From: Toshi Kani <toshi.kani@hp.com>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, zhenzhang.zhang@huawei.com,
wangnan0@huawei.com, tangchen@cn.fujitsu.com,
dave.hansen@intel.com, rientjes@google.com
Subject: Re: [PATCH v2] memory-hotplug: Clear pgdat which is allocated by bootmem in try_offline_node()
Date: Wed, 22 Oct 2014 13:02:11 -0600 [thread overview]
Message-ID: <1414004531.12798.27.camel@misato.fc.hp.com> (raw)
In-Reply-To: <54476215.3010006@jp.fujitsu.com>
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>
-Toshi
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next prev parent reply other threads:[~2014-10-22 19:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 7:51 Yasuaki Ishimatsu
2014-10-22 19:02 ` Toshi Kani [this message]
2014-10-22 22:45 ` Yasuaki Ishimatsu
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