From: Rik van Riel <riel@surriel.com>
To: Matt Fleming <matt@readmodwrite.com>
Cc: "Henrik Böving" <henrik@lean-fro.org>,
dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, linux-kernel@vger.kernel.org,
"Sebastian Ullrich" <sebastian@lean-fro.org>,
"Joscha Mennicken" <joscha@lean-fro.org>,
kernel-team@cloudflare.com
Subject: Re: PROBLEM: Probabilistic segfault on AMD hardware with INVLPGB
Date: Tue, 07 Jul 2026 10:11:43 -0400 [thread overview]
Message-ID: <1e4ab5c5f64b3bddc0773cf305708500abc66999.camel@surriel.com> (raw)
In-Reply-To: <akzuETUv5XEFSRL6@matt-Precision-5490>
On Tue, 2026-07-07 at 13:18 +0100, Matt Fleming wrote:
> Hi Rik and Henrik,
>
> I've got a small C reproducer that triggers this within the first
> round
> on Cloudflare's AMD Turin machines:
>
> https://gist.github.com/mfleming/ca26ad3f8d65a12d23d62fb176480fc1
>
> Build:
>
> gcc -O2 -Wall -Wextra -pthread -static -o repro-invlpgb repro-
> invlpgb.c
>
> Run:
>
> ./repro-invlpgb --batch --rounds 20 --jobs 32 -d 5 -w 8 -m 2 -s 512
> -q
>
Now that's interesting. I ran it for 100 rounds on
a 158 core Turin system, without hitting the issue.
I'll play around with it some more to see whether
I can make it happen by varying the parameters,
but now I'm also wondering whether hardware
differences might be at play.
--
All Rights Reversed.
next prev parent reply other threads:[~2026-07-07 14:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-19 13:17 Henrik Böving
2026-06-22 19:00 ` Rik van Riel
2026-06-23 12:28 ` Henrik Böving
2026-06-23 13:47 ` Andrew Cooper
2026-06-23 15:59 ` Rik van Riel
2026-07-07 12:18 ` Matt Fleming
2026-07-07 13:45 ` Henrik Böving
2026-07-07 14:11 ` Rik van Riel [this message]
2026-07-08 14:51 ` Dave Hansen
2026-07-07 16:44 ` Rik van Riel
2026-07-08 15:27 ` Rik van Riel
2026-07-08 15:51 ` Borislav Petkov
2026-07-08 16:17 ` Borislav Petkov
2026-07-09 7:21 ` Matt Fleming
2026-07-09 19:17 ` Borislav Petkov
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