From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF6F6C7115B for ; Mon, 23 Jun 2025 11:50:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4ECCD6B00B6; Mon, 23 Jun 2025 07:50:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49D026B00B7; Mon, 23 Jun 2025 07:50:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B27C6B00B9; Mon, 23 Jun 2025 07:50:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 29A796B00B6 for ; Mon, 23 Jun 2025 07:50:30 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id B10411A0146 for ; Mon, 23 Jun 2025 11:50:29 +0000 (UTC) X-FDA: 83586497778.25.BD3800A Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf10.hostedemail.com (Postfix) with ESMTP id 25C51C0014 for ; Mon, 23 Jun 2025 11:50:27 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=h+9Z7d1M; spf=pass (imf10.hostedemail.com: domain of brauner@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1750679428; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nB/oAbQ8bav2/CzYpUO89vpHK9TcEuf7gz53S/mdBmw=; b=P2nhe7eU0nMZBAON/TgHozQw3iWFiSFCbgw9WYg3WwdRXX6i1pbk4B0SfZlSdOtwPLbJ4M ELFoNLeQ1L8K7ca/T6gtyNQA9Pz9dHE3o63eQKRB3aLLNrUPZnuxQMYLJ4sm5yr+7jNC/W hWMyituIu1F9+HXaUw7/kTNySIxs/98= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=h+9Z7d1M; spf=pass (imf10.hostedemail.com: domain of brauner@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1750679428; a=rsa-sha256; cv=none; b=n3QpuTMoOu5UEb5FAuN8mtR+tGIbax1KIeRCiSjhM0hSodkxvtjYC9Msxjo12qR1URzTgq KkKXN9oUYk/lHz4txijdhiHIoVaofpggOk/HU7hgOnglSzETxFXtN7IT7JAMKSN6g8Kfx6 q4j9KqCDmhTsjUAMBa8bUGa7895v6dw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id B93B549FA2; Mon, 23 Jun 2025 11:50:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A998C4CEEA; Mon, 23 Jun 2025 11:50:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750679426; bh=ActTs+qIg1fuo+yvfrQokf0GdyTmEgBrTcnMxW4n8hE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=h+9Z7d1MZYThb4BzC0sAtbzRCw2VDvjT/N1z/g0j1L4XdAT9UD9UR9CI4vA1PqZ5d iGYoetZQ/yTHvVS/ZbgCV6707ruW7FBquAvH6tcQoSWF2XFrUnDMGJMCgs7XIUu9av IW6kGBVeQp+V6IAsL2X2DmlZmt0mQSHqNqldozuJBHnoxS1YBLvZwo6zykE9RHGPma 8A2ALmHgOibmvUFWhU2se6YH/2X7g0d4AEwslixKX3ozxncqxUV7LI6NVwu8sBM6CW pnMROxuJ9XK7frRtRVaXfpg0WDw1+6Qf/CU+MVYTl3En2FaWP3alBcvmhfe/8c8H6k 3Qy8HKIFSuqRA== Date: Mon, 23 Jun 2025 13:50:20 +0200 From: Christian Brauner To: David Howells Cc: Andrew Lunn , Eric Dumazet , "David S. Miller" , Jakub Kicinski , David Hildenbrand , John Hubbard , Christoph Hellwig , willy@infradead.org, Al Viro , Miklos Szeredi , torvalds@linux-foundation.org, netdev@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: AF_UNIX/zerocopy/pipe/vmsplice/splice vs FOLL_PIN Message-ID: <20250623-absetzbar-barzahlung-3d124847a2b4@brauner> References: <1069540.1746202908@warthog.procyon.org.uk> <165f5d5b-34f2-40de-b0ec-8c1ca36babe8@lunn.ch> <0aa1b4a2-47b2-40a4-ae14-ce2dd457a1f7@lunn.ch> <1015189.1746187621@warthog.procyon.org.uk> <1021352.1746193306@warthog.procyon.org.uk> <2135907.1747061490@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2135907.1747061490@warthog.procyon.org.uk> X-Rspamd-Server: rspam11 X-Rspam-User: X-Rspamd-Queue-Id: 25C51C0014 X-Stat-Signature: gwkyk7w739ojke5qph6snkbzygnt8wgy X-HE-Tag: 1750679427-434511 X-HE-Meta: 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 ndHKN7Zm ITw5peYez9w2ydV/2yL0v+MBdra9phTfezn/KMLfAoN6d+n3X55D9yGEw1g== 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: List-Subscribe: List-Unsubscribe: On Mon, May 12, 2025 at 03:51:30PM +0100, David Howells wrote: > I'm looking at how to make sendmsg() handle page pinning - and also working > towards supporting the page refcount eventually being removed and only being > available with certain memory types. > > One of the outstanding issues is in sendmsg(). Analogously with DIO writes, > sendmsg() should be pinning memory (FOLL_PIN/GUP) rather than simply getting > refs on it before it attaches it to an sk_buff. Without this, if memory is > spliced into an AF_UNIX socket and then the process forks, that memory gets > attached to the child process, and the child can alter the data, probably by > accident, if the memory is on the stack or in the heap. > > Further, kernel services can use MSG_SPLICE_PAGES to attach memory directly to > an AF_UNIX pipe (though I'm not sure if anyone actually does this). I would possible be interested in using this for the coredump af_unix socket.