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[209.85.208.177]) by smtp.gmail.com with ESMTPSA id 23sm1114776ljv.54.2020.06.03.20.19.25 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Jun 2020 20:19:25 -0700 (PDT) Received: by mail-lj1-f177.google.com with SMTP id b6so5436901ljj.1 for ; Wed, 03 Jun 2020 20:19:25 -0700 (PDT) X-Received: by 2002:a05:651c:2c6:: with SMTP id f6mr1001246ljo.371.1591240764798; Wed, 03 Jun 2020 20:19:24 -0700 (PDT) MIME-Version: 1.0 References: <20200603155549.e041363450869eaae4c7f05b@linux-foundation.org> <20200603225630.dODblpnlR%akpm@linux-foundation.org> In-Reply-To: From: Linus Torvalds Date: Wed, 3 Jun 2020 20:19:08 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 004/131] mm/gup: refactor and de-duplicate gup_fast() code To: Andrew Morton Cc: Dave Airlie , Chris Wilson , Daniel Vetter , Jani Nikula , jhubbard@nvidia.com, Joonas Lahtinen , jrdr.linux@gmail.com, Linux-MM , matthew.auld@intel.com, mm-commits@vger.kernel.org, Rodrigo Vivi , tvrtko.ursulin@intel.com, Matthew Wilcox Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: A5DCC8005A6A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jun 3, 2020 at 7:19 PM Linus Torvalds wrote: > > Now it uses FOLL_WRITE (because that's what > internal_get_user_pages_fast() does), which will disallow read-only > pages (in order to handle them properly for COW in the slow path), and > then the fact that the slow-path is entirely disabled for this case > means that it doesn't work at all. I have tried to fix it up, partly by editing the patches directly, and partly by then trying to fix up comments after-the-fact. The end result looks possibly correct after it all. But it would have been easier had I just had a merge conflict to deal with, rather than trying to fix up patches. Will do more testing etc before really merging and then pushing out. Linus