Re: [PATCH 2/2] mm: vmpressure: fix sending wrong events on underflow

From: Minchan Kim
Date: Mon Jan 30 2017 - 19:00:09 EST

On Fri, Jan 27, 2017 at 01:43:37PM +0530, Vinayak Menon wrote:
> At the end of a window period, if the reclaimed pages
> is greater than scanned, an unsigned underflow can
> result in a huge pressure value and thus a critical event.
> Reclaimed pages is found to go higher than scanned because
> of the addition of reclaimed slab pages to reclaimed in
> shrink_node without a corresponding increment to scanned
> pages. Minchan Kim mentioned that this can also happen in
> the case of a THP page where the scanned is 1 and reclaimed
> could be 512.
> Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>

Thanks for the fix up!