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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 D2177C10F13 for ; Mon, 8 Apr 2019 14:19:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF4AA21473 for ; Mon, 8 Apr 2019 14:19:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726763AbfDHOTy (ORCPT ); Mon, 8 Apr 2019 10:19:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30939 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726349AbfDHOTy (ORCPT ); Mon, 8 Apr 2019 10:19:54 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E03DC308FC5E; Mon, 8 Apr 2019 14:19:53 +0000 (UTC) Received: from prarit.bos.redhat.com (prarit-guest.khw1.lab.eng.bos.redhat.com [10.16.200.63]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5EF9B60472; Mon, 8 Apr 2019 14:19:53 +0000 (UTC) Subject: Re: [PATCH] modules: Only return -EEXIST for modules that have finished loading To: linux-kernel@vger.kernel.org Cc: cavery@redhat.com, Jessica Yu References: <20190402133916.13513-1-prarit@redhat.com> From: Prarit Bhargava Message-ID: Date: Mon, 8 Apr 2019 10:19:52 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190402133916.13513-1-prarit@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 08 Apr 2019 14:19:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jessica? ping? P. On 4/2/19 9:39 AM, Prarit Bhargava wrote: > Microsoft HyperV disables the X86_FEATURE_SMCA bit on AMD systems, and > linux guests boot with repeated errors: > > amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2) > amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2) > amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2) > amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2) > amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2) > amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2) > > The warnings occur because the module code erroneously returns -EEXIST > for modules that have failed to load and are in the process of being > removed from the module list. > > module amd64_edac_mod has a dependency on module edac_mce_amd. Using > modules.dep, systemd will load edac_mce_amd for every request of > amd64_edac_mod. When the edac_mce_amd module loads, the module has > state MODULE_STATE_UNFORMED and once the module load fails and the state > becomes MODULE_STATE_GOING. Another request for edac_mce_amd module > executes and add_unformed_module() will erroneously return -EEXIST even > though the previous instance of edac_mce_amd has MODULE_STATE_GOING. > Upon receiving -EEXIST, systemd attempts to load amd64_edac_mod, which > fails because of unknown symbols from edac_mce_amd. > > add_unformed_module() must wait to return for any case other than > MODULE_STATE_LIVE to prevent a race between multiple loads of > dependent modules. > > Signed-off-by: Prarit Bhargava > Reported-by: Cathy Avery > Cc: Jessica Yu > --- > kernel/module.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 0b9aa8ab89f0..e8c1de2ab4e1 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -3566,8 +3566,7 @@ static int add_unformed_module(struct module *mod) > mutex_lock(&module_mutex); > old = find_module_all(mod->name, strlen(mod->name), true); > if (old != NULL) { > - if (old->state == MODULE_STATE_COMING > - || old->state == MODULE_STATE_UNFORMED) { > + if (old->state != MODULE_STATE_LIVE) { > /* Wait in case it fails to load. */ > mutex_unlock(&module_mutex); > err = wait_event_interruptible(module_wq, >