From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261178AbVHATbm (ORCPT ); Mon, 1 Aug 2005 15:31:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261186AbVHAT31 (ORCPT ); Mon, 1 Aug 2005 15:29:27 -0400 Received: from silver.veritas.com ([143.127.12.111]:29966 "EHLO silver.veritas.com") by vger.kernel.org with ESMTP id S261178AbVHAT2F (ORCPT ); Mon, 1 Aug 2005 15:28:05 -0400 Date: Mon, 1 Aug 2005 20:29:40 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Linus Torvalds cc: Nick Piggin , Robin Holt , Andrew Morton , Roland McGrath , Martin Schwidefsky , linux-mm@kvack.org, linux-kernel Subject: Re: [patch 2.6.13-rc4] fix get_user_pages bug In-Reply-To: Message-ID: References: <20050801032258.A465C180EC0@magilla.sf.frob.com> <42EDDB82.1040900@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 01 Aug 2005 19:28:04.0516 (UTC) FILETIME=[2355F640:01C596CF] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 1 Aug 2005, Linus Torvalds wrote: > > that "continue" will continue without the spinlock held, and now do Yes, I was at last about to reply on that point and others. I'll make those comments in a separate mail to Nick and all. > Instead, I'd suggest changing the logic for "lookup_write". Make it > require that the page table entry is _dirty_ (not writable), and then Attractive, I very much wanted to do that rather than change all the arches, but I think s390 rules it out: its pte_mkdirty does nothing, its pte_dirty just says no. Whether your patch suits all other uses of (__)follow_page I've not investigated (and I don't see how you can go without the set_page_dirty if it was necessary before); but at present see no alternative to something like Nick's patch, though I'd much prefer smaller. Or should we change s390 to set a flag in the pte just for this purpose? Hugh