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

From: Vlastimil Babka
Date: Thu Nov 05 2015 - 03:17:39 EST


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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