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=unavailable 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 2736FC433DF for ; Mon, 6 Jul 2020 01:20:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01D822053B for ; Mon, 6 Jul 2020 01:20:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728708AbgGFBUO (ORCPT ); Sun, 5 Jul 2020 21:20:14 -0400 Received: from foss.arm.com ([217.140.110.172]:45850 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728509AbgGFBUL (ORCPT ); Sun, 5 Jul 2020 21:20:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 58B1F101E; Sun, 5 Jul 2020 18:20:11 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.212.213]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id F1BFB3F718; Sun, 5 Jul 2020 18:20:07 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon Cc: Andrew Morton , Mike Rapoport , Baoquan He , Chuhong Yuan , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kaly Xin , Jia He Subject: [PATCH 2/3] mm/memory_hotplug: harden try_offline_node against bogus nid Date: Mon, 6 Jul 2020 09:19:46 +0800 Message-Id: <20200706011947.184166-3-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200706011947.184166-1-justin.he@arm.com> References: <20200706011947.184166-1-justin.he@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When testing the remove_memory path of dax pmem, there will be a panic with call trace: try_remove_memory+0x84/0x170 remove_memory+0x38/0x58 dev_dax_kmem_remove+0x3c/0x84 [kmem] device_release_driver_internal+0xfc/0x1c8 device_release_driver+0x28/0x38 bus_remove_device+0xd4/0x158 device_del+0x160/0x3a0 unregister_dev_dax+0x30/0x68 devm_action_release+0x20/0x30 release_nodes+0x150/0x240 devres_release_all+0x6c/0x1d0 device_release_driver_internal+0x10c/0x1c8 driver_detach+0xac/0x170 bus_remove_driver+0x64/0x130 driver_unregister+0x34/0x60 dax_pmem_exit+0x14/0xffc4 [dax_pmem] __arm64_sys_delete_module+0x18c/0x2d0 el0_svc_common.constprop.2+0x78/0x168 do_el0_svc+0x34/0xa0 el0_sync_handler+0xe0/0x188 el0_sync+0x164/0x180 It is caused by the bogus nid (-1). Although the root cause is pmem dax translates from pxm to node_id incorrectly due to numa_off, it is worth hardening the codes in try_offline_node(), quiting if !pgdat. Signed-off-by: Jia He --- mm/memory_hotplug.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index da374cd3d45b..e1e290577b45 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1680,6 +1680,9 @@ void try_offline_node(int nid) pg_data_t *pgdat = NODE_DATA(nid); int rc; + if (WARN_ON(!pgdat)) + return; + /* * If the node still spans pages (especially ZONE_DEVICE), don't * offline it. A node spans memory after move_pfn_range_to_zone(), -- 2.17.1