On 04/08/17 11:12, Michal Hocko wrote:
> On Fri 04-08-17 11:02:46, Igor Stoppa wrote:
[...]
>> struct page {
>> /* First double word block */
>> unsigned long flags; /* Atomic flags, some possibly
>> * updated asynchronously */
>> union {
>> struct address_space *mapping; /* If low bit clear, points to
>> * inode address_space, or NULL.
>> * If page mapped as anonymous
>> * memory, low bit is set, and
>> * it points to anon_vma object:
>> * see PAGE_MAPPING_ANON below.
>> */
>> ...
>> }
>>
>> mapping seems to be used exclusively in 2 ways, based on the value of
>> its lower bit.
>
> Not really. The above applies to LRU pages. Please note that Slab pages
> use s_mem and huge pages use compound_mapcount. If vmalloc pages are
> using none of those already you can add a new field there.
Yes, both from reading the code and some experimentation, it seems that
vmalloc is not using either field.
I'll add a vm_area field as you advised.
Is this something I could send as standalone patch?
--
thank you, igor
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