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 B0D11C352A4 for ; Wed, 12 Feb 2020 20:38:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9234E24677 for ; Wed, 12 Feb 2020 20:38:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728575AbgBLUik (ORCPT ); Wed, 12 Feb 2020 15:38:40 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:43838 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727692AbgBLUik (ORCPT ); Wed, 12 Feb 2020 15:38:40 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1ymH-00BamE-5t; Wed, 12 Feb 2020 20:38:33 +0000 Date: Wed, 12 Feb 2020 20:38:33 +0000 From: Al Viro To: Linus Torvalds Cc: "Eric W. Biederman" , 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 v8 07/11] proc: flush task dcache entries from all procfs instances Message-ID: <20200212203833.GQ23230@ZenIV.linux.org.uk> References: <20200210150519.538333-1-gladkov.alexey@gmail.com> <20200210150519.538333-8-gladkov.alexey@gmail.com> <87v9odlxbr.fsf@x220.int.ebiederm.org> <20200212144921.sykucj4mekcziicz@comp-core-i7-2640m-0182e6> <87tv3vkg1a.fsf@x220.int.ebiederm.org> <87v9obipk9.fsf@x220.int.ebiederm.org> <20200212200335.GO23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Feb 12, 2020 at 12:35:04PM -0800, Linus Torvalds wrote: > On Wed, Feb 12, 2020 at 12:03 PM Al Viro wrote: > > > > What's to prevent racing with fs shutdown while you are doing the second part? > > I was thinking that only the proc_flush_task() code would do this. > > And that holds a ref to the vfsmount through upid->ns. > > So I wasn't suggesting doing this in general - just splitting up the > implementation of d_invalidate() so that proc_flush_task_mnt() could > delay the complex part to after having traversed the RCU-protected > list. > > But hey - I missed this part of the problem originally, so maybe I'm > just missing something else this time. Wouldn't be the first time. Wait, I thought the whole point of that had been to allow multiple procfs instances for the same userns? Confused...