From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261288AbVBVV6y (ORCPT ); Tue, 22 Feb 2005 16:58:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261289AbVBVV6y (ORCPT ); Tue, 22 Feb 2005 16:58:54 -0500 Received: from fire.osdl.org ([65.172.181.4]:22213 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S261288AbVBVV6w (ORCPT ); Tue, 22 Feb 2005 16:58:52 -0500 Date: Tue, 22 Feb 2005 13:59:25 -0800 (PST) From: Linus Torvalds To: Andrew Morton cc: Jamie Lokier , olof@austin.ibm.com, linux-kernel@vger.kernel.org, rusty@rustcorp.com.au Subject: Re: [PATCH/RFC] Futex mmap_sem deadlock In-Reply-To: <20050222134010.4c286e64.akpm@osdl.org> Message-ID: References: <20050222190646.GA7079@austin.ibm.com> <20050222115503.729cd17b.akpm@osdl.org> <20050222210752.GG22555@mail.shareable.org> <20050222134010.4c286e64.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 22 Feb 2005, Andrew Morton wrote: > > However the pte can get unmapped by memory reclaim so we could still take a > minor fault, and hit the same deadlock, yes? You _could_ fix that by getting the pagetable spinlock, I guess. Which check_user_page_readable() assumes you'd be holding anyway (not holding it would appear to be a bug). At which point you might as well just walk the tables by hand and just do the read that way. Of course, then you have virtual aliasing issues etc. Insane, but possible. Linus