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Fri, 15 Jan 2021 09:03:42 -0800 (PST) Subject: Re: [PATCH] drm/i915/userptr: detect un-GUP-able pages early To: Chris Wilson , =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Matthew Auld , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <161072980241.18103.11713889922046524226@build.alporthouse.com> From: Jinoh Kang Autocrypt: addr=jinoh.kang.kr@gmail.com; keydata= xsFNBF/Q7MUBEADVIU6g5ui3gcTQV9jbneUb6xdUQJtEDOWG6pThD+nKAwQFYtZpCUSWgGVg osMQTyZu7HpEMvxoYNmO+1ZHtARugq2tl6BH11vEJgTsoF8IFrgyXNlinS+Kq6I8s6py96Pl Fk2b9Y3ok64DJUrmFjfgCAxO0RY/ZFS1vXMqibExzMLODTChrXal0Z9tjxQBkARPXeDmVg8c qW0121/3ODyi04jri34f5luRQe2PMJsqKAmd6Ok9zNkvc3wQZw7t3MiMEJjf1/eZa/He4OoI CO0zQY9dRhQBqgO67lnVziCRfRb4WCHxO03zE7C8ud/UOmuMM4Qh8rAyW3sJ2TbIqwvQepuc vC/Q+Av0GtuUCArUw4GbOibUDxhe1eTZViIYAghkzOxUWeDs1PXRPVnRu6PAGsQP39/2ZPAB wune9t2SEs4o2Js0Vx0c2O/vMXt3uHqtaGNdCJgqlBkNXHlrv47wF7bBMQSf4SepAg+1ZqfI wGgEWmWhBV+8Kqyb1zYIAPsqyvl/2E//XcvKk/70q0QhASGkUvEI8AWAGDdkVPrBfwIqhvWY ycMnOl12k5e161uvL1NiUIbvG41/lCzQqhmaDfYznwsC1YRfx/STNaoIdBqR+niUhJbEGpfy z1BqOYMHpFx1sKFfJesMDyLBDaQBuO5X2mKmpHvCyfy9ouBNmQARAQABzSRKaW5vaCBLYW5n IDxqaW5vaC5rYW5nLmtyQGdtYWlsLmNvbT7CwZQEEwEIAD4WIQRCo/a4eJTkYSJv2ktDGVOB YOvS5gUCX9DsxQIbLwUJAeEzgAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRBDGVOBYOvS 5mhUEACHpb/kXi02ED27HYHk0j4QFokIFSBx4gdMueu86OQzQuJ4LqOZQmX0IsvedmLuECot kNE7uhpINj9qNFUZjkD26N2kpnh1EUiHHhGnPAi0KCjsF4t9IR7NgwyeFgScmKAGvDQeLSHZ V3A9/ZIuo2cwp9nJKFkljE4P+ADmTpOv2j0XM8o+y7VILnNwanDXuyKh8T37oyecgP0y4aiN QcsCfCKgyomFuDomNrj8CwyIS36oyYJwXxl34KBaNLmXRmLFIleApcFkqBewSdAqBWqbu3yt V/zbK5uTwx4JKatPk1zgvJKfdHuQW//+H0Rufvosk7JUNkft5T9Cx7Fihts+4HWzvLFU97h8 E0Tby5paW3/Z8UGRHf+1eYfS39/9hN/Wphw4eoXpN9GDkgMpzKauquHEuKNKwpQ3LuGM4cO7 TXJLF3Zyx0vwMTu/v4gvILBhppc2MlGDeW48eKH4i4oJhpvjwFku7rh8IG/d0F4I0RpaiqYb l3lw0niIVbTKguoMXxhmZLGn8uRuo7CLpqFZyaGOFgPEV889sHE78+FqrXv6cT00cOh6a6p5 2XlLC6TphePZ56HCcr9n5E2elEI3eCOsGp6UnOPV9mxjmZ/fd512B3goflgq+T9TgOOUSnX7 ioz/igRhHwjSZd3nlocCmHvWpQ6RaGBH/Bi5lOorts7BTQRf0OzFARAAx8fgWCVxM1CZWKGj 5HKYV5IJy4D5/YVvi2ob05I18a5lz1dXLOu598rL9gX3V9bZ1k6Q7lh5glNyITnTnlAnpVNu zXbPlbJb35Bwmns3OgGi0tCPWxlsn5GZacXUnByVylwcR0OKA9ekWB2CJk0BVpBzKf3c/JgS bLNKNG9lpDlypJGMZBWbwODK5HdKKridfUJiFHdE6wErdryjTT75NDTzQoKTeMG/TgyBTLY5 Ebc6AXryTGGi2THU/ufC+m7/NMhXQGR1dc1dZsPUELXR4XfE36HVfKi3lHT6jY+ylQqIhiQr haAun5mpitoOCWyeMvQCrXB+Qe1JzpVHQB2mPZ2RAMD82+wZE3kGh3XiOheY+NFb2ahTvZMe otf3/uH6k0LehKt2jVbVjaxAelqCMjBzOlPeaYlD1NTXXX9RGRUUQThfJezcCt/iOv64wayV N6ua8dMCrFWzS66bsrsdSmlucB/S7VvNLCFStSJnoW1s4MdQ387NVK3NC41tpx9qVzwIc4X/ 0jS2xA2EHC/+HMx8CXQiXPV98WP2Hd4TEmX4SAiIXuiXrN84ANJx/bPn/iS3QXBiY1YNI787 oinlL4BJTM+rpZgTgsQk3M0QfenrVIqn7c/L+vk7r0TV4oq/+w2mKLAQX3co00+mrRfANajb xA4oODN5wd649jV7NZUAEQEAAcLDsgQYAQgAJhYhBEKj9rh4lORhIm/aS0MZU4Fg69LmBQJf 0OzFAhsuBQkB4TOAAkAJEEMZU4Fg69LmwXQgBBkBCAAdFiEEzGktrvc/U3kFXd9AGlqQRGyE q/UFAl/Q7MUACgkQGlqQRGyEq/WMqBAAhGe/MaK0zyYkMD7ZPgg7rCBhkFAqZg7/UiQE4l1S 0vZ9HJjV6QhK9MJknzTKWr+r7G1xvfCfVTEubKmFfdgTXXEM61EEGOnGbptwoKVzmYLJpoo3 WvEHfGoF+vnc4r58GSxfKZCnhn7wRrRs8toGP3FNh6V3wQ2JEXhaT098IpUSo2RnuULzUvFU