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Sun, 13 Dec 2020 21:53:46 -0800 (PST) Received: from localhost ([220.240.228.148]) by smtp.gmail.com with ESMTPSA id v126sm17639802pfb.137.2020.12.13.21.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Dec 2020 21:53:45 -0800 (PST) Date: Mon, 14 Dec 2020 15:53:40 +1000 From: Nicholas Piggin Subject: Re: [PATCH 2/8] x86: use exit_lazy_tlb rather than membarrier_mm_sync_core_before_usermode To: Andy Lutomirski Cc: Anton Blanchard , Arnd Bergmann , linux-arch , LKML , Linux-MM , linuxppc-dev , Mathieu Desnoyers , Peter Zijlstra , X86 ML References: <1607152918.fkgmomgfw9.astroid@bobo.none> <116A6B40-C77B-4B6A-897B-18342CD62CEC@amacapital.net> <1607209402.fogfsh8ov4.astroid@bobo.none> <1607224014.8xeujbleij.astroid@bobo.none> <1607918323.6muyu2l982.astroid@bobo.none> In-Reply-To: <1607918323.6muyu2l982.astroid@bobo.none> MIME-Version: 1.0 Message-Id: <1607924970.hd6nln4qe5.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 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