Messages in this thread | | | From | Song Liu <> | Subject | Re: WARNING with LBR + precise_ip=2 + bpf_get_stackid() | Date | Thu, 18 Jun 2020 20:18:06 +0000 |
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> On Jun 18, 2020, at 11:33 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > On Thu, Jun 18, 2020 at 05:25:24PM +0000, Song Liu wrote: >
[...]
>> 0xfffffe00004d1380 __start_orc_unwind >> 0xfffffe00004d1388 unwind_next_frame.cold.7 >> 0xfffffe00004d13c8 perf_callchain_kernel >> 0xfffffe00004d1418 entry_SYSCALL_64 >> 0xfffffe00004d1450 get_perf_callchain >> 0xfffffe00004d14b0 bpf_get_stack > > This, this is where it gets buggerd. This is a BPF problem, not a perf > problem. > > You'll note that if you ask perf for a PERF_SAMPLE_CALLCHAIN we'll do > that early in setup_pebs_fixed_sample_data().
We did notice perf works fine in similar scenario. I guess need similar logic in BPF.
Thanks, Song
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