v4.19.13 snapshot.
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 0000000..8301293
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Virtual Memory Map support
+ *
+ * (C) 2007 sgi. Christoph Lameter.
+ *
+ * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
+ * virt_to_page, page_address() to be implemented as a base offset
+ * calculation without memory access.
+ *
+ * However, virtual mappings need a page table and TLBs. Many Linux
+ * architectures already map their physical space using 1-1 mappings
+ * via TLBs. For those arches the virtual memory map is essentially
+ * for free if we use the same page size as the 1-1 mappings. In that
+ * case the overhead consists of a few additional pages that are
+ * allocated to create a view of memory for vmemmap.
+ *
+ * The architecture is expected to provide a vmemmap_populate() function
+ * to instantiate the mapping.
+ */
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/memremap.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+/*
+ * Allocate a block of memory to be used to back the virtual memory map
+ * or to back the page tables that are used to create the mapping.
+ * Uses the main allocators if they are available, else bootmem.
+ */
+
+static void * __ref __earlyonly_bootmem_alloc(int node,
+ unsigned long size,
+ unsigned long align,
+ unsigned long goal)
+{
+ return memblock_virt_alloc_try_nid_raw(size, align, goal,
+ BOOTMEM_ALLOC_ACCESSIBLE, node);
+}
+
+void * __meminit vmemmap_alloc_block(unsigned long size, int node)
+{
+ /* If the main allocator is up use that, fallback to bootmem. */
+ if (slab_is_available()) {
+ gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
+ int order = get_order(size);
+ static bool warned;
+ struct page *page;
+
+ page = alloc_pages_node(node, gfp_mask, order);
+ if (page)
+ return page_address(page);
+
+ if (!warned) {
+ warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
+ "vmemmap alloc failure: order:%u", order);
+ warned = true;
+ }
+ return NULL;
+ } else
+ return __earlyonly_bootmem_alloc(node, size, size,
+ __pa(MAX_DMA_ADDRESS));
+}
+
+/* need to make sure size is all the same during early stage */
+void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
+{
+ void *ptr = sparse_buffer_alloc(size);
+
+ if (!ptr)
+ ptr = vmemmap_alloc_block(size, node);
+ return ptr;
+}
+
+static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
+{
+ return altmap->base_pfn + altmap->reserve + altmap->alloc
+ + altmap->align;
+}
+
+static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
+{
+ unsigned long allocated = altmap->alloc + altmap->align;
+
+ if (altmap->free > allocated)
+ return altmap->free - allocated;
+ return 0;
+}
+
+/**
+ * altmap_alloc_block_buf - allocate pages from the device page map
+ * @altmap: device page map
+ * @size: size (in bytes) of the allocation
+ *
+ * Allocations are aligned to the size of the request.
+ */
+void * __meminit altmap_alloc_block_buf(unsigned long size,
+ struct vmem_altmap *altmap)
+{
+ unsigned long pfn, nr_pfns, nr_align;
+
+ if (size & ~PAGE_MASK) {
+ pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
+ __func__, size);
+ return NULL;
+ }
+
+ pfn = vmem_altmap_next_pfn(altmap);
+ nr_pfns = size >> PAGE_SHIFT;
+ nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
+ nr_align = ALIGN(pfn, nr_align) - pfn;
+ if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
+ return NULL;
+
+ altmap->alloc += nr_pfns;
+ altmap->align += nr_align;
+ pfn += nr_align;
+
+ pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
+ __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
+ return __va(__pfn_to_phys(pfn));
+}
+
+void __meminit vmemmap_verify(pte_t *pte, int node,
+ unsigned long start, unsigned long end)
+{
+ unsigned long pfn = pte_pfn(*pte);
+ int actual_node = early_pfn_to_nid(pfn);
+
+ if (node_distance(actual_node, node) > LOCAL_DISTANCE)
+ pr_warn("[%lx-%lx] potential offnode page_structs\n",
+ start, end - 1);
+}
+
+pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
+{
+ pte_t *pte = pte_offset_kernel(pmd, addr);
+ if (pte_none(*pte)) {
+ pte_t entry;
+ void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
+ if (!p)
+ return NULL;
+ entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
+ set_pte_at(&init_mm, addr, pte, entry);
+ }
+ return pte;
+}
+
+static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
+{
+ void *p = vmemmap_alloc_block(size, node);
+
+ if (!p)
+ return NULL;
+ memset(p, 0, size);
+
+ return p;
+}
+
+pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
+{
+ pmd_t *pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd)) {
+ void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+ if (!p)
+ return NULL;
+ pmd_populate_kernel(&init_mm, pmd, p);
+ }
+ return pmd;
+}
+
+pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
+{
+ pud_t *pud = pud_offset(p4d, addr);
+ if (pud_none(*pud)) {
+ void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+ if (!p)
+ return NULL;
+ pud_populate(&init_mm, pud, p);
+ }
+ return pud;
+}
+
+p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
+{
+ p4d_t *p4d = p4d_offset(pgd, addr);
+ if (p4d_none(*p4d)) {
+ void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+ if (!p)
+ return NULL;
+ p4d_populate(&init_mm, p4d, p);
+ }
+ return p4d;
+}
+
+pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
+{
+ pgd_t *pgd = pgd_offset_k(addr);
+ if (pgd_none(*pgd)) {
+ void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+ if (!p)
+ return NULL;
+ pgd_populate(&init_mm, pgd, p);
+ }
+ return pgd;
+}
+
+int __meminit vmemmap_populate_basepages(unsigned long start,
+ unsigned long end, int node)
+{
+ unsigned long addr = start;
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ for (; addr < end; addr += PAGE_SIZE) {
+ pgd = vmemmap_pgd_populate(addr, node);
+ if (!pgd)
+ return -ENOMEM;
+ p4d = vmemmap_p4d_populate(pgd, addr, node);
+ if (!p4d)
+ return -ENOMEM;
+ pud = vmemmap_pud_populate(p4d, addr, node);
+ if (!pud)
+ return -ENOMEM;
+ pmd = vmemmap_pmd_populate(pud, addr, node);
+ if (!pmd)
+ return -ENOMEM;
+ pte = vmemmap_pte_populate(pmd, addr, node);
+ if (!pte)
+ return -ENOMEM;
+ vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
+ }
+
+ return 0;
+}
+
+struct page * __meminit sparse_mem_map_populate(unsigned long pnum, 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);
+
+ if (vmemmap_populate(start, end, nid, altmap))
+ return NULL;
+
+ return map;
+}