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[209.85.218.48]) by smtp.gmail.com with ESMTPSA id c23-20020a056402121700b0050da0ff6197sm748207edw.34.2023.05.25.10.17.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 May 2023 10:17:34 -0700 (PDT) Received: by mail-ej1-f48.google.com with SMTP id a640c23a62f3a-96f9cfa7eddso162396466b.2 for ; Thu, 25 May 2023 10:17:34 -0700 (PDT) X-Received: by 2002:a17:907:9289:b0:96a:6723:da48 with SMTP id bw9-20020a170907928900b0096a6723da48mr1860929ejc.75.1685035054236; Thu, 25 May 2023 10:17:34 -0700 (PDT) MIME-Version: 1.0 References: <20230522205744.2825689-1-dhowells@redhat.com> <3068545.1684872971@warthog.procyon.org.uk> <3215177.1684918030@warthog.procyon.org.uk> <98511.1685034443@warthog.procyon.org.uk> In-Reply-To: <98511.1685034443@warthog.procyon.org.uk> From: Linus Torvalds Date: Thu, 25 May 2023 10:17:17 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Extending page pinning into fs/direct-io.c To: David Howells Cc: David Hildenbrand , Christoph Hellwig , Jens Axboe , Al Viro , Matthew Wilcox , Jan Kara , Jeff Layton , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Christian Brauner , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: CB80912001E X-Rspam-User: X-Stat-Signature: ju1qgs64y78uttwncdkzneu86n3ofq18 X-Rspamd-Server: rspam01 X-HE-Tag: 1685035072-190750 X-HE-Meta: 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 pIxZF6Z2 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 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 Thu, May 25, 2023 at 10:07=E2=80=AFAM David Howells wrote: > > Should everywhere that is using ZERO_PAGE(0) actually be using my_zero_pf= n()? No, that would just make code uglier for no reason, because then you have to turn that pfn into a virtual address. So if what you *want* is a pfn to begin with, then use, use my_zero_pfn(). But if what you want is just the virtual address, use ZERO_PAGE(). And if you are going to map it at some address, give it the address you're going to use, otherwise just do zero for "whatever". The only thing you can't use ZERO_PAGE(0) for is literally that "is this a zero page" address comparison, because ZERO_PAGE(0) is just _one_ address. Linus