x86: fix trim mtrr not to setup_memory two times

we could call find_max_pfn() directly instead of setup_memory() to get
max_pfn needed for mtrr trimming.

otherwise setup_memory() is called two times... that is duplicated...

[ mingo@elte.hu: both Thomas and me simulated a double call to
  setup_bootmem_allocator() and can confirm that it is a real bug
  which can hang in certain configs. It's not been reported yet but
  that is probably due to the relatively scarce nature of
  MTRR-trimming systems. ]

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

2 files changed, 4 insertions, 6 deletions

diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index a1d7071a51c9..2b3e5d45176b 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -406,8 +406,6 @@ static unsigned long __init setup_memory(void)
          */
         min_low_pfn = PFN_UP(init_pg_tables_end);
 
-        find_max_pfn();
-
         max_low_pfn = find_max_low_pfn();
 
 #ifdef CONFIG_HIGHMEM
@@ -764,12 +762,13 @@ void __init setup_arch(char **cmdline_p)
         if (efi_enabled)
                 efi_init();
 
-        max_low_pfn = setup_memory();
-
         /* update e820 for memory not covered by WB MTRRs */
+        find_max_pfn();
         mtrr_bp_init();
         if (mtrr_trim_uncached_memory(max_pfn))
-                max_low_pfn = setup_memory();
+                find_max_pfn();
+
+        max_low_pfn = setup_memory();
 
 #ifdef CONFIG_VMI
         /*
diff --git a/arch/x86/mm/discontig_32.c b/arch/x86/mm/discontig_32.c
index c394ca0720b8..8e25e06ff730 100644
--- a/arch/x86/mm/discontig_32.c
+++ b/arch/x86/mm/discontig_32.c
@@ -324,7 +324,6 @@ unsigned long __init setup_memory(void)
          * this space and use it to adjust the boundary between ZONE_NORMAL
          * and ZONE_HIGHMEM.
          */
-        find_max_pfn();
         get_memcfg_numa();
 
         kva_pages = calculate_numa_remap_pages();