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

Roman Gushchin
2020-03-27T14:42:16Z

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@fb.com>

Acked-by: Roman Gushchin <guro@fb.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