GG0NxB6e9nCoppLF3JUDnf6DdN00gkBgGVd2iKuK8P3Zzy/GJPp4GSw0Y1sFglab71/e9mtQ /QZ3z+PgFyAH1vPzmPh0hC5thbdhBoJWrHDpYM7RzcfJOnAyPmo9FufEB9wREESK0yy+2h9l fq56H5aBch3TSb23cIiA4x7OhHgkaTmsURiSSh9eP2/eXedClRXvvGMoc/LP837qtZz52eDD HcLy7AA2+hPbDqIy+ZxmYOw9bjbLH6QGv2hKGvDwtEF12r4MaYHiae/vbbIOjkQ21m9bc6gO 5kPqWanl2rpka4PdDmg125MTNyBOZk+83exMY+56eTViccMHs+vUmtqxluR539B8sCHalcci 3Udb4vUWRNFweYM85utgbSR3MCdsA6r/wuLwIA/vsKzaSTjg2I7KO4/KiNV3AUChafXjAkZM hPs3OPukWRSAfHSixxyygLTB52irbfhV/qVsS5RKe2nL6PClmumU9eOdljrZ6FW8mxt93A// YocGSec7S3LeWzxauzcQn1TMtuLLMAUs/CTYHBhQDf2UMprHd2O9cpwNULtedXtRSkug/lA4 BsGzSJsbgoGkR4/D9PQK2FeqzvAkrOmuQqz6iCMxOnaJLAROzTaKlpAqf+h7kP7979RkXttw Ax75QQO2oUKhqehvYo1MRZJBVUa4Oq7gBZAe7kmRI78fKAOGUZDQtOpGuvAawR+U6MubgB8O 8ZP/4DV8x0uzpWugpuCj2+d2heaqrsMumomWt7w4utfz8LFETaK4eIbswwEgB1PpT9nA+0vr 03mgjzWiW7D5jDPCegZ9a2JcIwKhWTdNR1uayj5hG7rdvScL5zMXlMHGK6Jb9EvBTnmnW/Bh mBRUTfAckuZP2GGvcnIv86pcVbLfRsENgN9XVjfn+I+r3pTMjhSIb/B0q2acaINe3GUWIq9V o01sX4DgkHW6wE6hlMfxxBq5Avu180VZ96rCilkf8abWidtPn/7IP31CSLz5JNL0x2OQC+WD tvgog5utx5uRL5mZPJmMTVD1t/FKGaIR1PpGy4e0g15Y9EkpFEYBYZl3ttXQM456ZqifB/Wb pgaToX5LrY7TCHQe9skAN/RsppjrL8HCxF0rz6/LKnUCPC71/dfBIrIigYeBdK9UkNXAq/5c Nv8WeK9sQ0q6RmWqnT1HwyCBsVRR18k6XBM= Message-ID: <1277b18e-9a19-fd0c-41fc-4923bcd772fd@gmail.com> Date: Fri, 15 Jan 2021 17:03:18 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Firefox/78.0 MIME-Version: 1.0 In-Reply-To: <161072980241.18103.11713889922046524226@build.alporthouse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/15/21 4:56 PM, Chris Wilson wrote: > Quoting Jinoh Kang (2021-01-15 16:23:31) >> If GUP-ineligible pages are passed to a GEM userptr object, -EFAULT is >> returned only when the object is actually bound. >> >> The xf86-video-intel userspace driver cannot differentiate this >> condition, and marks the GPU as wedged. > > The idea was to call gem_set_domain on the object to validate the pages > after creation. I only did that for read-only... I did however make mesa > use set-domain for validation. Thanks for the info! > > As a question how are you getting to call userptr on something that > wasn't passed by SHM ipc? Basically XShmAttachFd, which is not exposed on libX11. > >> This not only disables graphics >> acceleration but may also cripple other functions such as VT switch. > > That should be a non-sequitur; certainly VT switch works without ever > using the GPU. Not that VT switch doesn't work; rather, there's some heavy graphic artifacts such as blank rectangles or part of window going completely transparent. I suppose that's another issue. > >> Solve this by "prefaulting" user pages on GEM object creation, testing >> whether all pages are eligible for get_user_pages() in the process. >> On failure, return -EFAULT so that userspace can fallback to software >> blitting. > > See https://patchwork.freedesktop.org/series/33449/ for adding PROBE | > POPULATE flags. > > But we can just use set-domain. So this patch was unnecessary. Thanks for the pointer as to how to patch the userspace. > -Chris > -- Sincerely, Jinoh Kang