From patchwork Sat May 7 08:45:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chen Zhongjin X-Patchwork-Id: 570939 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 5D1D1C433EF for ; Sat, 7 May 2022 08:46:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1446135AbiEGIuW (ORCPT ); Sat, 7 May 2022 04:50:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358391AbiEGIuU (ORCPT ); Sat, 7 May 2022 04:50:20 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E97C48380; Sat, 7 May 2022 01:46:34 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KwLWx0db2zXdkZ; Sat, 7 May 2022 16:41:49 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500022.china.huawei.com (7.185.36.162) 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 16:46:32 +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; Sat, 7 May 2022 16:46:31 +0800 From: Chen Zhongjin To: , , , CC: , , , , , , , Subject: [PATCH 5.10 v3] locking/csd_lock: fix csdlock_debug cause arm64 boot panic Date: Sat, 7 May 2022 16:45:10 +0800 Message-ID: <20220507084510.14761-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.36] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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 v2 -> v3: Add module name in title 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);