Messages in this thread | | | Date | Fri, 12 Jun 2015 16:33:17 +0200 | From | Daniel Wagner <> | Subject | Re: latency histogram with BPF |
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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
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