Re: [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE

Mika Penttilä
2020-03-15T08:54:15Z

On 15.3.2020 10.18, Wei Yang wrote:
> On Fri, Feb 28, 2020 at 11:38:18AM +0800, Huang, Ying wrote:
>> From: Huang Ying <ying.huang@intel.com>
>>
>> Now !PageSwapBacked() is used as the flag for the pages freed lazily
>> via MADV_FREE. This isn't obvious enough. So Dave suggested to add a
>> new page flag for that to improve the code readability.
> I am confused with the usage of PageSwapBacked().
>
> Previously I thought this flag means the page is swapin, set in
> swapin_readahead(). While I found page_add_new_anon_rmap() would set it too.
> This means every anon page would carry this flag. Then what is this flag
> means?
>
>

But not all PageSwapBacked() pages are anon, like shmem.

--Mika