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b=kXvSlVnDH15cWbO+1dz7W4fA+T+ypLAoZ5VIau7XmbxS6feD3VAzBV1LffLw5p6nH NQGjuMGAlXxYHVEuvpQ0vcRtODFwdjaIc0xgimwJ4L/8XTFRcIN9lwnrg0BoCXQTqk 386sgwGM/6HyI+6Tuz5K8dPrXes8XavbQRl9tpJKTcviHkxSJb1Knt8DPmVJw+J9zN poVRvHhxtbzIXdvplQThOA+xbji8a5V3vMiF9TSUAjcLn8ogW4RhCHq9dwQuEuLFJE oThSBPZwm4yzahMxKEfSeVBAu7ay/18ITsC084l18AwdnVqAfO7yH3ERFL3W36MsR7 HQiXEUK1N8C8g== Message-ID: <78127b64-d4ba-4e72-87fd-28e26f989de9@kernel.org> Date: Sun, 25 Oct 2026 11:56:58 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fs/proc/task_mmu: return -ENOTTY for unknown pagemap ioctls To: Hengyu Liang , akpm@linux-foundation.org, linux-mm@kvack.org Cc: liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, jannh@google.com, pfalcato@suse.de, usama.anjum@arm.com, avagin@gmail.com, mirq-linux@rere.qmqm.pl, arnd@arndb.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261023181300.3366487-1-hengyul@cs.unc.edu> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6737FC0005 X-Stat-Signature: adh1r9rjp8hrtidnyu3ge1n4mq683jyo X-Rspam-User: X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1792929154-341681 X-HE-Meta: U2FsdGVkX1/jPvSFr1ZublwezrqEYb+6RHTHRM1iEwfjgyffiXo6GyheNvsuk2QPPbGZe3CFb2WnbfRN/+Wdx1kHEkeNVEHtz9Xik3BspOR+FoMwXr6zwMvhyKbt1Zd9K2n9LHeqZmmJvbgpqwAuOEVNSIB5ZSSyoh2DH4DpBZ+OIajP80NXcwhV9Y1wPaSsWEz3ea2eMtRBmxFrCQhRHUzO+3OA5jLSoNi4fBZ6H1wS07JBVgGq0Uzj3DFbiSzv3wWvosbYvTpQLh9uEotxQs+dDGON4C9DNKYn3o3wMWxo/zCTBKybQQzhUrxd1KS593Zf7ryWgm8gIe2kQlzCgJQ2X6rI23eJh1roSoKh/DMvKqlvHpWDDAdZGzd2L5oUK5+vnseWJAMlGXJWAuZCzq1v5rj2y6KHhxwjhDMHYns9EShVWWpitu0s8OaCkMRgJlalozO6ypkiM1K3KjwbJkF08ExJPdagA7F25MTkiidl1wlgOiGMcRJTOpyqldxDMwIyIvyyLUFvigGvNZWRJIx+7dRFhyCkK0b1ZPm4jZpN5EPv4s1C/1jmUZSxfzw6X9IASyXFxoLVfXS/CUE46RBOyiMOl8dDyvWGYfiMWO8IzjyvUGQtDGKggitKTuzbjr/PhUN3ZVdKlk0CRfB7YqganXDuqgVSiVrWllaz0BDkRUofUJCMiViJ8SRRDGmzDDk1/4wJ3fg8UEi4YvWK4IEyn+5Yavu89jelwJbGsdcCU501Gw+76mLudIyWJfTUNdNRDlyzgImCSAePxkKlEMdGPnxFsseFFMOpS98oi8/rN0GWrcHjtfmsIwjBnQJQ271aXjpiYtCBkxqT7AqMFwo7wqHc9W8PDN1qlO0ouiqlempyd1CMvIvKLKj+cGo7Kl3iaszjNDYm14gYd9apcGuQ3/nKcwG6EcNHg9N+ChE6ZZGuhMTJpKNPfjl7TrgSYzbHlAt/zxn3qzmi8Lk LZzct6qv OyXsIj9CzjtiV2OIr+1dLagiFAUwC+NP4SR4lAF923kGt7gIaStZpx9COpN2P4ksE0y/3pxI2d6joL2L2xxWojHPnc6zM8w6cO4OFTCYcZfAz77wgWNq3KB9SJVd4553n79YwngoKCcTNJk7Kj7IuWzKFUE/y84UKz0gcpReGl789NHbPf1K8hOqg98M/Zc0peMT2Ja88NXtrxNqzXxJXG6HGNPiNs5/X8q6zlOICqJiJ1bZp/D0YrdzamQKBpEn0Z8AEJQGPjxNlxNxHUNu4EGXFmifZoKapeI24rA2A6j8dCbaeGGqBVSNM+Pbi94yEkDLkYVmf6+URwxQHN4ksyGm9zcmjFvVMdO6ziXpxpcLVMmQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/23/26 20:13, Hengyu Liang wrote: > Commit 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and > optionally clear info about PTEs") made do_pagemap_cmd() the ioctl > handler of /proc//pagemap. > > However, do_pagemap_cmd() returns -EINVAL for every command other than > PAGEMAP_SCAN. Before that commit, pagemap had no ioctl handler, and > the VFS returned -ENOTTY for these commands. As of now, they fail with > EINVAL, so tcgetattr() and isatty() on pagemap report EINVAL instead > of ENOTTY. > > The issue can be reproduced with a simple C program: > > #include > #include > #include > > int main(void) > { > struct termios t; > int fd = open("/proc/self/pagemap", O_RDONLY); > > if (tcgetattr(fd, &t) < 0) > perror("tcgetattr"); > return 0; > } > > Before that commit, the result is: > > tcgetattr: Inappropriate ioctl for device > > After that commit, the result is: > > tcgetattr: Invalid argument > > This patch will return -ENOIOCTLCMD for unknown commands, as > procfs_procmap_ioctl() in the same file does, so that the VFS turns it > into -ENOTTY. > > Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs") > Cc: stable@vger.kernel.org > Signed-off-by: Hengyu Liang > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David