Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752452AbaLFWPG (ORCPT ); Sat, 6 Dec 2014 17:15:06 -0500 Received: from www.linutronix.de ([62.245.132.108]:39108 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167AbaLFWPE (ORCPT ); Sat, 6 Dec 2014 17:15:04 -0500 Date: Sat, 6 Dec 2014 23:14:41 +0100 (CET) From: Thomas Gleixner To: Chuck Ebbert cc: Dave Jones , Linus Torvalds , Chris Mason , Mike Galbraith , Ingo Molnar , Peter Zijlstra , =?ISO-8859-15?Q?D=E2niel_Fraga?= , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 In-Reply-To: <20141206043719.66a1aec6@as> Message-ID: References: <547ccf74.a5198c0a.25de.26d9@mx.google.com> <20141201230339.GA20487@ret.masoncoding.com> <1417529606.3924.26.camel@maggy.simpson.net> <1417540493.21136.3@mail.thefacebook.com> <20141203184111.GA32005@redhat.com> <20141205171501.GA1320@redhat.com> <20141205184808.GA2753@redhat.com> <20141206043719.66a1aec6@as> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 6 Dec 2014, Chuck Ebbert wrote: > On Fri, 5 Dec 2014 13:48:08 -0500 > Dave Jones wrote: > > > [ 1611.749570] [] do_nmi+0xb8/0xf0 > > [ 1611.750438] [] end_repeat_nmi+0x1e/0x2e > > [ 1611.751312] [] ? preempt_count_add+0x18/0xb0 > > [ 1611.752177] [] ? preempt_count_add+0x18/0xb0 > > [ 1611.753025] [] ? preempt_count_add+0x18/0xb0 > > [ 1611.753861] <> [] is_module_text_address+0x17/0x50 > > [ 1611.754734] [] __kernel_text_address+0x58/0x80 > > [ 1611.755575] [] print_context_stack+0x8f/0x100 > > [ 1611.756410] [] dump_trace+0x140/0x370 > > [ 1611.757242] [] ? getname_flags+0x4f/0x1a0 > > [ 1611.758072] [] ? getname_flags+0x4f/0x1a0 > > [ 1611.758895] [] save_stack_trace+0x2b/0x50 > > [ 1611.759720] [] set_track+0x70/0x140 > > [ 1611.760541] [] alloc_debug_processing+0x92/0x118 > > [ 1611.761366] [] __slab_alloc+0x45f/0x56f > > [ 1611.762195] [] ? getname_flags+0x4f/0x1a0 > > [ 1611.763024] [] ? __slab_free+0x114/0x309 > > [ 1611.763853] [] ? debug_check_no_obj_freed+0x17e/0x270 > > [ 1611.764712] [] ? getname_flags+0x4f/0x1a0 > > [ 1611.765539] [] kmem_cache_alloc+0x1f6/0x270 > > So, every time there is a slab allocation the entire stack trace gets > saved as human readable text. And for each line in the trace, Wrong. It gets saved as address. No conversion to text at all. > is_module_text_address() can be called, which has huge overhead > walking the entire list of loaded modules. No wonder there are > timeouts... You would have to have a gazillion of modules to make that overhead big enough to trigger a multi seconds watchdog. Thanks, tglx -- 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/