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Message-ID: <5591F862.7030706@jp.fujitsu.com>
Date: Tue, 30 Jun 2015 11:01:06 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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Subject: Re: [RFC v2 PATCH 7/8] mm: add the buddy system interface
References: <558E084A.60900@huawei.com> <558E0A28.6060607@huawei.com> <3908561D78D1C84285E8C5FCA982C28F32AA124A@ORSMSX114.amr.corp.intel.com> <5591EA50.1000000@jp.fujitsu.com> <5591F18E.3060504@huawei.com>
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To: Xishi Qiu <qiuxishi@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>, Andrew Morton <akpm@linux-foundation.org>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>, Hanjun Guo <guohanjun@huawei.com>, Xiexiuqi <xiexiuqi@huawei.com>, "leon@leon.nu" <leon@leon.nu>, "Hansen, Dave" <dave.hansen@intel.com>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@suse.de>, Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>

On 2015/06/30 10:31, Xishi Qiu wrote:
> On 2015/6/30 9:01, Kamezawa Hiroyuki wrote:
>
>> On 2015/06/30 8:11, Luck, Tony wrote:
>>>> @@ -814,7 +814,7 @@ int __init_memblock memblock_clear_hotplug(phys_addr_t base, phys_addr_t size)
>>>>     */
>>>>    int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
>>>>    {
>>>> -    system_has_some_mirror = true;
>>>> +    static_key_slow_inc(&system_has_mirror);
>>>>
>>>>        return memblock_setclr_flag(base, size, 1, MEMBLOCK_MIRROR);
>>>>    }
>>>
>>> This generates some WARN_ON noise when called from efi_find_mirror():
>>>
>>
>> It seems jump_label_init() is called after memory initialization. (init/main.c::start_kernel())
>> So, it may be difficut to use static_key function for our purpose because
>> kernel memory allocation may occur before jump_label is ready.
>>
>> Thanks,
>> -Kame
>>
>
> Hi Kame,
>
> How about like this? Use static bool in bootmem, and use jump label in buddy system.
> This means we use two variable to do it.
>

I think it can be done but it should be done in separated patch with enough comment/changelog.

Thanks,
-Kame



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