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From: "Shi, Yang" <yang.shi@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linaro-kernel@lists.linaro.org
Subject: Re: [PATCH] mm: use early_pfn_to_nid in register_page_bootmem_info_node
Date: Wed, 25 May 2016 15:36:48 -0700	[thread overview]
Message-ID: <03d44563-3860-052b-1c49-e81208bdd697@linaro.org> (raw)
In-Reply-To: <20160525152319.fa87b4cc0b8326fef89a1b92@linux-foundation.org>

On 5/25/2016 3:23 PM, Andrew Morton wrote:
> On Wed, 25 May 2016 14:00:07 -0700 Yang Shi <yang.shi@linaro.org> wrote:
>
>> register_page_bootmem_info_node() is invoked in mem_init(), so it will be
>> called before page_alloc_init_late() if CONFIG_DEFERRED_STRUCT_PAGE_INIT
>> is enabled. But, pfn_to_nid() depends on memmap which won't be fully setup
>> until page_alloc_init_late() is done, so replace pfn_to_nid() by
>> early_pfn_to_nid().
>
> What are the runtime effects of this fix?

I didn't experience any problem without the fix. During working on the 
page_ext_init() fix (replace to early_pfn_to_nid()), I added printk 
before each pfn_to_nid() calls to check which one might be called before 
page_alloc_init_late(), then this one is caught.

 From the code perspective, it sounds not right since 
register_page_bootmem_info_section() may miss some pfns when 
CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, just like the problem 
happened in page_ext_init().

Thanks,
Yang


>

WARNING: multiple messages have this Message-ID (diff)
From: "Shi, Yang" <yang.shi@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linaro-kernel@lists.linaro.org
Subject: Re: [PATCH] mm: use early_pfn_to_nid in register_page_bootmem_info_node
Date: Wed, 25 May 2016 15:36:48 -0700	[thread overview]
Message-ID: <03d44563-3860-052b-1c49-e81208bdd697@linaro.org> (raw)
In-Reply-To: <20160525152319.fa87b4cc0b8326fef89a1b92@linux-foundation.org>

On 5/25/2016 3:23 PM, Andrew Morton wrote:
> On Wed, 25 May 2016 14:00:07 -0700 Yang Shi <yang.shi@linaro.org> wrote:
>
>> register_page_bootmem_info_node() is invoked in mem_init(), so it will be
>> called before page_alloc_init_late() if CONFIG_DEFERRED_STRUCT_PAGE_INIT
>> is enabled. But, pfn_to_nid() depends on memmap which won't be fully setup
>> until page_alloc_init_late() is done, so replace pfn_to_nid() by
>> early_pfn_to_nid().
>
> What are the runtime effects of this fix?

I didn't experience any problem without the fix. During working on the 
page_ext_init() fix (replace to early_pfn_to_nid()), I added printk 
before each pfn_to_nid() calls to check which one might be called before 
page_alloc_init_late(), then this one is caught.

 From the code perspective, it sounds not right since 
register_page_bootmem_info_section() may miss some pfns when 
CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, just like the problem 
happened in page_ext_init().

Thanks,
Yang


>

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  reply	other threads:[~2016-05-25 23:44 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-25 21:00 [PATCH] mm: use early_pfn_to_nid in register_page_bootmem_info_node Yang Shi
2016-05-25 21:00 ` Yang Shi
2016-05-25 22:23 ` Andrew Morton
2016-05-25 22:23   ` Andrew Morton
2016-05-25 22:36   ` Shi, Yang [this message]
2016-05-25 22:36     ` Shi, Yang
2016-05-26  0:37     ` Joonsoo Kim
2016-05-26  0:37       ` Joonsoo Kim

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