From grsecurity-2.1.14-2.6.31.6-200912051443.patch:

-#define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
+#define __access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
+#define access_ok(type, addr, size)                                    \
+({                                                                     \
+       long __size = size;                                             \
+       unsigned long __addr = (unsigned long)addr;                     \
+       unsigned long __addr_ao = __addr & PAGE_MASK;                   \
+       unsigned long __end_ao = __addr + __size - 1;                   \
+       bool __ret_ao = __range_not_ok(__addr, __size) == 0;            \
+       if (__ret_ao && unlikely((__end_ao ^ __addr_ao) & PAGE_MASK)) { \
+               for (; __addr_ao <= __end_ao; __addr_ao += PAGE_SIZE) { \
+                       char __c_ao;                                    \
+                       if (__size > PAGE_SIZE)                         \
+                               cond_resched();                         \
+                       if (__get_user(__c_ao, (char __user *)__addr_ao))\
+                               break;                                  \
+                       if (type != VERIFY_WRITE)                       \
+                               continue;                               \
+                       if (__put_user(__c_ao, (char __user *)__addr_ao))\
+                               break;                                  \
+               }                                                       \
+       }                                                               \
+       __ret_ao;                                                       \
+})