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[209.85.167.44]) by smtp.gmail.com with ESMTPSA id f19sm3129693lfv.100.2022.01.04.13.24.43 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Jan 2022 13:24:43 -0800 (PST) Received: by mail-lf1-f44.google.com with SMTP id g26so84529798lfv.11 for ; Tue, 04 Jan 2022 13:24:43 -0800 (PST) X-Received: by 2002:a05:6000:10d2:: with SMTP id b18mr43639104wrx.193.1641331473028; Tue, 04 Jan 2022 13:24:33 -0800 (PST) MIME-Version: 1.0 References: <20220104202227.2903605-1-yuzhao@google.com> <20220104202227.2903605-3-yuzhao@google.com> In-Reply-To: <20220104202227.2903605-3-yuzhao@google.com> From: Linus Torvalds Date: Tue, 4 Jan 2022 13:24:17 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 2/9] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG To: Yu Zhao Cc: Andrew Morton , Andi Kleen , Catalin Marinas , Dave Hansen , Hillf Danton , Jens Axboe , Jesse Barnes , Johannes Weiner , Jonathan Corbet , Matthew Wilcox , Mel Gorman , Michael Larabel , Michal Hocko , Rik van Riel , Vlastimil Babka , Will Deacon , Ying Huang , Linux ARM , "open list:DOCUMENTATION" , Linux Kernel Mailing List , Linux-MM , page-reclaim@google.com, "the arch/x86 maintainers" , Konstantin Kharlamov Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: EFBD918000C X-Stat-Signature: 6tcim9s9zrti8zs4wqom1p38eutmiryk Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=MfmNtueD; dmarc=none; spf=pass (imf16.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.208.170 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-HE-Tag: 1641331485-882991 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: On Tue, Jan 4, 2022 at 12:23 PM Yu Zhao wrote: > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 5c2ccb85f2ef..5a4843242f09 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -85,6 +85,7 @@ config X86 > + select ARCH_HAS_NONLEAF_PMD_YOUNG if X86_64 Why is this limited to 64-bit? I'm ok with that - maybe it's a simple case of "this is not worth doing on 32-bit", but I'd like the explanation to be written out. Right now the commit message literally points the architecture manual that sio relevant for both 32-bit and 64-bit - and then the patch itself makes it 64-bit only. Linus