Messages in this thread Patch in this message | | | Date | Mon, 20 Oct 2014 19:05:41 +0900 | From | Yasuaki Ishimatsu <> | Subject | [PATCH] memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node() |
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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 <isimatu.yasuaki@jp.fujitsu.com> CC: Zhang Zhen <zhenzhang.zhang@huawei.com> CC: Wang Nan <wangnan0@huawei.com> CC: Tang Chen <tangchen@cn.fujitsu.com> CC: Toshi Kani <toshi.kani@hp.com> CC: Dave Hansen <dave.hansen@intel.com> CC: David Rientjes <rientjes@google.com>
--- 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
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