x86, numa, 32-bit: make sure get we kva space

when 1/3 user/kernel split is used, and less memory is installed, or if
we have a big hole below 4g, max_low_pfn is still using 3g-128m

try to go down from max_low_pfn until we get it. otherwise will panic.

need to make 32-bit code to use register_e820_active_regions ... later.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 5 deletions

diff --git a/arch/x86/mm/discontig_32.c b/arch/x86/mm/discontig_32.c
index 914a81ee7855..7ced26ab9aec 100644
--- a/arch/x86/mm/discontig_32.c
+++ b/arch/x86/mm/discontig_32.c
@@ -328,6 +328,7 @@ unsigned long __init setup_memory(void)
 {
         int nid;
         unsigned long system_start_pfn, system_max_low_pfn;
+        long kva_target_pfn;
 
         /*
          * When mapping a NUMA machine we allocate the node_mem_map arrays
@@ -344,11 +345,17 @@ unsigned long __init setup_memory(void)
         system_start_pfn = min_low_pfn = PFN_UP(init_pg_tables_end);
 
         system_max_low_pfn = max_low_pfn = find_max_low_pfn();
-        kva_start_pfn = round_down(max_low_pfn - kva_pages, PTRS_PER_PTE);
-        kva_start_pfn = find_e820_area(kva_start_pfn<<PAGE_SHIFT,
-                                max_low_pfn<<PAGE_SHIFT,
-                                kva_pages<<PAGE_SHIFT,
-                                PTRS_PER_PTE<<PAGE_SHIFT) >> PAGE_SHIFT;
+        kva_target_pfn = round_down(max_low_pfn - kva_pages, PTRS_PER_PTE);
+        do {
+                kva_start_pfn = find_e820_area(kva_target_pfn<<PAGE_SHIFT,
+                                        max_low_pfn<<PAGE_SHIFT,
+                                        kva_pages<<PAGE_SHIFT,
+                                        PTRS_PER_PTE<<PAGE_SHIFT) >> PAGE_SHIFT;
+                kva_target_pfn -= PTRS_PER_PTE;
+        } while (kva_start_pfn == -1UL && kva_target_pfn > min_low_pfn);
+
+        if (kva_start_pfn == -1UL)
+                panic("Can not get kva space\n");
 
         printk("kva_start_pfn ~ %ld find_max_low_pfn() ~ %ld\n",
                 kva_start_pfn, max_low_pfn);