From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261491AbUCSCmE (ORCPT ); Thu, 18 Mar 2004 21:42:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261627AbUCSCmE (ORCPT ); Thu, 18 Mar 2004 21:42:04 -0500 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:32391 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S261491AbUCSCmB (ORCPT ); Thu, 18 Mar 2004 21:42:01 -0500 Date: Fri, 19 Mar 2004 03:42:51 +0100 From: Andrea Arcangeli To: Hugh Dickins Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] anobjrmap 1/6 objrmap Message-ID: <20040319024251.GA31498@dualathlon.random> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 18, 2004 at 11:21:07PM +0000, Hugh Dickins wrote: > + if (!spin_trylock(&mm->page_table_lock)) > + return 1; > + [..] > + if (down_trylock(&mapping->i_shared_sem)) > + return 1; > + those two will hang your kernel in the workload I posted to the list a few days ago. With previous kernels the above didn't matter, but starting with 2.6.5-rc1 it does matter, if we cannot know if it's referenced or not, we must assume it's not and return 0 or it lives locks hard with all tasks stuck and one must click reboot. I recommend you to share my objrmap patch, the objrmap should be exactly the same for both of us. It took me a while to figure out the above issue and fix it in the objrmap patch, since it was hard to assume a change in 2.6.5-rc1 broke objrmap (there were no rejects and objrmap was pretty much unchanged since the 2.5.x days for an year).