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From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Jens Axboe <axboe@kernel.dk>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	acme@kernel.org
Cc: linux-perf-users@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	Kim Phillips <kim.phillips@amd.com>
Subject: Re: NMI reason 2d when running perf
Date: Mon, 20 Mar 2023 10:14:51 +0530	[thread overview]
Message-ID: <e08e33d5-4f6d-91aa-f335-9404d16a983c@amd.com> (raw)
In-Reply-To: <25fccb43-8338-a690-0009-384dc0640169@kernel.dk>

On 17-Mar-23 7:55 PM, Jens Axboe 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.

Are you using IBS directly or indirectly (perf record, if run as root
without explicit -e event, internally invokes IBS)? fwiw, Zen2 had
similar hw issue where IBS can raise NMI without sample valid bit set
while exiting from CC6 state[1]. But as per my knowledge, it's already
fixed in Zen3.

[1]: https://lore.kernel.org/all/YFDSSxftYw9tCGC6@krava/

> 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:
> 
> commit 6015b1aca1a233379625385feb01dd014aca60b5 (origin/master, origin/HEAD)
> Author: Linus Torvalds <torvalds@linux-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.
> 


      parent reply	other threads:[~2023-03-20  4:45 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-17 14:25 NMI reason 2d when running perf Jens Axboe
2023-03-18 14:44 ` Dr. David Alan Gilbert
2023-03-20  4:44 ` Ravi Bangoria [this message]

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