Messages in this thread |  | | Date | Thu, 23 Oct 2014 07:45:44 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [PATCH v2] memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node() |
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(2014/10/23 4:02), Toshi Kani wrote: > On Wed, 2014-10-22 at 16:51 +0900, Yasuaki Ishimatsu wrote: >> 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() 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: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> > > Thanks for the update. It looks good. >
> Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Thank you for your review.
Thanks, Yasuaki Ishimatasu
> > -Toshi > > >
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