mm: save some bytes in mm_struct by filling holes on 64bit

Save some bytes in mm_struct by filling holes

Putting int values together for better packing on 64bit shrinks sizeof(struct
mm_struct) from 776 bytes to 764 bytes.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm_types.h

@@ -172,6 +172,7 @@ struct mm_struct {
 	atomic_t mm_users;			/* How many users with user space? */
 	atomic_t mm_count;			/* How many references to "struct mm_struct" (users count as 1) */
 	int map_count;				/* number of VMAs */
+	int core_waiters;
 	struct rw_semaphore mmap_sem;
 	spinlock_t page_table_lock;		/* Protects page tables and some counters */
 
@@ -216,11 +217,10 @@ struct mm_struct {
 	unsigned long flags; /* Must use atomic bitops to access the bits */
 
 	/* coredumping support */
-	int core_waiters;
 	struct completion *core_startup_done, core_done;
 
 	/* aio bits */
-	rwlock_t		ioctx_list_lock;
+	rwlock_t		ioctx_list_lock;	/* aio lock */
 	struct kioctx		*ioctx_list;
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 	struct mem_cgroup *mem_cgroup;