Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <a9f568139f0bd82cc8460c2c4f831f03a74f2a89.camel@surriel.com>
Subject: Re: [PATCH] x86,mm: print likely CPU at segfault time
From:   Rik van Riel <riel@surriel.com>
To:     Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org
Cc:     Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>, kernel-team@fb.com,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org
Date:   Mon, 19 Jul 2021 15:34:38 -0400
In-Reply-To: <c8e023cb-6f50-36f5-65d4-c5e25b264029@intel.com>
References: <20210719150041.3c719c94@imladris.surriel.com>
         <c8e023cb-6f50-36f5-65d4-c5e25b264029@intel.com>
Content-Type: multipart/signed; micalg="pgp-sha256";
        protocol="application/pgp-signature"; boundary="=-l5bQu8+DJCBx325/Mnpg"
User-Agent: Evolution 3.40.2 (3.40.2-1.fc34) 
MIME-Version: 1.0
Sender: riel@shelob.surriel.com
Precedence: bulk


--=-l5bQu8+DJCBx325/Mnpg
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

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

> If it's as trivial as:
>=20
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0printk(KERN_CONT " on cpu=
/core %d/%d",
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0raw_smp_processor_id(),
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0topology_core_id(raw_smp_processor_id()));
>=20
> it would be handy.=C2=A0 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.

--=20
All Rights Reversed.

--=-l5bQu8+DJCBx325/Mnpg
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part
Content-Transfer-Encoding: 7bit

-----BEGIN PGP SIGNATURE-----

iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAmD1084ACgkQznnekoTE
3oMZwQf/dqGU0jn2GOBPnw0rMkRskRrmxg0yleYt5P2UKFatS3hTKRNCQVBg10pL
5BA6gsz2yk/oSHc/188BCjcW8KcWdq21obf9oxflp0w1uGkP8A9CGIg1zt0VndA2
zO2W18o6tECPgxYEevpaVlqqHI+yLV7XNN4Wk//UF5T1M2+QBr4BBvoPq9SVKp6w
3kbE1smSvgTz2FmPS6LrbJkvZSkc/e30veMn8py1q6NHDZe/b5wVbgcQJwEAdU1S
8eIiJnZ3VSQnRd/ay5kYrsYcm95T5rxjoTsBvIBy6FTBIiJXCy01kMff3/sicr5e
xgBsiYv058s3wwzNquscFsBdQH7r0Q==
=Ppt7
-----END PGP SIGNATURE-----

--=-l5bQu8+DJCBx325/Mnpg--