Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 31 Jul 2018 11:12:48 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Rik van Riel <riel@surriel.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel-team <kernel-team@fb.com>, X86 ML <x86@kernel.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Ingo Molnar <mingo@kernel.org>, Mike Galbraith <efault@gmx.de>,
        Dave Hansen <dave.hansen@intel.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v2 11/11] mm,sched: conditionally skip lazy TLB mm
 refcounting
Message-ID: <20180731091248.GS2494@hirez.programming.kicks-ass.net>
References: <20180728215357.3249-1-riel@surriel.com>
 <20180728215357.3249-11-riel@surriel.com>
 <CALCETrWS4pE5Tv3OErM3AD-E=CGG3U+2CBVecRF3N0c+g42vEg@mail.gmail.com>
 <20180729155452.37eddc11@imladris.surriel.com>
 <20180730095502.GG2494@hirez.programming.kicks-ass.net>
 <1532961011.28585.30.camel@surriel.com>
 <20180730162653.GM2494@hirez.programming.kicks-ass.net>
 <1532999155.28585.56.camel@surriel.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="nbjgUHX6eyHhY7pW"
Content-Disposition: inline
In-Reply-To: <1532999155.28585.56.camel@surriel.com>
User-Agent: Mutt/1.10.0 (2018-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


--nbjgUHX6eyHhY7pW
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Mon, Jul 30, 2018 at 09:05:55PM -0400, Rik van Riel wrote:
> On Mon, 2018-07-30 at 18:26 +0200, Peter Zijlstra wrote:
> >=20
> > So for ARCH_NO_ACTIVE_MM we never touch ->active_mm and therefore
> > ->active_mm =3D=3D ->mm.
>=20
> Close, but not true for kernel threads, which have a=20
> NULL ->mm, but a non-null ->active_mm that gets passed
> to enter_lazy_tlb().

I'm confused on the need for this. We mark the CPU lazy, why do we still
care about this?

--nbjgUHX6eyHhY7pW
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=3wx1
-----END PGP SIGNATURE-----

--nbjgUHX6eyHhY7pW--