From nobody Sun May 10 23:26:39 2026 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 D3F52C433EF for ; Thu, 21 Apr 2022 03:40:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383981AbiDUDnN (ORCPT ); Wed, 20 Apr 2022 23:43:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242476AbiDUDnL (ORCPT ); Wed, 20 Apr 2022 23:43:11 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 503CA9FE6 for ; Wed, 20 Apr 2022 20:40:22 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KkNbK5nXkzhY1t; Thu, 21 Apr 2022 11:40:13 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 21 Apr 2022 11:40:20 +0800 Received: from ubuntu1804.huawei.com (10.67.175.36) 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; Thu, 21 Apr 2022 11:40:20 +0800 From: Chen Zhongjin To: , CC: , , , , , Subject: [PATCH 5.10] fix csdlock_debug cause arm64 boot panic Date: Thu, 21 Apr 2022 11:39:14 +0800 Message-ID: <20220421033914.217622-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.36] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) 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 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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=3Dy CONFIG_SPARSEMEM_VMEMMAP=3Dn 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=3Dn, __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 --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index 65a630f62363..1ce64de460d0 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -176,7 +176,7 @@ static int __init csdlock_debug(char *str) =20 return 0; } -early_param("csdlock_debug", csdlock_debug); +__setup("csdlock_debug=3D", csdlock_debug); =20 static DEFINE_PER_CPU(call_single_data_t *, cur_csd); static DEFINE_PER_CPU(smp_call_func_t, cur_csd_func); --=20 2.17.1