mm/sparsemem: convert kmalloc_section_memmap() to populate_section_memmap()

Allow sub-section sized ranges to be added to the memmap.

populate_section_memmap() takes an explict pfn range rather than
assuming a full section, and those parameters are plumbed all the way
through to vmmemap_populate().  There should be no sub-section usage in
current deployments.  New warnings are added to clarify which memmap
allocation paths are sub-section capable.

Link: http://lkml.kernel.org/r/156092352058.979959.6551283472062305149.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 7fec05796796..200aef686722 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -245,19 +245,26 @@ int __meminit vmemmap_populate_basepages(unsigned long start,
         return 0;
 }
 
-struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid,
-                struct vmem_altmap *altmap)
+struct page * __meminit __populate_section_memmap(unsigned long pfn,
+                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
 {
         unsigned long start;
         unsigned long end;
-        struct page *map;
 
-        map = pfn_to_page(pnum * PAGES_PER_SECTION);
-        start = (unsigned long)map;
-        end = (unsigned long)(map + PAGES_PER_SECTION);
+        /*
+         * The minimum granularity of memmap extensions is
+         * PAGES_PER_SUBSECTION as allocations are tracked in the
+         * 'subsection_map' bitmap of the section.
+         */
+        end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION);
+        pfn &= PAGE_SUBSECTION_MASK;
+        nr_pages = end - pfn;
+
+        start = (unsigned long) pfn_to_page(pfn);
+        end = start + nr_pages * sizeof(struct page);
 
         if (vmemmap_populate(start, end, nid, altmap))
                 return NULL;
 
-        return map;
+        return pfn_to_page(pfn);
 }