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[213.95.11.211]) by mx.google.com with ESMTPS id c9si35021924wmc.24.2019.07.23.08.36.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 08:36:42 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) client-ip=213.95.11.211; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de Received: by verein.lst.de (Postfix, from userid 2407) id A348468B02; Tue, 23 Jul 2019 17:36:40 +0200 (CEST) Date: Tue, 23 Jul 2019 17:36:40 +0200 From: Christoph Hellwig To: John Hubbard Cc: Christoph Hellwig , john.hubbard@gmail.com, Andrew Morton , Alexander Viro , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Boaz Harrosh , Daniel Vetter , Dan Williams , Dave Chinner , David Airlie , "David S . Miller" , Ilya Dryomov , Jan Kara , Jason Gunthorpe , Jens Axboe , =?iso-8859-1?B?Suly9G1l?= Glisse , Johannes Thumshirn , Magnus Karlsson , Matthew Wilcox , Miklos Szeredi , Ming Lei , Sage Weil , Santosh Shilimkar , Yan Zheng , netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, LKML Subject: Re: [PATCH 1/3] mm/gup: introduce __put_user_pages() Message-ID: <20190723153640.GB720@lst.de> References: <20190722223415.13269-1-jhubbard@nvidia.com> <20190722223415.13269-2-jhubbard@nvidia.com> <20190723055359.GC17148@lst.de> <8ab4899c-ec12-a713-cac2-d951fff2a347@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8ab4899c-ec12-a713-cac2-d951fff2a347@nvidia.com> User-Agent: Mutt/1.5.17 (2007-11-01) 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, Jul 22, 2019 at 11:33:32PM -0700, John Hubbard wrote: > I'm seeing about 18 places where set_page_dirty() is used, in the call site > conversions so far, and about 20 places where set_page_dirty_lock() is > used. So without knowing how many of the former (if any) represent bugs, > you can see why the proposal here supports both DIRTY and DIRTY_LOCK. Well, it should be fairly easy to audit. set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off. Which should basically be never or almost never.