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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 39F9AC43331 for ; Wed, 13 Nov 2019 09:30:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EB79222D0 for ; Wed, 13 Nov 2019 09:30:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727387AbfKMJaO (ORCPT ); Wed, 13 Nov 2019 04:30:14 -0500 Received: from relay.sw.ru ([185.231.240.75]:39206 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727074AbfKMJaN (ORCPT ); Wed, 13 Nov 2019 04:30:13 -0500 Received: from finist_cl7.qa.sw.ru ([10.94.4.83] helo=finist-ce7.sw.ru) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1iUoyF-00062s-7g; Wed, 13 Nov 2019 12:29:51 +0300 From: Konstantin Khorenko To: Jessica Yu , Prarit Bhargava , Barret Rhoden Cc: Konstantin Khorenko , Andrey Ryabinin , linux-kernel@vger.kernel.org, David Arcari , Heiko Carstens Subject: [PATCH 1/1] kernel/module.c: wakeup processes in module_wq on module unload Date: Wed, 13 Nov 2019 12:29:50 +0300 Message-Id: <20191113092950.15556-2-khorenko@virtuozzo.com> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20191113092950.15556-1-khorenko@virtuozzo.com> References: <20191113092950.15556-1-khorenko@virtuozzo.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fix the race between load and unload a kernel module. sys_delete_module() try_stop_module() mod->state = _GOING add_unformed_module() old = find_module_all() (old->state == _GOING => wait_event_interruptible()) During pre-condition finished_loading() rets 0 schedule() (never gets waken up later) free_module() mod->state = _UNFORMED list_del_rcu(&mod->list) (dels mod from "modules" list) return The race above leads to modprobe hanging forever on loading a module. Error paths on loading module call wake_up_all(&module_wq) after freeing module, so let's do the same on straight module unload. Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading") Signed-off-by: Konstantin Khorenko --- kernel/module.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/module.c b/kernel/module.c index ff2d7359a418..cb09a5f37a5f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1033,6 +1033,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); free_module(mod); + /* someone could wait for the module in add_unformed_module() */ + wake_up_all(&module_wq); return 0; out: mutex_unlock(&module_mutex); -- 2.15.1