2 files changed, 34 insertions, 10 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 9b5f7d7049d0..44ccb028c350 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -777,7 +777,7 @@ void __init setup_bootmem_allocator(void)
         after_init_bootmem = 1;
 }
 
-static void __init find_early_table_space(unsigned long end)
+static void __init find_early_table_space(unsigned long end, int use_pse)
 {
         unsigned long puds, pmds, ptes, tables, start;
 
@@ -787,7 +787,7 @@ static void __init find_early_table_space(unsigned long end)
         pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
         tables += PAGE_ALIGN(pmds * sizeof(pmd_t));
 
-        if (cpu_has_pse) {
+        if (use_pse) {
                 unsigned long extra;
 
                 extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
@@ -827,12 +827,22 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         pgd_t *pgd_base = swapper_pg_dir;
         unsigned long start_pfn, end_pfn;
         unsigned long big_page_start;
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        /*
+         * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
+         * This will simplify cpa(), which otherwise needs to support splitting
+         * large pages into small in interrupt context, etc.
+         */
+        int use_pse = 0;
+#else
+        int use_pse = cpu_has_pse;
+#endif
 
         /*
          * Find space for the kernel direct mapping tables.
          */
         if (!after_init_bootmem)
-                find_early_table_space(end);
+                find_early_table_space(end, use_pse);
 
 #ifdef CONFIG_X86_PAE
         set_nx();
@@ -878,7 +888,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
         if (start_pfn < end_pfn)
                 kernel_physical_mapping_init(pgd_base, start_pfn, end_pfn,
-                                                cpu_has_pse);
+                                             use_pse);
 
         /* tail is not big page alignment ? */
         start_pfn = end_pfn;
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 1ba945eb6282..9d7587ac1ebc 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -456,13 +456,14 @@ phys_pud_update(pgd_t *pgd, unsigned long addr, unsigned long end,
         return phys_pud_init(pud, addr, end, page_size_mask);
 }
 
-static void __init find_early_table_space(unsigned long end)
+static void __init find_early_table_space(unsigned long end, int use_pse,
+                                          int use_gbpages)
 {
         unsigned long puds, pmds, ptes, tables, start;
 
         puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
         tables = round_up(puds * sizeof(pud_t), PAGE_SIZE);
-        if (direct_gbpages) {
+        if (use_gbpages) {
                 unsigned long extra;
                 extra = end - ((end>>PUD_SHIFT) << PUD_SHIFT);
                 pmds = (extra + PMD_SIZE - 1) >> PMD_SHIFT;
@@ -470,7 +471,7 @@ static void __init find_early_table_space(unsigned long end)
                 pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
         tables += round_up(pmds * sizeof(pmd_t), PAGE_SIZE);
 
-        if (cpu_has_pse) {
+        if (use_pse) {
                 unsigned long extra;
                 extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
                 ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -640,6 +641,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
 
         struct map_range mr[NR_RANGE_MR];
         int nr_range, i;
+        int use_pse, use_gbpages;
 
         printk(KERN_INFO "init_memory_mapping\n");
 
@@ -653,9 +655,21 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
         if (!after_bootmem)
                 init_gbpages();
 
-        if (direct_gbpages)
+#ifdef CONFIG_DEBUG_PAGEALLOC
+        /*
+         * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
+         * This will simplify cpa(), which otherwise needs to support splitting
+         * large pages into small in interrupt context, etc.
+         */
+        use_pse = use_gbpages = 0;
+#else
+        use_pse = cpu_has_pse;
+        use_gbpages = direct_gbpages;
+#endif
+
+        if (use_gbpages)
                 page_size_mask |= 1 << PG_LEVEL_1G;
-        if (cpu_has_pse)
+        if (use_pse)
                 page_size_mask |= 1 << PG_LEVEL_2M;
 
         memset(mr, 0, sizeof(mr));
@@ -716,7 +730,7 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
                          (mr[i].page_size_mask & (1<<PG_LEVEL_2M))?"2M":"4k"));
 
         if (!after_bootmem)
-                find_early_table_space(end);
+                find_early_table_space(end, use_pse, use_gbpages);
 
         for (i = 0; i < nr_range; i++)
                 last_map_addr = kernel_physical_mapping_init(