Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262427AbTENOyR (ORCPT ); Wed, 14 May 2003 10:54:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262431AbTENOyR (ORCPT ); Wed, 14 May 2003 10:54:17 -0400 Received: from holomorphy.com ([66.224.33.161]:25540 "EHLO holomorphy") by vger.kernel.org with ESMTP id S262427AbTENOyQ (ORCPT ); Wed, 14 May 2003 10:54:16 -0400 Date: Wed, 14 May 2003 08:06:53 -0700 From: William Lee Irwin III To: Dave McCracken Cc: Andrew Morton , mika.penttila@kolumbus.fi, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: Race between vmtruncate and mapped areas? Message-ID: <20030514150653.GM8978@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Dave McCracken , Andrew Morton , mika.penttila@kolumbus.fi, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <154080000.1052858685@baldur.austin.ibm.com> <20030513181018.4cbff906.akpm@digeo.com> <18240000.1052924530@baldur.austin.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18240000.1052924530@baldur.austin.ibm.com> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1265 Lines: 26 On Tuesday, May 13, 2003 18:10:18 -0700 Andrew Morton wrote: >> That's the one. Process is sleeping on I/O in filemap_nopage(), wakes up >> after the truncate has done its thing and the page gets instantiated in >> pagetables. >> But it's an anon page now. So the application (which was racy anyway) >> gets itself an anonymous page. On Wed, May 14, 2003 at 10:02:10AM -0500, Dave McCracken wrote: > Which the application thinks is still part of the file, and will expect its > changes to be written back. Granted, if the page fault occurred just after > the truncate it'd get SIGBUS, so it's clearly not a robust assumption, but > it will result in unexpected behavior. Note that if the application later > extends the file to include this page it could result in a corrupted file, > since all the pages around it will be written properly. Well, for this one I'd say the app loses; it was its own failure to synchronize truncation vs. access, at least given that the kernel doesn't oops. -- wli - 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/