[IA64] fix show_mem for VIRTUAL_MEM_MAP+FLATMEM

contig.c (FLATMEM) requires the same optimization as in discontig.c for show_mem
when VIRTUAL_MEM_MAP is in use. Otherwise FLATMEM has softlockup timeouts.
This was boot tested for memory configuration: SPARSEMEM,
DISCONTIG+VIRTUAL_MEM_MAP, FLATMEM, FLATMEM+VIRTUAL_MEM_MAP and
FLATMEM+VIRTUAL_MEM_MAP with largest memory gap less than LARGE_GAP by
using boot parameter "mem=".

This was boot tested and "echo m >/proc/sysrq-trigger" output evaluated for
: FLATMEM, FLATMEM+VIRTUAL_MEM_MAP, DISCONTIGMEM+VIRTUAL_MEM_MAP and
SPARSEMEM.

Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 2f50c064513c..30617ccb4f7e 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -415,6 +415,61 @@ ia64_mmu_init (void *my_cpu_data)
 }
 
 #ifdef CONFIG_VIRTUAL_MEM_MAP
+int vmemmap_find_next_valid_pfn(int node, int i)
+{
+        unsigned long end_address, hole_next_pfn;
+        unsigned long stop_address;
+        pg_data_t *pgdat = NODE_DATA(node);
+
+        end_address = (unsigned long) &vmem_map[pgdat->node_start_pfn + i];
+        end_address = PAGE_ALIGN(end_address);
+
+        stop_address = (unsigned long) &vmem_map[
+                pgdat->node_start_pfn + pgdat->node_spanned_pages];
+
+        do {
+                pgd_t *pgd;
+                pud_t *pud;
+                pmd_t *pmd;
+                pte_t *pte;
+
+                pgd = pgd_offset_k(end_address);
+                if (pgd_none(*pgd)) {
+                        end_address += PGDIR_SIZE;
+                        continue;
+                }
+
+                pud = pud_offset(pgd, end_address);
+                if (pud_none(*pud)) {
+                        end_address += PUD_SIZE;
+                        continue;
+                }
+
+                pmd = pmd_offset(pud, end_address);
+                if (pmd_none(*pmd)) {
+                        end_address += PMD_SIZE;
+                        continue;
+                }
+
+                pte = pte_offset_kernel(pmd, end_address);
+retry_pte:
+                if (pte_none(*pte)) {
+                        end_address += PAGE_SIZE;
+                        pte++;
+                        if ((end_address < stop_address) &&
+                            (end_address != ALIGN(end_address, 1UL << PMD_SHIFT)))
+                                goto retry_pte;
+                        continue;
+                }
+                /* Found next valid vmem_map page */
+                break;
+        } while (end_address < stop_address);
+
+        end_address = min(end_address, stop_address);
+        end_address = end_address - (unsigned long) vmem_map + sizeof(struct page) - 1;
+        hole_next_pfn = end_address / sizeof(struct page);
+        return hole_next_pfn - pgdat->node_start_pfn;
+}
 
 int __init
 create_mem_map_page_table (u64 start, u64 end, void *arg)