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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kXvSlVnD; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81698606A31A; Sun, 25 Oct 2026 11:52:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=kXvSlVnD Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46D311F01825; Sun, 25 Oct 2026 11:52:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792929153; bh=9CEWfORfntv8VkhsX5SGmYSPLl0+f9APEy3k75g3Ges=; h=Date:Subject:To:Cc:References:From:In-Reply-To; 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-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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 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