linux-kernel - Re: [RFC v2] perf: Rewrite core context handling

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Message-ID: <5e69c472-b9d4-3813-70a4-f0d8bbaa14d3@amd.com>
Date:   Mon, 29 Aug 2022 09:24:55 +0530
From:   Ravi Bangoria <ravi.bangoria@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     acme@...nel.org, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org, songliubraving@...com,
        eranian@...gle.com, alexey.budankov@...ux.intel.com,
        ak@...ux.intel.com, mark.rutland@....com, megha.dey@...el.com,
        frederic@...nel.org, maddy@...ux.ibm.com, irogers@...gle.com,
        kim.phillips@....com, linux-kernel@...r.kernel.org,
        santosh.shukla@....com, Sandipan Das <sandipan.das@....com>,
        ravi.bangoria@....com
Subject: Re: [RFC v2] perf: Rewrite core context handling

On 23-Aug-22 9:50 AM, Ravi Bangoria wrote:
> 
>> With this, I can run 'perf test' and perf_event_tests without any error in
>> dmesg. I'll run perf fuzzer over night and see if it reports any issue.
> 
> I hit kernel crash with fuzzer. I'm yet to debug it. Here is the trace:
> 
>   BUG: kernel NULL pointer dereference, address: 0000000000000198
>   #PF: supervisor read access in kernel mode
>   #PF: error_code(0x0000) - not-present page
>   PGD 0 P4D 0
>   Oops: 0000 [#1] PREEMPT SMP NOPTI
>   CPU: 48 PID: 0 Comm: swapper/48 Not tainted 6.0.0-rc1-perf-event-context-peter-queue+ #153
>   Hardware name: Dell Inc. PowerEdge R6515/07PXPY, BIOS 2.7.3 03/31/2022
>   RIP: 0010:x86_pmu_enable_event+0x3c/0x120

I was able to reproduce this with vanilla v6.0-rc2 kernel.

Thanks,
Ravi