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Date: Fri, 12 Jun 2015 16:33:17 +0200 From: Daniel Wagner <daniel.wagner@...-carit.de> To: Daniel Wagner <daniel.wagner@...-carit.de>, Alexei Starovoitov <ast@...mgrid.com>, Steven Rostedt <rostedt@...dmis.org>, Tom Zanussi <tom.zanussi@...ux.intel.com> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Wang Nan <wangnan0@...wei.com> Subject: Re: latency histogram with BPF 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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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