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 680F5C433EF for ; Mon, 4 Jul 2022 21:04:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B39256B0071; Mon, 4 Jul 2022 17:04:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AC28A6B0073; Mon, 4 Jul 2022 17:04:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 989626B0074; Mon, 4 Jul 2022 17:04:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 862446B0071 for ; Mon, 4 Jul 2022 17:04:50 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 537A960394 for ; Mon, 4 Jul 2022 21:04:50 +0000 (UTC) X-FDA: 79650646740.05.985CF97 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) by imf08.hostedemail.com (Postfix) with ESMTP id 5F8E5160041 for ; Mon, 4 Jul 2022 21:04:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=T4NEq+eMSGAkYEOA0B+r4pdVqAgo1X2D4OJSO7fEkNY=; b=AQZXT4X26RLQ+tZazISD4HjcHj uY43HvoKZBqSRJnUKTH2W+dL9c2FSeIpL0aPm++Jao5qMRkopG7Jw78ME/C9ubLOhmUX+Xe7dSXYQ Y4FAtgFK9dsEA66ZijK/hRjM+EGhXfzM0WZiFkcx1oNYvhS6AJBKQc5wmRfGCUBsBMX/1JsDNApIz YBywIfgH9bOTV56kOM/DAJAd+721Hutx1uqwOZ01LB6wtndOMYcaI3ulgDRCfq9YpymEaNwddqg+d rieM3tFld/azhG0yquNoj12g5gKcvOdTmSk3OfOJ8i9qf1cUd7Sz2LDQqiSnIeNKzaW0yUC3aW2YX O9uT8OhQ==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.95 #2 (Red Hat Linux)) id 1o8TEm-0088kl-TL; Mon, 04 Jul 2022 21:04:09 +0000 Date: Mon, 4 Jul 2022 22:04:08 +0100 From: Al Viro To: Linus Torvalds Cc: Alexander Potapenko , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev , Linux-MM , linux-arch , Linux Kernel Mailing List , Evgenii Stepanov , Nathan Chancellor , Nick Desaulniers , Segher Boessenkool , Vitaly Buka , linux-toolchains Subject: Re: [PATCH v4 43/45] namei: initialize parameters passed to step_into() Message-ID: References: <20220701142310.2188015-44-glider@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656968688; h=from:from:sender: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=T4NEq+eMSGAkYEOA0B+r4pdVqAgo1X2D4OJSO7fEkNY=; b=wYkUgkCQO6OPT+qfJjd/G1CRyBhZ0+jmu2PcNRy1hbl4ocEAkBgL9zGTSUor/xT5iEaHx+ i4QIbXwwUg0WDm0P7ZMtENbcxxcGltMsBB8ajpEcLc96MgoChv5aNJ0SMQUUF7YfZ5Mdye EH1gQAPwITJaOx7ZA8xbnK+Pc2x2BO8= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=linux.org.uk header.s=zeniv-20220401 header.b=AQZXT4X2; dmarc=pass (policy=none) header.from=zeniv.linux.org.uk; spf=none (imf08.hostedemail.com: domain of viro@ftp.linux.org.uk has no SPF policy when checking 62.89.141.173) smtp.mailfrom=viro@ftp.linux.org.uk ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656968688; a=rsa-sha256; cv=none; b=eS6LmeE4tkFRDxn/Tfu5qNKbY0rAS+a2Y65cDTwcDd9WrS+u0UnU2sNWS/DeKFnNXanHHx afuWUWGisFBg068QOItc10nsbTNddpPbpUqRjtroGFkm5W1F5nxm/K/1izT1qvGAFQqaja hYC51RfIaXT3EuelU0xHz1la2rwpYrk= Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=linux.org.uk header.s=zeniv-20220401 header.b=AQZXT4X2; dmarc=pass (policy=none) header.from=zeniv.linux.org.uk; spf=none (imf08.hostedemail.com: domain of viro@ftp.linux.org.uk has no SPF policy when checking 62.89.141.173) smtp.mailfrom=viro@ftp.linux.org.uk X-Stat-Signature: ao3hrn8xq479tycdtp94dd9jpwg7xxg6 X-Rspamd-Queue-Id: 5F8E5160041 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1656968688-84055 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 04, 2022 at 01:51:16PM -0700, Linus Torvalds wrote: > On Mon, Jul 4, 2022 at 1:46 PM Al Viro wrote: > > > > Why is that a problem? It could have been moved to another parent, > > but so it could after we'd crossed to the mounted and we wouldn't have > > noticed (or cared). > > Yeah, see my other email. > > I agree that it might be a "we don't actually care" situation, where > all we care about that the name was valid at one point (when we picked > up that sequence point). So maybe we don't care about closing it. > > But even if so, I think it might warrant a comment, because I still > feel like we're basically "throwing away" our previous sequence point > information without ever checking it. > > Maybe all we ever care about is basically "this sequence point > protects the dentry inode pointer for the next lookup", and when it > comes to mount points that ends up being immaterial. There is a problem, actually, but it's in a different place... OK, let me try to write something resembling a formal proof and see what falls out.