Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755382AbbFLOdf (ORCPT ); Fri, 12 Jun 2015 10:33:35 -0400 Received: from mail.bmw-carit.de ([62.245.222.98]:34279 "EHLO mail.bmw-carit.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753458AbbFLOdc (ORCPT ); Fri, 12 Jun 2015 10:33:32 -0400 X-CTCH-RefID: str=0001.0A0C0202.557AEDAF.0036,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 Message-ID: <557AEDAD.2060507@bmw-carit.de> Date: Fri, 12 Jun 2015 16:33:17 +0200 From: Daniel Wagner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Daniel Wagner , Alexei Starovoitov , Steven Rostedt , Tom Zanussi CC: "linux-kernel@vger.kernel.org" , Wang Nan Subject: Re: latency histogram with BPF References: <557937D8.90606@bmw-carit.de> <557A06D7.7030304@plumgrid.com> <557A783C.5080803@bmw-carit.de> In-Reply-To: <557A783C.5080803@bmw-carit.de> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1245 Lines: 33 On 06/12/2015 08:12 AM, Daniel Wagner wrote: > On 06/12/2015 12:08 AM, Alexei Starovoitov wrote: >> On 6/11/15 12:25 AM, Daniel Wagner wrote: >> If you have any suggestions on where to look, I'm all ears. >> My stack traces look like: >> Running with 10*40 (== 400) tasks. >> [ 12.032571] kernel BUG at ../mm/slub.c:3413! I hit this as well. After looking and playing around for while I think I found the source of the problem: The path from the BPF program into the hash table code is triggering the crash. Attaching kprobes to trace_preempt_[on|off] works fine. Empty BPF programs connected to the probes is no problem as well. So I changed the BPF program to use only arrays instead of hash tables. No crash anymore. Thanks Steven for the tip :) I suspect the hash table code will call trace_preempt_[off|on] eventually and that is not going to fly. The program is still in a rough state. I'll send an cleanup version next week. (My brain is melting down, too hot here...) cheers, daniel -- 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/