linux-kernel - Re: [PATCH 2/2] mm: hugetlb: Use node interface of cma

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Date:   Fri, 27 Mar 2020 07:41:55 -0700
From:   Roman Gushchin <guro@...com>
To:     Michal Hocko <mhocko@...nel.org>
CC:     Aslan Bakirov <aslan@...com>, <akpm@...ux-foundation.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <kernel-team@...com>, <riel@...riel.com>, <hannes@...xchg.org>
Subject: Re: [PATCH 2/2] mm: hugetlb: Use node interface of cma

On Fri, Mar 27, 2020 at 09:06:10AM +0100, Michal Hocko wrote:
> On Thu 26-03-20 14:27:18, Aslan Bakirov wrote:
> > With introduction of numa node interface for CMA, this patch is for using that
> > interface for allocating memory on numa nodes if NUMA is configured.
> > This will be more efficient  and cleaner because first, instead of iterating
> > mem range of each numa node, cma_declare_contigueous_nid() will do
> > its own address finding if we pass 0 for  both min_pfn and max_pfn,
> > second, it can also handle caseswhere NUMA is not configured
> > by passing NUMA_NO_NODE as an argument.
> > 
> > In addition, checking if desired size of memory is available or not,
> > is happening in cma_declare_contiguous_nid()  because base and
> > limit will be determined there, since 0(any) for  base and
> > 0(any) for limit is passed as argument to the function.
> 
> This looks much better than the original patch. Can we simply squash
> your and Roman's patch in the mmotm tree and post it for the review in
> one piece? It would be slightly easier to review that way.

I'm glad you liked it! I agree, it's much nicer now, thanks to Aslan!

I think it's simpler to keep it as a separate patch, because there was
already a fix by Randy Dunlap on top of my original version.

> 
> > Signed-off-by: Aslan Bakirov <aslan@...com>

Acked-by: Roman Gushchin <guro@...com>

Thanks!

> 
> Thanks!
> 
> > ---
> >  mm/hugetlb.c | 40 +++++++++++-----------------------------
> >  1 file changed, 11 insertions(+), 29 deletions(-)
> > 
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index b9f0c903c4cf..62989220c4ff 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -5573,42 +5573,24 @@ void __init hugetlb_cma_reserve(int order)
> >  
> >  	reserved = 0;
> >  	for_each_node_state(nid, N_ONLINE) {
> > -		unsigned long min_pfn = 0, max_pfn = 0;
> >  		int res;
> > -#ifdef CONFIG_NUMA
> > -		unsigned long start_pfn, end_pfn;
> > -		int i;
> >  
> > -		for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
> > -			if (!min_pfn)
> > -				min_pfn = start_pfn;
> > -			max_pfn = end_pfn;
> > -		}
> > -#else
> > -		min_pfn = min_low_pfn;
> > -		max_pfn = max_low_pfn;
> > -#endif
> >  		size = min(per_node, hugetlb_cma_size - reserved);
> >  		size = round_up(size, PAGE_SIZE << order);
> > -
> > -		if (size > ((max_pfn - min_pfn) << PAGE_SHIFT) / 2) {
> > -			pr_warn("hugetlb_cma: cma_area is too big, please try less than %lu MiB\n",
> > -				round_down(((max_pfn - min_pfn) << PAGE_SHIFT) *
> > -					   nr_online_nodes / 2 / SZ_1M,
> > -					   PAGE_SIZE << order));
> > -			break;
> > -		}
> > -
> > -		res = cma_declare_contiguous(PFN_PHYS(min_pfn), size,
> > -					     PFN_PHYS(max_pfn),
> > +		
> > +		
> > +#ifndef CONFIG_NUMA
> > +		nid = NUMA_NO_NODE
> > +#endif		
> > +		res = cma_declare_contiguous_nid(0, size,
> > +					     0, 
> >  					     PAGE_SIZE << order,
> >  					     0, false,
> > -					     "hugetlb", &hugetlb_cma[nid]);
> > +					     "hugetlb", &hugetlb_cma[nid], nid);		
> > +
> >  		if (res) {
> > -			phys_addr_t begpa = PFN_PHYS(min_pfn);
> > -			phys_addr_t endpa = PFN_PHYS(max_pfn);
> > -			pr_warn("%s: reservation failed: err %d, node %d, [%pap, %pap)\n",
> > -				__func__, res, nid, &begpa, &endpa);
> > +			pr_warn("%s: reservation failed: err %d, node %d\n",
> > +				__func__, res, nid);
> >  			break;
> >  		}
> >  
> > -- 
> > 2.17.1
> 
> -- 
> Michal Hocko
> SUSE Labs