Messages in this thread | | | Date | Mon, 7 Nov 2022 15:59:47 +0530 | Subject | Re: Perf: BUG: kernel NULL pointer dereference, address: 0000000000000198 | From | Ravi Bangoria <> |
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On 03-Nov-22 9:42 PM, Ravi Bangoria wrote: > On 03-Nov-22 6:03 PM, Peter Zijlstra wrote: >> On Thu, Nov 03, 2022 at 05:15:30PM +0530, Ravi Bangoria wrote: >> >>> Sorry was distracted a bit. So, this seems to be happening because of >>> race between amd_pmu_enable_all() and perf event NMI. Something like: >>> >>> amd_pmu_enable_all() >>> { >>> if (!test_bit(idx, cpuc->active_mask)) >>> >>> --->/* perf NMI entry */ >>> ... >>> x86_pmu_stop() { >>> __clear_bit(hwc->idx, cpuc->active_mask); >>> cpuc->events[hwc->idx] = NULL; >>> } >>> ... >>> <---/* perf NMI exit */ >>> >>> amd_pmu_enable_event(cpuc->events[idx]); >>> } >> >> Hmm, do you have more information? > > I've extracted function graph logs from crash dump and uploaded it here: > https://github.com/BangoriaRavi/function_graph/blob/main/trace.function_graph.dat > > crash was on CPU1.
git bisect let me to a BRS patch:
commit ada543459cab7f653dcacdaba4011a8bb19c627c Author: Stephane Eranian <eranian@google.com> Date: Tue Mar 22 15:15:07 2022 -0700
perf/x86/amd: Add AMD Fam19h Branch Sampling support
Add support for the AMD Fam19h 16-deep branch sampling feature as described in the AMD PPR Fam19h Model 01h Revision B1. This is a model specific extension. It is not an architected AMD feature.
Thanks, Ravi
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