From patchwork Thu Jun 17 07:51:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kefeng Wang X-Patchwork-Id: 12326989 X-Patchwork-Delegate: kuba@kernel.org 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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 03DDDC48BE5 for ; Thu, 17 Jun 2021 07:51:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E17B1613DF for ; Thu, 17 Jun 2021 07:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230215AbhFQHyC (ORCPT ); Thu, 17 Jun 2021 03:54:02 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:4829 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229712AbhFQHyB (ORCPT ); Thu, 17 Jun 2021 03:54:01 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4G5Df15mp4zXg6h; Thu, 17 Jun 2021 15:46:49 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 17 Jun 2021 15:51:52 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 17 Jun 2021 15:51:51 +0800 From: Kefeng Wang Subject: [BUG] Crash after module unload if it use DO_ONCE mechanism To: "David S. Miller" , Hannes Frederic Sowa , Alexei Starovoitov , "Eric Dumazet" , Jakub Kicinski , "Linux Kernel Network Developers" , "linux-kernel@vger.kernel.org List" Message-ID: Date: Thu, 17 Jun 2021 15:51:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 Content-Language: en-US X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi all, We met a crash[3] after module unload if it uses DO_ONCE mechanism, also we could reproduce by the demo module[1] and the hack patch[2]. The DO_ONCE mechanism could be use directly(eg, testmgr.c), and there are some macro which is used by lots of net drivers, "prandom_init_once" "get_random_once/get_random_once_wait" "net_get_random_once/net_get_random_once_wait" The analysis of crash is as follows, init_module get_random_once DO_ONCE DEFINE_STATIC_KEY_TRUE(___once_key); __do_once_done once_disable_jump(once_key); INIT_WORK(&w->work, once_deferred); struct once_work *w; w->key = key; schedule_work(&w->work); cleanup_module *the key is destroy* process_one_work once_deferred BUG_ON(!static_key_enabled(work->key)); static_key_count((struct static_key *)x) //*access key, crash* I can't find a good way to fix the issue, any suggestion? Thanks. [1] test module static int test; int init_module(void) { pr_info("Hello\n"); get_random_once(&test, sizeof(int)); return 0; } void cleanup_module(void) { pr_info("Bye %x!\n", test); } [2] hack to add some delay [3] crash log [ 253.560859] Hello [ 253.562851] Bye 92bbb335! [ 261.585813] Unable to handle kernel paging request at virtual address ffff000001293018 [ 261.585815] Mem abort info: [ 261.585816] ESR = 0x96000007 [ 261.585817] Exception class = DABT (current EL), IL = 32 bits [ 261.585818] SET = 0, FnV = 0 [ 261.585818] EA = 0, S1PTW = 0 [ 261.585819] Data abort info: [ 261.585820] ISV = 0, ISS = 0x00000007 [ 261.585821] CM = 0, WnR = 0 [ 261.585822] swapper pgtable: 4k pages, 48-bit VAs, pgdp = 00000000e45c016c [ 261.585823] [ffff000001293018] pgd=000000023fffe003, pud=000000023354b003, pmd=00000001d4099003, pte=0000000000000000 [ 261.585827] Internal error: Oops: 96000007 [#1] SMP [ 261.586458] Process kworker/25:1 (pid: 291, stack limit = 0xffff0000841b0000) [ 261.586880] CPU: 25 PID: 291 Comm: kworker/25:1 Kdump: loaded Tainted: P W OE 4.19.90+ #14 [ 261.587415] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 [ 261.587819] Workqueue: events once_deferred [ 261.588062] pstate: 60c00005 (nZCv daif +PAN +UAO) [ 261.588341] pc : static_key_count+0x18/0x30 [ 261.588584] lr : once_deferred+0x30/0x80 [ 261.588810] sp : ffff0000841b3d70 [ 261.589000] x29: ffff0000841b3d70 x28: 0000000000000000 [ 261.589308] x27: 0000000000000000 x26: ffff00008131f330 [ 261.589615] x25: 0000000000000000 x24: ffff8001defd1c08 [ 261.590025] x23: 0000000000000000 x22: ffff8001ff4d3000 [ 261.590414] x21: ffff8001ff4cee80 x20: ffff8001f3bbd100 [ 261.590868] x19: ffff000001293018 x18: ffffffffffffffff [ 261.591254] x17: 0000000000000000 x16: 0000000000000000 [ 261.591638] x15: ffff0000812fa748 x14: ffff0000814f1d50 [ 261.592026] x13: ffff0000814f1996 x12: ffffffffffffffac [ 261.592409] x11: 0000000000000000 x10: 0000000000000b80 [ 261.592794] x9 : ffff0000841b3bf0 x8 : 3535303030303030 [ 261.593179] x7 : 303078302079656b x6 : ffff0000814f0f80 [ 261.593564] x5 : 00ffffffffffffff x4 : 0000000000000000 [ 261.593978] x3 : 0000000000000000 x2 : 173087582665d800 [ 261.594362] x1 : 0000000000000000 x0 : ffff00008055a888 [ 261.594748] Call trace: [ 261.594928] static_key_count+0x18/0x30 [ 261.595207] once_deferred+0x30/0x80 [ 261.595469] process_one_work+0x1b8/0x458 [ 261.595762] worker_thread+0x158/0x498 [ 261.596034] kthread+0x134/0x138 [ 261.596271] ret_from_fork+0x10/0x18 [ 261.596531] Code: f9000bf3 aa0003f3 aa1e03e0 d503201f (b9400260) diff --git a/lib/once.c b/lib/once.c index 8b7d6235217e..b56b8ced4bab 100644 --- a/lib/once.c +++ b/lib/once.c @@ -14,6 +14,7 @@ static void once_deferred(struct work_struct *w) struct once_work *work; work = container_of(w, struct once_work, work); + msleep(8000); BUG_ON(!static_key_enabled(work->key)); static_branch_disable(work->key); kfree(work);