linux-kernel - Re: NMI reason 2d when running perf

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Message-ID: <ZBXOPvIqybwtihJY@gallifrey>
Date:   Sat, 18 Mar 2023 14:44:14 +0000
From:   "Dr. David Alan Gilbert" <linux@...blig.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, acme@...nel.org,
        linux-perf-users@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: NMI reason 2d when running perf

* Jens Axboe (axboe@...nel.dk) wrote:
> Hi,
> 
> When running perf on my Dell R7525 on a running process, I get a ton of:
> 
> [  504.234782] Dazed and confused, but trying to continue
> [  504.267843] Uhhuh. NMI received for unknown reason 2d on CPU 48.
> [  504.267846] Dazed and confused, but trying to continue
> [  504.335975] Uhhuh. NMI received for unknown reason 2d on CPU 48.
> [  504.335977] Dazed and confused, but trying to continue
> [  504.368031] Uhhuh. NMI received for unknown reason 2d on CPU 48.
> [  504.368033] Dazed and confused, but trying to continue
> [  504.371037] Uhhuh. NMI received for unknown reason 2d on CPU 48.
> [  504.371038] Dazed and confused, but trying to continue
> [  504.439165] Uhhuh. NMI received for unknown reason 2d on CPU 48.
> [  504.439167] Dazed and confused, but trying to continue
> 
> spew in dmesg. The box has 2x7763 CPUS. This seems to be a recent
> regression, been using this box for a while and haven't seen this
> before. The test being traced is pinned to CPU 48. The box is currently
> running:

I'm not sure this is new; I've seen this intermittently on AMD boxes
for a few years. Always when running perf or related tools.

Dave

> commit 6015b1aca1a233379625385feb01dd014aca60b5 (origin/master, origin/HEAD)
> Author: Linus Torvalds <torvalds@...ux-foundation.org>
> Date:   Tue Mar 14 19:32:38 2023 -0700
> 
>     sched_getaffinity: don't assume 'cpumask_size()' is fully initialized
> 
> with the pending block/io_uring branches merged in for testing.
> 
> -- 
> Jens Axboe
> 
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
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