mm: fix atomic_t overflow in vm

The atomic_t type is 32bit but a 64bit system can have more than 2^32
pages of virtual address space available.  Without this we overflow on
ludicrously large mappings

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 74a323d..32dc14c 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -139,7 +139,7 @@
 #define K(x) ((x) << (PAGE_SHIFT - 10))
 	si_meminfo(&i);
 	si_swapinfo(&i);
-	committed = atomic_read(&vm_committed_space);
+	committed = atomic_long_read(&vm_committed_space);
 	allowed = ((totalram_pages - hugetlb_total_pages())
 		* sysctl_overcommit_ratio / 100) + total_swap_pages;