Re: [PATCH 04/31] mm, vmscan: begin reclaiming pages on a per-node basis

[Mel Gorman]

On Mon, Jul 04, 2016 at 06:08:27PM +0800, Hillf Danton wrote:
> > @@ -2561,17 +2580,23 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
> >  	 * highmem pages could be pinning lowmem pages storing buffer_heads
> >  	 */
> >  	orig_mask = sc->gfp_mask;
> > -	if (buffer_heads_over_limit)
> > +	if (buffer_heads_over_limit) {
> >  		sc->gfp_mask |= __GFP_HIGHMEM;
> > +		sc->reclaim_idx = classzone_idx = gfp_zone(sc->gfp_mask);
> > +	}
> > 
> We need to push/pop ->reclaim_idx as ->gfp_mask handled?
> 

I saw no harm in having one full reclaim attempt reclaiming from all
zones if buffer_heads_over_limit was triggered. If it fails, the page
allocator will loop again and reset the reclaim_idx.

-- 
Mel Gorman
SUSE Labs