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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 992ACC433EF for ; Sat, 7 May 2022 07:01:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1445957AbiEGHE5 (ORCPT ); Sat, 7 May 2022 03:04:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46416 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239988AbiEGHEt (ORCPT ); Sat, 7 May 2022 03:04:49 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7360142EF0 for ; Sat, 7 May 2022 00:01:01 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KwJGy6pqPzhYTq; Sat, 7 May 2022 15:00:26 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 7 May 2022 15:00:59 +0800 Received: from [127.0.0.1] (10.67.108.67) by dggpemm500013.china.huawei.com (7.185.36.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 7 May 2022 15:00:59 +0800 Message-ID: <2438f9e2-1e8e-56ce-b5cd-e4f44d9a03db@huawei.com> Date: Sat, 7 May 2022 15:00:59 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 5.10 v2] fix csdlock_debug cause arm64 boot panic Content-Language: en-US To: , , CC: , , , , References: <20220421071129.151794-1-chenzhongjin@huawei.com> From: Chen Zhongjin In-Reply-To: <20220421071129.151794-1-chenzhongjin@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.108.67] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping for review. On 2022/4/21 15:11, Chen Zhongjin wrote: > csdlock_debug is a early_param to enable csd_lock_wait > feature. > > It uses static_branch_enable in early_param which triggers > a panic on arm64 with config: > CONFIG_SPARSEMEM=y > CONFIG_SPARSEMEM_VMEMMAP=n > > The log shows: > Unable to handle kernel NULL pointer dereference at > virtual address ", '0' , " > ... > Call trace: > __aarch64_insn_write+0x9c/0x18c > ... > static_key_enable+0x1c/0x30 > csdlock_debug+0x4c/0x78 > do_early_param+0x9c/0xcc > parse_args+0x26c/0x3a8 > parse_early_options+0x34/0x40 > parse_early_param+0x80/0xa4 > setup_arch+0x150/0x6c8 > start_kernel+0x8c/0x720 > ... > Kernel panic - not syncing: Oops: Fatal exception > > Call trace inside __aarch64_insn_write: > __nr_to_section > __pfn_to_page > phys_to_page > patch_map > __aarch64_insn_write > > Here, with CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section returns > NULL and makes the NULL dereference because mem_section is > initialized in sparse_init after parse_early_param stage. > > So, static_branch_enable shouldn't be used inside early_param. > To avoid this, I changed it to __setup and fixed this. > > Reported-by: Chen jingwen > Signed-off-by: Chen Zhongjin > --- > Change v1 -> v2: > Fix return 1 for __setup > --- > kernel/smp.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/smp.c b/kernel/smp.c > index 65a630f62363..381eb15cd28f 100644 > --- a/kernel/smp.c > +++ b/kernel/smp.c > @@ -174,9 +174,9 @@ static int __init csdlock_debug(char *str) > if (val) > static_branch_enable(&csdlock_debug_enabled); > > - return 0; > + return 1; > } > -early_param("csdlock_debug", csdlock_debug); > +__setup("csdlock_debug=", csdlock_debug); > > static DEFINE_PER_CPU(call_single_data_t *, cur_csd); > static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func);