From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759386AbZERJxT (ORCPT ); Mon, 18 May 2009 05:53:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759026AbZERJsO (ORCPT ); Mon, 18 May 2009 05:48:14 -0400 Received: from mail2.shareable.org ([80.68.89.115]:58616 "EHLO mail2.shareable.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759055AbZERJsN (ORCPT ); Mon, 18 May 2009 05:48:13 -0400 Date: Mon, 18 May 2009 10:48:08 +0100 From: Jamie Lokier To: Alan Cox Cc: Andi Kleen , 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: <20090518094808.GA12041@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> <20090518093136.152a1bb7@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090518093136.152a1bb7@lxorguk.ukuu.org.uk> 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 Alan Cox wrote: > > System calls don't trigger SIGSEGVs so they can't rely on that when > > calling read(). I'm not sure how they handle that. > > Usually by touching the pages before the syscall. Makes sense. > (You can't rely on -EFAULT either in POSIX, its optional that it > bothers to tell you and for example on MMUless it may well not) On MMUless you wouldn't use page protection as a GC technique :-) Is EFAULT really optional on systems with page protection? -- Jamie