5 files changed, 211 insertions, 4 deletions

diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index 30d8d33491dd..52226e14bd7d 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -46,6 +46,12 @@
          __pgdat->node_start_pfn;                                       \
 })
 
+#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
+
+/* memmap is virtually contigious.  */
+#define __pfn_to_page(pfn)      (vmemmap + (pfn))
+#define __page_to_pfn(page)     ((page) - vmemmap)
+
 #elif defined(CONFIG_SPARSEMEM)
 /*
  * Note: section's mem_map is encorded to reflect its start_pfn.
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1692dd6cb915..d216abbd0574 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1218,5 +1218,11 @@ extern int randomize_va_space;
 
 const char * arch_vma_name(struct vm_area_struct *vma);
 
+struct page *sparse_early_mem_map_populate(unsigned long pnum, int nid);
+int vmemmap_populate(struct page *start_page, unsigned long pages, int node);
+int vmemmap_populate_pmd(pud_t *, unsigned long, unsigned long, int);
+void *vmemmap_alloc_block(unsigned long size, int node);
+void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
diff --git a/mm/Makefile b/mm/Makefile
index 245e33ab00c4..d28f63e05b46 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
 obj-$(CONFIG_HUGETLBFS) += hugetlb.o
 obj-$(CONFIG_NUMA)      += mempolicy.o
 obj-$(CONFIG_SPARSEMEM) += sparse.o
+obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
 obj-$(CONFIG_SHMEM) += shmem.o
 obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o
 obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 000000000000..7bb7a4b96d74
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,181 @@
+/*
+ * Virtual Memory Map support
+ *
+ * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>.
+ *
+ * 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 memmory 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.
+ *
+ * Special Kconfig settings:
+ *
+ * CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP
+ *
+ *      The architecture has its own functions to populate the memory
+ *      map and provides a vmemmap_populate function.
+ *
+ * CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD
+ *
+ *      The architecture provides functions to populate the pmd level
+ *      of the vmemmap mappings.  Allowing mappings using large pages
+ *      where available.
+ *
+ *      If neither are set then PAGE_SIZE mappings are generated which
+ *      require one PTE/TLB per PAGE_SIZE chunk of the virtual memory map.
+ */
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.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.
+ */
+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()) {
+                struct page *page = alloc_pages_node(node,
+                                GFP_KERNEL | __GFP_ZERO, get_order(size));
+                if (page)
+                        return page_address(page);
+                return NULL;
+        } else
+                return __alloc_bootmem_node(NODE_DATA(node), size, size,
+                                __pa(MAX_DMA_ADDRESS));
+}
+
+#ifndef CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP
+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 (actual_node != node)
+                printk(KERN_WARNING "[%lx-%lx] potential offnode "
+                        "page_structs\n", start, end - 1);
+}
+
+#ifndef CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD
+static int __meminit vmemmap_populate_pte(pmd_t *pmd, unsigned long addr,
+                                        unsigned long end, int node)
+{
+        pte_t *pte;
+
+        for (pte = pte_offset_kernel(pmd, addr); addr < end;
+                                                pte++, addr += PAGE_SIZE)
+                if (pte_none(*pte)) {
+                        pte_t entry;
+                        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                        if (!p)
+                                return -ENOMEM;
+
+                        entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
+                        set_pte(pte, entry);
+
+                } else
+                        vmemmap_verify(pte, node, addr + PAGE_SIZE, end);
+
+        return 0;
+}
+
+int __meminit vmemmap_populate_pmd(pud_t *pud, unsigned long addr,
+                                                unsigned long end, int node)
+{
+        pmd_t *pmd;
+        int error = 0;
+        unsigned long next;
+
+        for (pmd = pmd_offset(pud, addr); addr < end && !error;
+                                                pmd++, addr = next) {
+                if (pmd_none(*pmd)) {
+                        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                        if (!p)
+                                return -ENOMEM;
+
+                        pmd_populate_kernel(&init_mm, pmd, p);
+                } else
+                        vmemmap_verify((pte_t *)pmd, node,
+                                        pmd_addr_end(addr, end), end);
+                next = pmd_addr_end(addr, end);
+                error = vmemmap_populate_pte(pmd, addr, next, node);
+        }
+        return error;
+}
+#endif /* CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD */
+
+static int __meminit vmemmap_populate_pud(pgd_t *pgd, unsigned long addr,
+                                                unsigned long end, int node)
+{
+        pud_t *pud;
+        int error = 0;
+        unsigned long next;
+
+        for (pud = pud_offset(pgd, addr); addr < end && !error;
+                                                pud++, addr = next) {
+                if (pud_none(*pud)) {
+                        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                        if (!p)
+                                return -ENOMEM;
+
+                        pud_populate(&init_mm, pud, p);
+                }
+                next = pud_addr_end(addr, end);
+                error = vmemmap_populate_pmd(pud, addr, next, node);
+        }
+        return error;
+}
+
+int __meminit vmemmap_populate(struct page *start_page,
+                                                unsigned long nr, int node)
+{
+        pgd_t *pgd;
+        unsigned long addr = (unsigned long)start_page;
+        unsigned long end = (unsigned long)(start_page + nr);
+        unsigned long next;
+        int error = 0;
+
+        printk(KERN_DEBUG "[%lx-%lx] Virtual memory section"
+                " (%ld pages) node %d\n", addr, end - 1, nr, node);
+
+        for (pgd = pgd_offset_k(addr); addr < end && !error;
+                                        pgd++, addr = next) {
+                if (pgd_none(*pgd)) {
+                        void *p = vmemmap_alloc_block(PAGE_SIZE, node);
+                        if (!p)
+                                return -ENOMEM;
+
+                        pgd_populate(&init_mm, pgd, p);
+                }
+                next = pgd_addr_end(addr,end);
+                error = vmemmap_populate_pud(pgd, addr, next, node);
+        }
+        return error;
+}
+#endif /* !CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP */
+
+struct page __init *sparse_early_mem_map_populate(unsigned long pnum, int nid)
+{
+        struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION);
+        int error = vmemmap_populate(map, PAGES_PER_SECTION, nid);
+        if (error)
+                return NULL;
+
+        return map;
+}
diff --git a/mm/sparse.c b/mm/sparse.c
index 54f3940406cb..52843a76feed 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -9,6 +9,8 @@
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
 
 /*
  * Permanent SPARSEMEM data:
@@ -222,11 +224,10 @@ void *alloc_bootmem_high_node(pg_data_t *pgdat, unsigned long size)
         return NULL;
 }
 
-static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+struct page __init *sparse_early_mem_map_populate(unsigned long pnum, int nid)
 {
         struct page *map;
-        struct mem_section *ms = __nr_to_section(pnum);
-        int nid = sparse_early_nid(ms);
 
         map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
         if (map)
@@ -239,10 +240,22 @@ static struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
 
         map = alloc_bootmem_node(NODE_DATA(nid),
                         sizeof(struct page) * PAGES_PER_SECTION);
+        return map;
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+struct page __init *sparse_early_mem_map_alloc(unsigned long pnum)
+{
+        struct page *map;
+        struct mem_section *ms = __nr_to_section(pnum);
+        int nid = sparse_early_nid(ms);
+
+        map = sparse_early_mem_map_populate(pnum, nid);
         if (map)
                 return map;
 
-        printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
+        printk(KERN_ERR "%s: sparsemem memory map backing failed "
+                        "some memory will not be available.\n", __FUNCTION__);
         ms->section_mem_map = 0;
         return NULL;
 }