Re: [RFC PATCH 1/2] mm, vmscan: account the number of isolated pages per zone

From: Michal Hocko
Date: Wed Jan 25 2017 - 04:53:48 EST

On Fri 20-01-17 22:27:27, Tetsuo Handa wrote:
> Mel Gorman wrote:
> > On Thu, Jan 19, 2017 at 12:23:36PM +0100, Michal Hocko wrote:
> > > So what do you think about the following? Tetsuo, would you be willing
> > > to run this patch through your torture testing please?
> >
> > I'm fine with treating this as a starting point.
> OK. So I tried to test this patch but I failed at preparation step.
> There are too many pending mm patches and I'm not sure which patch on
> which linux-next snapshot I should try.

The current linux-next should be good to test. It contains all patches
sitting in the mmotm tree. If you want a more stable base then you can
use mmotm git tree
(git:// #since-4.9
or its #auto-latest alias)

> Also as another question,
> too_many_isolated() loop exists in both mm/vmscan.c and mm/compaction.c
> but why this patch does not touch the loop in mm/compaction.c part?

I am not yet convinced the compaction suffers from the same problem.
Compaction backs off much sooner so that path shouldn't get into
pathological situation AFAICS. I might be wrong here but I think we
should start with the reclaim path first.
Michal Hocko