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Date:   Mon, 14 Dec 2020 15:53:40 +1000
From:   Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH 2/8] x86: use exit_lazy_tlb rather than
 membarrier_mm_sync_core_before_usermode
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Anton Blanchard <anton@ozlabs.org>, Arnd Bergmann <arnd@arndb.de>,
        linux-arch <linux-arch@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Peter Zijlstra <peterz@infradead.org>, X86 ML <x86@kernel.org>
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Excerpts from Nicholas Piggin's message of December 14, 2020 2:07 pm:
> Excerpts from Andy Lutomirski's message of December 11, 2020 10:11 am:
>>> On Dec 5, 2020, at 7:59 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
>>>
>>=20
>>> I'm still going to persue shoot-lazies for the merge window. As you
>>> see it's about a dozen lines and a if (IS_ENABLED(... in core code.
>>> Your change is common code, but a significant complexity (which
>>> affects all archs) so needs a lot more review and testing at this
>>> point.
>>=20
>> I don't think it's ready for this merge window.
>=20
> Yes next one I meant (aka this one for development perspective :)).
>=20
>> I read the early
>> patches again, and I think they make the membarrier code worse, not
>> better.
>=20
> Mathieu and I disagree, so we are at an impasse.

Well actually not really, I went and cut out the exit_lazy_tlb stuff
from the patch series, those are better to be untangled anyway. I think=20
an earlier version had something in exit_lazy_tlb for the mm refcounting=20
change but it's not required now anyway.

I'll split them out and just work on the shoot lazies series for now, I
might revisit exit_lazy_tlb after the dust settles from that and the
current membarrier changes. I'll test and repost shortly.

Thanks,
Nick