Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753517AbaJTKGt (ORCPT ); Mon, 20 Oct 2014 06:06:49 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:41369 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753333AbaJTKGs (ORCPT ); Mon, 20 Oct 2014 06:06:48 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v2.0.1 X-SHieldMailCheckerPolicyVersion: FJ-ISEC-20120718-3 Message-ID: <5444DE75.6010206@jp.fujitsu.com> Date: Mon, 20 Oct 2014 19:05:41 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: , , CC: , , , , , Subject: [PATCH] memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node() Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit X-SecurityPolicyCheck-GC: OK by FENCE-Mail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When hot adding the same memory after hot removing a memory, the following messages are shown: WARNING: CPU: 20 PID: 6 at mm/page_alloc.c:4968 free_area_init_node+0x3fe/0x426() ... Call Trace: [<...>] dump_stack+0x46/0x58 [<...>] warn_slowpath_common+0x81/0xa0 [<...>] warn_slowpath_null+0x1a/0x20 [<...>] free_area_init_node+0x3fe/0x426 [<...>] ? up+0x32/0x50 [<...>] hotadd_new_pgdat+0x90/0x110 [<...>] add_memory+0xd4/0x200 [<...>] acpi_memory_device_add+0x1aa/0x289 [<...>] acpi_bus_attach+0xfd/0x204 [<...>] ? device_register+0x1e/0x30 [<...>] acpi_bus_attach+0x178/0x204 [<...>] acpi_bus_scan+0x6a/0x90 [<...>] ? acpi_bus_get_status+0x2d/0x5f [<...>] acpi_device_hotplug+0xe8/0x418 [<...>] acpi_hotplug_work_fn+0x1f/0x2b [<...>] process_one_work+0x14e/0x3f0 [<...>] worker_thread+0x11b/0x510 [<...>] ? rescuer_thread+0x350/0x350 [<...>] kthread+0xe1/0x100 [<...>] ? kthread_create_on_node+0x1b0/0x1b0 [<...>] ret_from_fork+0x7c/0xb0 [<...>] ? kthread_create_on_node+0x1b0/0x1b0 The detaled explanation is as follows: When hot removing memory, pgdat is set to 0 in try_offline_node(). But if the pgdat is allocated by bootmem allocator, the clearing step is skipped. And when hot adding the same memory, the uninitialized pgdat is reused. But free_area_init_node() chacks wether pgdat is set to zero. As a result, free_area_init_node() hits WARN_ON(). This patch clears pgdat which is allocated by bootmem allocator in try_offline_node(). Signed-off-by: Yasuaki Ishimatsu CC: Zhang Zhen CC: Wang Nan CC: Tang Chen CC: Toshi Kani CC: Dave Hansen CC: David Rientjes --- mm/memory_hotplug.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 29d8693..7649f7c 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1943,7 +1943,7 @@ void try_offline_node(int nid) if (!PageSlab(pgdat_page) && !PageCompound(pgdat_page)) /* node data is allocated from boot memory */ - return; + goto out; /* free waittable in each zone */ for (i = 0; i < MAX_NR_ZONES; i++) { @@ -1957,6 +1957,7 @@ void try_offline_node(int nid) vfree(zone->wait_table); } +out: /* * Since there is no way to guarentee the address of pgdat/zone is not * on stack of any kernel threads or used by other kernel objects -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/