From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265934AbUBCI3U (ORCPT ); Tue, 3 Feb 2004 03:29:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265937AbUBCI3U (ORCPT ); Tue, 3 Feb 2004 03:29:20 -0500 Received: from mx1.elte.hu ([157.181.1.137]:19146 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S265934AbUBCI3O (ORCPT ); Tue, 3 Feb 2004 03:29:14 -0500 Date: Tue, 3 Feb 2004 09:29:49 +0100 From: Ingo Molnar To: Linus Torvalds Cc: Roland McGrath , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] restore protections after forced fault in get_user_pages Message-ID: <20040203082949.GA1116@elte.hu> References: <200402030009.i1309TeY016316@magilla.sf.frob.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: SpamAssassin 2.60 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Linus Torvalds wrote: > > I think this question is orthogonal to my concern about follow_page. > > The follow_page issue should be fixable by just marking the _page_ > dirty inside the ptrace routines. I think we do that anyway (or we'd > already be buggy wrt perfectly normal writes). the follow_page() issue could be handled like the 4/4 patch does it: a repeat-until loop of manual-fault + lookup-pte (we break out of the loop if the manual fault fails or when the lookup is successful). The race window is so small that the repeating solution is i think far superior to artificially dirtying the pte. Ingo