Re: [PATCH V5 4/6] mm: reclaim MADV_FREE pages

[Johannes Weiner]

On Fri, Feb 24, 2017 at 01:31:47PM -0800, Shaohua Li wrote:
> When memory pressure is high, we free MADV_FREE pages. If the pages are
> not dirty in pte, the pages could be freed immediately. Otherwise we
> can't reclaim them. We put the pages back to anonumous LRU list (by
> setting SwapBacked flag) and the pages will be reclaimed in normal
> swapout way.
> 
> We use normal page reclaim policy. Since MADV_FREE pages are put into
> inactive file list, such pages and inactive file pages are reclaimed
> according to their age. This is expected, because we don't want to
> reclaim too many MADV_FREE pages before used once pages.
> 
> Based on Minchan's original patch
> 
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Shaohua Li <shli@xxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>

FWIW, I agree with Minchan that this could be folded into the previous
patch and would be a little neater. But I don't feel strongly in this
case since I didn't have any trouble reviewing the patches like this -
void mark_page_lazyfree(struct page *) is an easy API to remember.