Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753174AbZDUOyZ (ORCPT ); Tue, 21 Apr 2009 10:54:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751442AbZDUOyQ (ORCPT ); Tue, 21 Apr 2009 10:54:16 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:35049 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbZDUOyP (ORCPT ); Tue, 21 Apr 2009 10:54:15 -0400 Date: Tue, 21 Apr 2009 10:54:13 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Ingo Molnar cc: Peter Zijlstra , =?ISO-8859-15?Q?Fr=E9d=E9ric_Weisbecker?= , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH][GIT PULL] ring-buffer: only warn on wrap if buffer is bigger than two pages In-Reply-To: <20090421143509.GA5243@elte.hu> Message-ID: References: <20090420222257.267399830@goodmis.org> <20090421082354.GC12512@elte.hu> <20090421094616.GA14561@elte.hu> <20090421143509.GA5243@elte.hu> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) 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 Content-Length: 2811 Lines: 80 On Tue, 21 Apr 2009, Ingo Molnar wrote: > > here's a new one: > > Testing event sched_kthread_stop: <4>------------[ cut here ]------------ > WARNING: at kernel/fork.c:988 copy_process+0x147/0xf7d() > Modules linked in: > > config attached, bootlog below. This warning has the signs of some > sort of lockdep interaction. (this too is a new one - it never > triggered before) > > Ingo > > Running tests again, along with the function tracer > Running tests on trace events: > Testing event kfree_skb: OK > Testing event kmalloc: OK > Testing event kmem_cache_alloc: OK > Testing event kmalloc_node: OK > Testing event kmem_cache_alloc_node: OK > Testing event kfree: OK > Testing event kmem_cache_free: OK > Testing event irq_handler_exit: OK > Testing event irq_handler_entry: OK > Testing event softirq_entry: OK > Testing event softirq_exit: OK > Testing event lock_acquired: OK > Testing event lock_acquire: OK > Testing event lock_release: OK > Testing event lock_contended: OK > Testing event sched_kthread_stop: <4>------------[ cut here ]------------ > WARNING: at kernel/fork.c:988 copy_process+0x147/0xf7d() > Modules linked in: > Pid: 2, comm: kthreadd Not tainted 2.6.30-rc2-tip-01581-gf4879a9-dirty #34509 > Call Trace: > [] warn_slowpath+0x96/0xca > [] ? trace_hardirqs_on_caller+0xff/0x14c > [] ? trace_hardirqs_on+0xd/0xf > [] ? __mutex_init+0x5a/0x64 > [] ? perf_counter_init_task+0x65/0x17b > [] copy_process+0x147/0xf7d > [] ? trace+0x3a/0x73 > [] do_fork+0x19f/0x478 > [] ? kthreadd+0xb8/0x11c > [] kernel_thread+0x82/0xe0 > [] ? schedule+0x11f/0x5e1 > [] ? kthread+0x0/0x80 > [] ? child_rip+0x0/0x20 > [] ? kthreadd+0xcc/0x11c > [] ? early_idt_handler+0x0/0x71 > [] child_rip+0xa/0x20 > [] ? restore_args+0x0/0x30 > [] ? kthreadd+0x0/0x11c > [] ? child_rip+0x0/0x20 > ---[ end trace 0843ba422c5d704e ]--- > OK > Testing event sched_kthread_stop_ret: OK The above looks like the tracer slowed things down enough to trigger a race elsewhere. We have function tracing happening, and here we enabled the sched_kthread_stop tracepoint. Each test starts and stops a kernel thread. I'm not sure how this could have triggered. I'll investigate a little more. -- Steve -- 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/