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[209.85.208.170]) by smtp.gmail.com with ESMTPSA id t21sm3217480lfd.85.2019.06.03.09.08.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Jun 2019 09:08:59 -0700 (PDT) Received: by mail-lj1-f170.google.com with SMTP id a21so1555610ljh.7 for ; Mon, 03 Jun 2019 09:08:59 -0700 (PDT) X-Received: by 2002:a2e:4246:: with SMTP id p67mr14377820lja.44.1559578139147; Mon, 03 Jun 2019 09:08:59 -0700 (PDT) MIME-Version: 1.0 References: <20190601074959.14036-1-hch@lst.de> <20190601074959.14036-4-hch@lst.de> <20190603074121.GA22920@lst.de> In-Reply-To: <20190603074121.GA22920@lst.de> From: Linus Torvalds Date: Mon, 3 Jun 2019 09:08:43 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 03/16] mm: simplify gup_fast_permitted To: Christoph Hellwig Cc: Paul Burton , James Hogan , Yoshinori Sato , Rich Felker , "David S. Miller" , Nicholas Piggin , Khalid Aziz , Andrey Konovalov , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linux-mips@vger.kernel.org, Linux-sh list , sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Linux-MM , "the arch/x86 maintainers" , Linux List Kernel Mailing Content-Type: text/plain; charset="UTF-8" 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 Mon, Jun 3, 2019 at 12:41 AM Christoph Hellwig wrote: > > I only removed a duplicate of it. I don't see any remaining cases. > The full (old) code in get_user_pages_fast() looks like this: > > if (nr_pages <= 0) > return 0; > > if (unlikely(!access_ok((void __user *)start, len))) > return -EFAULT; > > if (gup_fast_permitted(start, nr_pages)) { Yes, and that code was correct. The new code has no test at all for "nr_pages == 0", afaik. Linus