LKML Archive on
help / color / mirror / Atom feed
From: Dave Hansen <>
To: Rik van Riel <>,
Cc: Dave Hansen <>,
	Andy Lutomirski <>,, Peter Zijlstra <>,
	Ingo Molnar <>, Borislav Petkov <>,
Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time
Date: Mon, 19 Jul 2021 12:20:24 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 7/19/21 12:00 PM, Rik van Riel wrote:
> In a large enough fleet of computers, it is common to have a few bad
> CPUs. Those can often be identified by seeing that some commonly run
> kernel code (that runs fine everywhere else) keeps crashing on the
> same CPU core on a particular bad system.

I've encountered a few of these kinds of things over the years.  This is
*definitely* useful.  What you've proposed here is surely the simplest
thing we could print and probably also offers the best bang for our buck.

The only other thing I thought of is that it might be nice to print out
the core id instead of the CPU id.  If there are hardware issues with a
CPU, they're likely to affect both threads.  Seeing to different "CPUs"
in an SMT environment might tempt some folks to think it's not a
core-level hardware issue.

If it's as trivial as:

	printk(KERN_CONT " on cpu/core %d/%d",

it would be handy.  But, it's also not hard to look at 10 segfaults, see
that they happened only on 2 CPUs and realize that hyperthreading is

Either way, this patch moves things in the right direction, so:

Acked-by: Dave Hansen <>

  reply	other threads:[~2021-07-19 19:59 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 19:00 Rik van Riel
2021-07-19 19:20 ` Dave Hansen [this message]
2021-07-19 19:34   ` Rik van Riel
2021-07-21 20:38     ` Thomas Gleixner
2021-07-21 20:36 ` Thomas Gleixner
2021-07-24  1:38   ` Rik van Riel
2022-08-02 20:09 Rik van Riel
2022-08-03 14:49 ` Dave Hansen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \
    --subject='Re: [PATCH] x86,mm: print likely CPU at segfault time' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).