linux-kernel - Re: [PATCH 3/5] mm, page_owner: copy page owner info during migration

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Message-ID: <563B109D.6030001@suse.cz>
Date:	Thu, 5 Nov 2015 09:17:33 +0100
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Minchan Kim <minchan@...nel.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Mel Gorman <mgorman@...e.de>
Subject: Re: [PATCH 3/5] mm, page_owner: copy page owner info during migration

On 11/05/2015 09:10 AM, Joonsoo Kim wrote:
> On Wed, Nov 04, 2015 at 04:00:59PM +0100, Vlastimil Babka wrote:
>> +void __copy_page_owner(struct page *oldpage, struct page *newpage)
>> +{
>> +	struct page_ext *old_ext = lookup_page_ext(oldpage);
>> +	struct page_ext *new_ext = lookup_page_ext(newpage);
>> +	int i;
>> +
>> +	new_ext->order = old_ext->order;
>> +	new_ext->gfp_mask = old_ext->gfp_mask;
>> +	new_ext->nr_entries = old_ext->nr_entries;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++)
>> +		new_ext->trace_entries[i] = old_ext->trace_entries[i];
>> +
>> +	__set_bit(PAGE_EXT_OWNER, &new_ext->flags);
>> +}
>> +
> 
> Need to clear PAGE_EXT_OWNER bit in oldppage.

Hm, I thought that the freeing of the oldpage, which follows the migration,
would take care of that. And if it hit some bug and dump_page before being
freed, we would still have some info to print?

Thanks

> Thanks.
> 
>>  static ssize_t
>>  print_page_owner(char __user *buf, size_t count, unsigned long pfn,
>>  		struct page *page, struct page_ext *page_ext)
>> -- 
>> 2.6.2
>> 
>> --
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> 

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