linux-kernel - Re: [PATCH 1/2] mm/slub: wake up kswapd for initial high order allocation

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Date:   Wed, 6 Sep 2017 19:21:10 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Christopher Lameter <cl@...ux.com>
Cc:     js1304@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Mel Gorman <mgorman@...hsingularity.net>,
        Vlastimil Babka <vbabka@...e.cz>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 1/2] mm/slub: wake up kswapd for initial high order
 allocation

On Wed 06-09-17 10:59:09, Cristopher Lameter wrote:
> On Wed, 6 Sep 2017, js1304@...il.com wrote:
> 
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -1578,8 +1578,12 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
> >  	 * so we fall-back to the minimum order allocation.
> >  	 */
> >  	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
> > -	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
> > -		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
> > +	if (oo_order(oo) > oo_order(s->min)) {
> > +		if (alloc_gfp & __GFP_DIRECT_RECLAIM) {
> > +			alloc_gfp |= __GFP_NOMEMALLOC;
> > +			alloc_gfp &= ~__GFP_DIRECT_RECLAIM;
> > +		}
> > +	}
> >
> 
> Can we come up with another inline function in gfp.h for this as well?

What do you mean? The oo_order thing?

> Well and needing these functions to manipulate flags actually indicates
> that we may need a cleanup of the GFP flags at some point. There is a buch
> of flags that disable things and some that enable things.

Good luck with that
-- 
Michal Hocko
SUSE Labs