linux-kernel - Re: [PATCH v2] mm/slub: don't wait for high-order page allocation

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Message-ID: <20150811063655.GC18998@dhcp22.suse.cz>
Date:	Tue, 11 Aug 2015 08:36:55 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>, Shaohua Li <shli@...com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH v2] mm/slub: don't wait for high-order page allocation

On Mon 10-08-15 09:40:22, Joonsoo Kim wrote:
> On Fri, Aug 07, 2015 at 05:05:01PM +0200, Michal Hocko wrote:
> > On Fri 07-08-15 11:10:03, Joonsoo Kim wrote:
> > [...]
> > > diff --git a/mm/slub.c b/mm/slub.c
> > > index 257283f..52b9025 100644
> > > --- a/mm/slub.c
> > > +++ b/mm/slub.c
> > > @@ -1364,6 +1364,8 @@ 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_WAIT) && oo_order(oo) > oo_order(s->min))
> > > +		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_WAIT;
> > 
> > Wouldn't it be preferable to "fix" the __GFP_WAIT behavior than spilling
> > __GFP_NOMEMALLOC around the kernel? GFP flags are getting harder and
> > harder to use right and that is a signal we should thing about it and
> > unclutter the current state.
> 
> Maybe, it is preferable. Could you try that?

I will try to cook up something during the week.

> Anyway, it is separate issue so I don't want pending this patch until
> that change.

OK, fair enough, at least this one is in mm proper...
-- 
Michal Hocko
SUSE Labs
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