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=-3.8 required=3.0 tests=BAYES_00, 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 574A8C433DF for ; Fri, 9 Oct 2020 08:06:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0345722227 for ; Fri, 9 Oct 2020 08:06:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732546AbgJIIGS (ORCPT ); Fri, 9 Oct 2020 04:06:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50616 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732337AbgJIIGS (ORCPT ); Fri, 9 Oct 2020 04:06:18 -0400 Received: from sipsolutions.net (s3.sipsolutions.net [IPv6:2a01:4f8:191:4433::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F37F2C0613D2; Fri, 9 Oct 2020 01:06:17 -0700 (PDT) Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94) (envelope-from ) id 1kQnPr-00296a-Hh; Fri, 09 Oct 2020 10:06:15 +0200 Message-ID: Subject: Re: [CRAZY-RFF] debugfs: track open files and release on remove From: Johannes Berg To: Greg KH Cc: linux-kernel@vger.kernel.org, nstange@suse.de, ap420073@gmail.com, David.Laight@aculab.com, netdev@vger.kernel.org, linux-wireless@vger.kernel.org, rafael@kernel.org Date: Fri, 09 Oct 2020 10:06:14 +0200 In-Reply-To: <20201009080355.GA398994@kroah.com> References: <87v9fkgf4i.fsf@suse.de> <20201009095306.0d87c3aa13db.Ib3a7019bff15bb6308f6d259473a1648312a4680@changeid> <20201009080355.GA398994@kroah.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, 2020-10-09 at 10:03 +0200, Greg KH wrote: > For lots of debugfs files, .owner should already be set, if you use the > DEFINE_SIMPLE_ATTRIBUTE() or DEFINE_DEBUGFS_ATTRIBUTE() macros. > > But yes, not all. Right. You didn't see the original thread: https://lore.kernel.org/netdev/20201008155048.17679-1-ap420073@gmail.com/ > I thought the proxy-ops stuff was supposed to fix this issue already. > Why isn't it, what is broken in them that causes this to still crash? Well exactly what I described - the proxy_fops *release* doesn't get proxied, since we don't have any knowledge of the open files (without this patch) when the proxy_fops are redirected to nothing when a file is removed. Nicolai also discussed it a bit here: https://lore.kernel.org/netdev/87v9fkgf4i.fsf@suse.de/ > And of course, removing kernel modules is never a guaranteed operation, > nor is it anything that ever happens automatically, so is this really an > issue? :) :) We used to say the proxy_fops weren't needed and it wasn't an issue, and then still implemented it. Dunno. I'm not really too concerned about it myself, only root can hold the files open and remove modules ... johannes