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=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 6DDD7C433B4 for ; Wed, 7 Apr 2021 20:18:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4200B61158 for ; Wed, 7 Apr 2021 20:18:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234693AbhDGUSL (ORCPT ); Wed, 7 Apr 2021 16:18:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30345 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232929AbhDGUSJ (ORCPT ); Wed, 7 Apr 2021 16:18:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617826678; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=aQknNtkrD3GHg+E4N/uth2eOy0S3ZwiKhVq/VQGmwhM=; b=MzWFZc7DTswGljIlCW6cGoU9iHl4xLVC0pKWF4IA1niBW469xcJAp23wlHvE2IL7/mtIqL zhuBi0veWGEHGJgftarbkivJa/zH0i/hqWjuijquPxDk0o0q5upuGsXjxTI7p/rQVLvgKX Na20vTpkWdsSFgjcbtq/9pBiHR3cZVs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-249-_Ff8sjcSNDalXMd_Kh6KAw-1; Wed, 07 Apr 2021 16:17:53 -0400 X-MC-Unique: _Ff8sjcSNDalXMd_Kh6KAw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D7A07881276; Wed, 7 Apr 2021 20:17:50 +0000 (UTC) Received: from treble (ovpn-119-205.rdu2.redhat.com [10.10.119.205]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6A275610AE; Wed, 7 Apr 2021 20:17:48 +0000 (UTC) Date: Wed, 7 Apr 2021 15:17:46 -0500 From: Josh Poimboeuf To: Greg KH Cc: Luis Chamberlain , Minchan Kim , keescook@chromium.org, dhowells@redhat.com, hch@infradead.org, mbenes@suse.com, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt , Peter Zijlstra , Jessica Yu , Thomas Gleixner , Linus Torvalds Subject: Re: [PATCH 1/2] zram: fix crashes due to use of cpu hotplug multistate Message-ID: <20210407201746.ueijmegmpbyq5quv@treble> References: <20210310212128.GR4332@42.do-not-panic.com> <20210312183238.GW4332@42.do-not-panic.com> <20210319190924.GK4332@42.do-not-panic.com> <20210322204156.GM4332@42.do-not-panic.com> <20210401235925.GR4332@42.do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Apr 02, 2021 at 09:54:12AM +0200, Greg KH wrote: > On Thu, Apr 01, 2021 at 11:59:25PM +0000, Luis Chamberlain wrote: > > As for the syfs deadlock possible with drivers, this fixes it in a generic way: > > > > commit fac43d8025727a74f80a183cc5eb74ed902a5d14 > > Author: Luis Chamberlain > > Date: Sat Mar 27 14:58:15 2021 +0000 > > > > sysfs: add optional module_owner to attribute > > > > This is needed as otherwise the owner of the attribute > > or group read/store might have a shared lock used on driver removal, > > and deadlock if we race with driver removal. > > > > Signed-off-by: Luis Chamberlain > > No, please no. Module removal is a "best effort", if the system dies > when it happens, that's on you. I am not willing to expend extra energy > and maintance of core things like sysfs for stuff like this that does > not matter in any system other than a developer's box. So I mentioned this on IRC, and some folks were surprised to hear that module unloading is unsupported and is just a development aid. Is this stance documented anywhere? If we really believe this to be true, we should make rmmod taint the kernel. -- Josh