Re: [PATCH v5 4/9] mm/migrate: clear __GFP_RECLAIM to make the migration callback consistent with regular THP allocations

[Joonsoo Kim]

On Mon, Jul 13, 2020 at 09:52:20AM +0200, Vlastimil Babka wrote:
> On 7/13/20 8:41 AM, js1304@xxxxxxxxx wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> > 
> > new_page_nodemask is a migration callback and it tries to use a common
> > gfp flags for the target page allocation whether it is a base page or a
> > THP. The later only adds GFP_TRANSHUGE to the given mask. This results
> > in the allocation being slightly more aggressive than necessary because
> > the resulting gfp mask will contain also __GFP_RECLAIM_KSWAPD. THP
> > allocations usually exclude this flag to reduce over eager background
> > reclaim during a high THP allocation load which has been seen during
> > large mmaps initialization. There is no indication that this is a
> > problem for migration as well but theoretically the same might happen
> > when migrating large mappings to a different node. Make the migration
> > callback consistent with regular THP allocations.
> > 
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> 
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> 
> Thanks!
> 
> Typo below (I assume Andrew will fix it)
> 
> > ---
> >  mm/migrate.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index 3b3d918..1cfc965 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -1547,6 +1547,11 @@ struct page *new_page_nodemask(struct page *page,
> >  	}
> >  
> >  	if (PageTransHuge(page)) {
> > +		/*
> > +		 * clear __GFP_RECALIM to make the migration callback
> 
>                          __GFP_RECLAIM
> 

Okay. Here goes a fixed version.

Thanks!


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