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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 3B191C433B4 for ; Wed, 7 Apr 2021 16:49:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0403A6120E for ; Wed, 7 Apr 2021 16:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243342AbhDGQuG (ORCPT ); Wed, 7 Apr 2021 12:50:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241671AbhDGQuF (ORCPT ); Wed, 7 Apr 2021 12:50:05 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC0FBC061756; Wed, 7 Apr 2021 09:49:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=2njEr9ZUa7y9HL1hJAt9pr7cUOGTLQlkQmxjlTPcmNU=; b=TrCYgYVMGO2a+5h6D17m8iexku mApqxwXIBwPoLfOBB2PwEiYwbTdSCEvwmlwle9wv0CZzwQugywD6bAsCPSkkVArolQhmMdydbFRyq NkSSb3VQkiyv9si8u79pozGy+TVO/UytP2zdqDUtrKQdA+2KBR41N3TCMJgN4VnFmBCJ55A69hcXN 1scFbLa1trXAgbhZXELrxYOxvT9P8jCK4LqOBUVtvoJTnF6u1kFfehiZvvbdNYNg/EKJLyijjN5SC 9vOMRpqdnOZuVX7wO5AF92cyNx6j9D1TtjMd2dUmoaRivlEUtuygzIedDwB4AFeXaSuuSUmRFWIZE I/jrfcDQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lUBLY-00EmfR-8s; Wed, 07 Apr 2021 16:48:20 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 956E43001FB; Wed, 7 Apr 2021 18:48:03 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7EC0F23D3AF86; Wed, 7 Apr 2021 18:48:03 +0200 (CEST) Date: Wed, 7 Apr 2021 18:48:03 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Miroslav Benes , Greg KH , Luis Chamberlain , mbenes@suse.com, Minchan Kim , keescook@chromium.org, dhowells@redhat.com, hch@infradead.org, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Jessica Yu Subject: Re: [PATCH 1/2] zram: fix crashes due to use of cpu hotplug multistate Message-ID: References: <20210401235925.GR4332@42.do-not-panic.com> <20210402183016.GU4332@42.do-not-panic.com> <20210406003152.GZ4332@42.do-not-panic.com> <20210406155423.t7dagp24bupudv3p@treble> <20210407153031.m4gg3rsgwlr432ba@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210407153031.m4gg3rsgwlr432ba@treble> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Apr 07, 2021 at 10:30:31AM -0500, Josh Poimboeuf wrote: > On Wed, Apr 07, 2021 at 04:09:44PM +0200, Peter Zijlstra wrote: > > On Tue, Apr 06, 2021 at 10:54:23AM -0500, Josh Poimboeuf wrote: > > > > > Same for Red Hat. Unloading livepatch modules seems to work fine, but > > > isn't officially supported. > > > > > > That said, if rmmod is just considered a development aid, and we're > > > going to be ignoring bugs, we should make it official with a new > > > TAINT_RMMOD. > > > > Another option would be to have live-patch modules leak a module > > reference by default, except when some debug sysctl is set or something. > > Then only those LP modules loaded while the sysctl is set to 'YOLO' can > > be unloaded. > > The issue is broader than just live patching. > > My suggestion was that if we aren't going to fix bugs in kernel module > unloading, then unloading modules shouldn't be supported, and should > taint the kernel. Hold up, what? However much I dislike modules (and that is lots), if you don't want to support rmmod, you have to leak a reference to self in init. Barring that you get to fix any and all unload bugs.