From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756640Ab1K3Idi (ORCPT ); Wed, 30 Nov 2011 03:33:38 -0500 Received: from mail-yx0-f174.google.com ([209.85.213.174]:56219 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751774Ab1K3Idf (ORCPT ); Wed, 30 Nov 2011 03:33:35 -0500 Date: Wed, 30 Nov 2011 16:33:24 +0800 From: Yong Zhang To: John Kacur Cc: Peter Zijlstra , Thomas Gleixner , Clark Williams , RT , LKML Subject: Re: lockdep splat with 3.2-rc2-rt3+ Message-ID: <20111130083324.GA1632@zhy> Reply-To: Yong Zhang References: <20111120113621.7d738d55@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 24, 2011 at 11:50:06PM +0100, John Kacur wrote: > So, as a little experiment, on v3.2.0-rc2-rt3 > I redefined MAX_LOCKDEP_ENTRIES from 16384UL to 32768UL > > Then from /proc/lockdep_stats > > I got > direct dependencies: 18026 [max: 32768] > > The fact that 18026 is only a little larger than the normal max (by 1642) > to me is another indication that, this is not a case of something in > lockdep going out of control that needs to be fixed, but just another > indication that in some circumstances it would be legitimate to raise > the value. Yeah, seems the reason is in RT we have no dedicated softirq-context anymore, IOW, both process-context and softirq-context are taken as process-context. That will increase the usage of lockdep entries because we expand the scope of process-context. Thanks, Yong