linux-kernel - Re: [PATCH] x86,mm: print likely CPU at segfault time

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Message-ID: <a9f568139f0bd82cc8460c2c4f831f03a74f2a89.camel@surriel.com>
Date:   Mon, 19 Jul 2021 15:34:38 -0400
From:   Rik van Riel <riel@...riel.com>
To:     Dave Hansen <dave.hansen@...el.com>, linux-kernel@...r.kernel.org
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>, kernel-team@...com,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time

On Mon, 2021-07-19 at 12:20 -0700, Dave Hansen wrote:

> If it's as trivial as:
> 
>         printk(KERN_CONT " on cpu/core %d/%d",
>                 raw_smp_processor_id(),
>                 topology_core_id(raw_smp_processor_id()));
> 
> 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
> enabled.

One problem with topology_core_id() is that that, on a
multi-socket system, the core number may not be unique.

That is why I ended up going with just the CPU number.
It's pretty easy to put one and one together afterwards.

Thanks for your quick patch review.

-- 
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