x86-64, NUMA: Don't call __pa() with invalid address in numa_reset_distance()

Do not call __pa(numa_distance) if it was not allocated before.
Calling with invalid address triggers VIRTUAL_BUG_ON() in
__phys_addr() if CONFIG_DEBUG_VIRTUAL.

Also reported by Ingo.

 http://thread.gmane.org/gmane.linux.kernel/1101306/focus=1101785

- v2: Change to check existing path as tj requested.
- tj: Description update.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 8ce617735900..1bd6de4aa714 100644
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -371,11 +371,13 @@ static void __init numa_reset_distance(void)
 {
         size_t size;
 
-        size = numa_distance_cnt * sizeof(numa_distance[0]);
-        memblock_x86_free_range(__pa(numa_distance),
-                                __pa(numa_distance) + size);
+        if (numa_distance_cnt) {
+                size = numa_distance_cnt * sizeof(numa_distance[0]);
+                memblock_x86_free_range(__pa(numa_distance),
+                                        __pa(numa_distance) + size);
+                numa_distance_cnt = 0;
+        }
         numa_distance = NULL;
-        numa_distance_cnt = 0;
 }
 
 /*