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From:   Qian Cai <cai@lca.pw>
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Date:   Tue, 21 Jan 2020 10:50:56 -0500
Subject: Re: [PATCH -next] x86/mm/pat: silence a data race in cpa_4k_install
Message-Id: <388BB7AF-C7AB-4F0D-B79A-A43097C12E62@lca.pw>
Cc:     Marco Elver <elver@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
To:     Borislav Petkov <bp@alien8.de>
Sender: linux-kernel-owner@vger.kernel.org
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> On Jan 21, 2020, at 10:45 AM, Borislav Petkov <bp@alien8.de> wrote:
>=20
> Perhaps because you've been dealing with KCSAN for so long. :-)
>=20
> The main angle here, IMO, is that this "fix" is being done solely for
> KCSAN. Or is there another reason to "fix" intentional data races? At
> least I don't see one. And the text says
>=20
> "This will generate a lot of noise on a debug kernel with
> debug_pagealloc with KCSAN enabled which could render the system
> unusable."
>=20
> So yes, I think it should say something about making KCSAN happy.
>=20
> Oh, and while at it I'd prefer it if it did the __no_kcsan function
> annotation instead of the data_race() thing.

Or the patch title could be =E2=80=9Cplay KCSAN well with debug_pagealloc=E2=
=80=9D?

I am fine with __no_kcsan as well. I just need to retest the whole thing fir=
st.=