Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261250AbVBVVUU (ORCPT ); Tue, 22 Feb 2005 16:20:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261255AbVBVVUU (ORCPT ); Tue, 22 Feb 2005 16:20:20 -0500 Received: from gate.crashing.org ([63.228.1.57]:10975 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S261250AbVBVVUO (ORCPT ); Tue, 22 Feb 2005 16:20:14 -0500 Subject: Re: [PATCH/RFC] Futex mmap_sem deadlock From: Benjamin Herrenschmidt To: Linus Torvalds Cc: Olof Johansson , Kernel Mailing List , Andrew Morton , jamie@shareable.org, Rusty Russell , David Howells In-Reply-To: <1109106969.5412.138.camel@gaston> References: <20050222190646.GA7079@austin.ibm.com> <1109106969.5412.138.camel@gaston> Content-Type: text/plain Date: Wed, 23 Feb 2005 08:19:20 +1100 Message-Id: <1109107160.5326.140.camel@gaston> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 787 Lines: 21 On Wed, 2005-02-23 at 08:16 +1100, Benjamin Herrenschmidt wrote: > On Tue, 2005-02-22 at 11:36 -0800, Linus Torvalds wrote: > > > DavidH - what's the word on nested read-semaphores like this? Are they > > supposed to work (like nested read-spinlocks), or do we need to do the > > things Olof does? > > Isn't Olof scheme racy ? Can't the stuff get swapped out between the > first get_user() and the "real" one ? Forget it, I missed the check_user_page_readable() guy within the semaphore protection. I didn't know that function ;) Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/