• Yasuaki Ishimatsu's avatar
    memory-hotplug: clear pgdat which is allocated by bootmem in try_offline_node() · 35dca71c
    Yasuaki Ishimatsu authored
    When hot adding the same memory after hot removal, 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
        hotadd_new_pgdat+0x90/0x110
        add_memory+0xd4/0x200
        acpi_memory_device_add+0x1aa/0x289
        acpi_bus_attach+0xfd/0x204
        acpi_bus_attach+0x178/0x204
        acpi_bus_scan+0x6a/0x90
        acpi_device_hotplug+0xe8/0x418
        acpi_hotplug_work_fn+0x1f/0x2b
        process_one_work+0x14e/0x3f0
        worker_thread+0x11b/0x510
        kthread+0xe1/0x100
        ret_from_fork+0x7c/0xb0
    
    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() checks 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: default avatarYasuaki 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>
    Reviewed-by: default avatarToshi Kani <toshi.kani@hp.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: David Rientjes <rientjes@google.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    35dca71c
memory_hotplug.c 50.7 KB