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[217.140.101.70]) by mx.google.com with ESMTP id w27si2342049edi.262.2019.03.04.05.16.54 for ; Mon, 04 Mar 2019 05:16:54 -0800 (PST) Received-SPF: pass (google.com: domain of steven.price@arm.com designates 217.140.101.70 as permitted sender) client-ip=217.140.101.70; Authentication-Results: mx.google.com; spf=pass (google.com: domain of steven.price@arm.com designates 217.140.101.70 as permitted sender) smtp.mailfrom=steven.price@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F35CEEBD; Mon, 4 Mar 2019 05:16:52 -0800 (PST) Received: from [10.1.196.69] (e112269-lin.cambridge.arm.com [10.1.196.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5F6333F575; Mon, 4 Mar 2019 05:16:49 -0800 (PST) Subject: Re: [PATCH v3 08/34] ia64: mm: Add p?d_large() definitions To: "Kirill A. Shutemov" Cc: Mark Rutland , linux-ia64@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Dave Hansen , Will Deacon , linux-mm@kvack.org, "H. Peter Anvin" , "Liang, Kan" , x86@kernel.org, Ingo Molnar , Fenghua Yu , Arnd Bergmann , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Borislav Petkov , Andy Lutomirski , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Tony Luck , Ard Biesheuvel , linux-kernel@vger.kernel.org, James Morse References: <20190227170608.27963-1-steven.price@arm.com> <20190227170608.27963-9-steven.price@arm.com> <20190301215728.nk7466zohdlgelcb@kshutemo-mobl1> From: Steven Price Message-ID: <15100043-26e4-2ee1-28fe-101e12f74926@arm.com> Date: Mon, 4 Mar 2019 13:16:47 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190301215728.nk7466zohdlgelcb@kshutemo-mobl1> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit 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 01/03/2019 21:57, Kirill A. Shutemov wrote: > On Wed, Feb 27, 2019 at 05:05:42PM +0000, Steven Price wrote: >> walk_page_range() is going to be allowed to walk page tables other than >> those of user space. For this it needs to know when it has reached a >> 'leaf' entry in the page tables. This information is provided by the >> p?d_large() functions/macros. >> >> For ia64 leaf entries are always at the lowest level, so implement >> stubs returning 0. > > Are you sure about this? I see pte_mkhuge defined for ia64 and Kconfig > contains hugetlb references. > I'm not completely familiar with ia64, but my understanding is that it doesn't have the situation where a page table walk ends early - there is always the full depth of entries. The p?d_huge() functions always return 0. However my understanding is that it does support huge TLB entries, so when populating the TLB a region larger than a standard page can be mapped. I'd definitely welcome review by someone more familiar with ia64 to check my assumptions. Thanks, Steve