From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757540AbZEOOhh (ORCPT ); Fri, 15 May 2009 10:37:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752055AbZEOOh2 (ORCPT ); Fri, 15 May 2009 10:37:28 -0400 Received: from mail2.shareable.org ([80.68.89.115]:41369 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbZEOOh1 (ORCPT ); Fri, 15 May 2009 10:37:27 -0400 Date: Fri, 15 May 2009 15:37:27 +0100 From: Jamie Lokier To: Andi Kleen Cc: Vitaly Mayatskikh , Josef Bacik , sandeen@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] Perform check in iov_iter_fault_in_readable() by check_readable_bytes() Message-ID: <20090515143726.GE8235@shareable.org> References: <1242317939-15392-1-git-send-email-v.mayatskih@gmail.com> <1242317939-15392-3-git-send-email-v.mayatskih@gmail.com> <87k54iq2gv.fsf@basil.nowhere.org> <871vqqkdf0.wl%vmayatsk@redhat.com> <20090515093838.GB16682@one.firstfloor.org> <20090515134315.GB8235@shareable.org> <20090515140137.GF16682@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090515140137.GF16682@one.firstfloor.org> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > > It would be quite nice if it were safe to call read(), get EFAULT > > Even with that patch it is not safe, not even for write, because > it's racy. That's not necessarily a problem for the applications I described, because they can be made to only increase access in parallel with access; decreasing access can be synchronised over the whole program. But I agree with you, as no application should depend on such subtle details, which would probably be broken again in a future kernel anyway. -- Jamie