magically go into writeback state, since the page has been locked. > > But since we take the page lock they should not be in writeback anyways, > no? No. PG_writeback was introduced so as to reduce page lock hold times (most of writeback runs without page lock held). -- 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