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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85F2AC11D00 for ; Thu, 20 Feb 2020 23:03:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 65A06206F4 for ; Thu, 20 Feb 2020 23:03:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729355AbgBTXDQ (ORCPT ); Thu, 20 Feb 2020 18:03:16 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:41308 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729141AbgBTXDP (ORCPT ); Thu, 20 Feb 2020 18:03:15 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4uqb-00G22x-QS; Thu, 20 Feb 2020 23:03:09 +0000 Date: Thu, 20 Feb 2020 23:03:09 +0000 From: Al Viro To: "Eric W. Biederman" Cc: Linus Torvalds , LKML , Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module , Akinobu Mita , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Oleg Nesterov , Solar Designer Subject: Re: [PATCH 4/7] proc: Use d_invalidate in proc_prune_siblings_dcache Message-ID: <20200220230309.GS23230@ZenIV.linux.org.uk> References: <20200212203833.GQ23230@ZenIV.linux.org.uk> <20200212204124.GR23230@ZenIV.linux.org.uk> <87lfp7h422.fsf@x220.int.ebiederm.org> <87pnejf6fz.fsf@x220.int.ebiederm.org> <871rqpaswu.fsf_-_@x220.int.ebiederm.org> <87blpt9e6m.fsf_-_@x220.int.ebiederm.org> <20200220225420.GR23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200220225420.GR23230@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 20, 2020 at 10:54:20PM +0000, Al Viro wrote: > On Thu, Feb 20, 2020 at 02:49:53PM -0600, Eric W. Biederman wrote: > > > > The function d_prune_aliases has the problem that it will only prune > > aliases thare are completely unused. It will not remove aliases for > > the dcache or even think of removing mounts from the dcache. For that > > behavior d_invalidate is needed. > > > > To use d_invalidate replace d_prune_aliases with d_find_alias > > followed by d_invalidate and dput. This is safe and complete > > because no inode in proc has any hardlinks or aliases. > > s/no inode.*/it's a fucking directory inode./ Wait... You are using it for sysctls as well? Ho-hum... The thing is, for sysctls you are likely to run into consequent entries with the same superblock, making for a big pile of useless playing with ->s_active... And yes, that applied to mainline as well