#ifdef CONFIG_PER_VMA_LOCK
long vm_lock_seq;
-
- /*
- * With default kernel config, lock's offset inside vm_area_struct is
- * at 56, which causes its two hot fields 'count' and 'owner' to be in
- * 2 different cachelines. When the lock is contended, both of the
- * 2 fields will be accessed frequently and current layout will help
- * to reduce cache bouncing.
- *
- * So please be careful with adding new fields before lock, which can
- * push the 2 fields into one cacheline.
- */
struct rw_semaphore *lock;
#endif
/*