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Tue, 14 Apr 2020 07:48:18 -0700 (PDT) Received: from localhost ([203.18.28.220]) by smtp.gmail.com with ESMTPSA id k12sm10439963pgj.33.2020.04.14.07.48.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2020 07:48:17 -0700 (PDT) Date: Wed, 15 Apr 2020 00:48:13 +1000 From: Nicholas Piggin Subject: Re: [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings To: Christoph Hellwig References: <20200413125303.423864-1-npiggin@gmail.com> <20200413125303.423864-5-npiggin@gmail.com> <20200414072316.GA5503@infradead.org> <1586864403.0qfilei2ft.astroid@bobo.none> <20200414130203.GA20867@infradead.org> In-Reply-To: <20200414130203.GA20867@infradead.org> MIME-Version: 1.0 Message-Id: <1586875675.f8q1grbltc.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Will Deacon , Catalin Marinas , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Christoph Hellwig's message of April 14, 2020 11:02 pm: > On Tue, Apr 14, 2020 at 10:13:44PM +1000, Nicholas Piggin wrote: >> Which case? Usually the answer would be because you don't want to use >> contiguous physical memory and/or you don't want to use the linear=20 >> mapping. >=20 > But with huge pages you do by definition already use large contiguous > areas. So you want allocations larger than "small" huge pages but not > using gigantic pages using vmalloc? Yes. Thanks, Nick