From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754594AbYCML1B (ORCPT ); Thu, 13 Mar 2008 07:27:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752421AbYCML0x (ORCPT ); Thu, 13 Mar 2008 07:26:53 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:38556 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752396AbYCML0w (ORCPT ); Thu, 13 Mar 2008 07:26:52 -0400 Date: Thu, 13 Mar 2008 11:25:28 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Peter Zijlstra cc: linux-kernel@vger.kernel.org, Ingo Molnar , Gautham R Shenoy Subject: Re: [PATCH 0/2] lockdep vs recursive read locks In-Reply-To: <20080312120920.929901000@chello.nl> Message-ID: References: <20080312120920.929901000@chello.nl> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Mar 2008, Peter Zijlstra wrote: > We seemed to have some lockdep trouble wrt recursive read locks. Today Gautham > asked me some specific questions about it, which led to these patches. > > IIRC Hugh ran into something similar a while back. This hopefully fixes it. Hmm, I don't remember that myself: can you jog my memory? What I do remember is that when I fixed madvise(MADV_REMOVE i.e. holepunch) not to hold mmap_sem (at that time down_write but today down_read, though would still be bad) across vmtruncate_range which takes i_mutex (contrast writing from an unfaulted area that takes i_mutex then down_read mmap_sem), Ingo asked me offline if lockdep caught that and it didn't. Just tried again now, with your patches applied, and madvise_remove restored to its old misbehaviour, and it looks like lockdep still doesn't catch it (but suspect me of pilot error if you find otherwise). Hugh