Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763999AbZFPU5H (ORCPT ); Tue, 16 Jun 2009 16:57:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763719AbZFPU4y (ORCPT ); Tue, 16 Jun 2009 16:56:54 -0400 Received: from yw-out-2122.google.com ([74.125.46.25]:53985 "EHLO yw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763796AbZFPU4w convert rfc822-to-8bit (ORCPT ); Tue, 16 Jun 2009 16:56:52 -0400 MIME-Version: 1.0 Date: Tue, 16 Jun 2009 13:56:54 -0700 (PDT) In-Reply-To: X-IP: 86.25.246.25 References:

User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 Gecko/2008061017 Firefox/3.0,gzip(gfe),gzip(gfe) X-HTTP-Via: 1.1 home (squid/3.0.STABLE8) Message-ID: <677c7cd8-4cdf-49be-a72d-67d2c381b4eb@l12g2000yqo.googlegroups.com> Subject: Re: lockdep warning: module_mutex vs. ftrace_lock From: Daniel J Blueman To: Steven Rostedt Cc: Linux Kernel Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2920 Lines: 63 On Apr 13, 3:10?pm, Steven Rostedt wrote: > On Tue, 2009-04-07 at 20:30 +0200, Frederic Weisbecker wrote: > > On Tue, Apr 07, 2009 at 06:34:56PM +0200, Miklos Szeredi wrote: > > > ======================================================= > > > [ INFO: possible circular locking dependency detected ] > > > 2.6.29-09854-gd508afb-dirty #6 > > > ------------------------------------------------------- > > > modprobe/3184 is trying to acquire lock: > > > ?(ftrace_lock){+.+.+.}, at: [] ftrace_convert_nops+0x32/0x267 > > > > but task is already holding lock: > > > ?(module_mutex){+.+.+.}, at: [] sys_init_module+0x3f/0x1d3 > > > > which lock already depends on the new lock. > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (module_mutex){+.+.+.}: > > > ? ? ? ?[] __lock_acquire+0x12fe/0x1668 > > > ? ? ? ?[] lock_acquire+0xee/0x112 > > > ? ? ? ?[] mutex_lock_nested+0x4f/0x305 > > > ? ? ? ?[] module_update_tracepoints+0x1c/0x73 > > > ? ? ? ?[] tracepoint_update_probes+0x21/0x23 > > > ? ? ? ?[] tracepoint_probe_register+0x4a/0x68 > > > ? ? ? ?[] register_ftrace_graph+0x2a9/0x30f > > > ? ? ? ?[] trace_selftest_startup_function_graph+0x2e/0xbb > > > ? ? ? ?[] register_tracer+0x151/0x26e > > > ? ? ? ?[] init_graph_trace+0x10/0x12 > > > ? ? ? ?[] do_one_initcall+0x5b/0x135 > > > ? ? ? ?[] kernel_init+0x12f/0x185 > > > ? ? ? ?[] child_rip+0xa/0x20 > > > ? ? ? ?[] 0xffffffffffffffff > > > > -> #0 (ftrace_lock){+.+.+.}: > > > ? ? ? ?[] __lock_acquire+0x101b/0x1668 > > > ? ? ? ?[] lock_acquire+0xee/0x112 > > > ? ? ? ?[] mutex_lock_nested+0x4f/0x305 > > > ? ? ? ?[] ftrace_convert_nops+0x32/0x267 > > > ? ? ? ?[] ftrace_init_module+0x17/0x19 > > > ? ? ? ?[] load_module+0x1122/0x160b > > > ? ? ? ?[] sys_init_module+0x5c/0x1d3 > > > ? ? ? ?[] system_call_fastpath+0x16/0x1b > > > ? ? ? ?[] 0xffffffffffffffff > > > Ah that's this ftrace/modules lock dependency that Steven told me about > > recently. Steven, do you know more about it now? > > Yeah, I think I submitted a patch to fix that. I'll check my repo. This is still live in 2.6.30 proper. Let me know if you'd like further testing on your patch, or if you can't find locate it. Thanks, Daniel -- Daniel J Blueman -- 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/