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Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to alloc_huge_page_nodemask

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to alloc_huge_page_nodemask
Date 2017-06-12 14:30 +0200
Message-ID <tRwDM-22k-15@gated-at.bofh.it> (permalink)
References <tQ0mB-1kN-3@gated-at.bofh.it> <tQ0mD-1kN-41@gated-at.bofh.it> <tQ190-1Rp-3@gated-at.bofh.it> <tRtwe-ch-9@gated-at.bofh.it> <tRwaK-1Dv-23@gated-at.bofh.it>
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On Mon 12-06-17 13:53:51, Vlastimil Babka wrote:
> On 06/12/2017 11:06 AM, Michal Hocko wrote:
[...]
> > -/* Movability of hugepages depends on migration support. */
> > -static inline gfp_t htlb_alloc_mask(struct hstate *h)
> > +static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
> >  {
> > -	if (hugepages_treat_as_movable || hugepage_migration_supported(h))
> > -		return GFP_HIGHUSER_MOVABLE;
> > -	else
> > -		return GFP_HIGHUSER;
> > +	if (nid != NUMA_NO_NODE)
> > +		return dequeue_huge_page_node_exact(h, nid);
> > +
> > +	return dequeue_huge_page_nodemask(h, nid, NULL);
> 
> This with nid == NUMA_NO_NODE will break at node_zonelist(nid,
> gfp_mask); in dequeue_huge_page_nodemask(). I guess just use the local
> node as preferred.

You are right. Anyway I have a patch to remove this helper altogether.

> > -retry_cpuset:
> > -	cpuset_mems_cookie = read_mems_allowed_begin();
> > -	gfp_mask = htlb_alloc_mask(h);
> > -	nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> > -	zonelist = node_zonelist(nid, gfp_mask);
> > -
> > -	for_each_zone_zonelist_nodemask(zone, z, zonelist,
> > -						MAX_NR_ZONES - 1, nodemask) {
> > -		if (cpuset_zone_allowed(zone, gfp_mask)) {
> > -			page = dequeue_huge_page_node(h, zone_to_nid(zone));
> > -			if (page) {
> > -				if (avoid_reserve)
> > -					break;
> > -				if (!vma_has_reserves(vma, chg))
> > -					break;
> > -
> > -				SetPagePrivate(page);
> > -				h->resv_huge_pages--;
> > -				break;
> > -			}
> > -		}
> > +	nid = huge_node(vma, address, htlb_alloc_mask(h), &mpol, &nodemask);
> > +	page = dequeue_huge_page_nodemask(h, nid, nodemask);
> > +	if (page && !(avoid_reserve || (!vma_has_reserves(vma, chg)))) {
> 
> Ugh that's hard to parse.
> What about: if (page && !avoid_reserve && vma_has_reserves(...)) ?

Yeah, I have just translated the two breaks into a single condition
without scratching my head to much. If you think that this face of De Morgan
is nicer I can use it.
-- 
Michal Hocko
SUSE Labs

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Thread

[RFC PATCH 4/4] hugetlb: add support for preferred node to alloc_huge_page_nodemask Michal Hocko <mhocko@kernel.org> - 2017-06-08 09:50 +0200
  Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Vlastimil Babka <vbabka@suse.cz> - 2017-06-08 10:40 +0200
    Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Michal Hocko <mhocko@kernel.org> - 2017-06-12 11:10 +0200
      Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Michal Hocko <mhocko@kernel.org> - 2017-06-12 13:50 +0200
      Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Vlastimil Babka <vbabka@suse.cz> - 2017-06-12 14:00 +0200
        Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Michal Hocko <mhocko@kernel.org> - 2017-06-12 14:30 +0200
  Re: [RFC PATCH 4/4] hugetlb: add support for preferred node to  alloc_huge_page_nodemask Michal Hocko <mhocko@kernel.org> - 2017-06-12 17:30 +0200

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