linux-master/mm/swapfile.c

105 /* Activity counter to indicate that a swapon or swapoff has occurred */
1241  * prevent swapoff, such as the folio in swap cache is locked, RCU
1243  * because of swapoff.  Then, we need to enclose all swap related
1248  * prevent swapoff, because synchronize_rcu() is called in swapoff()
1253  * via preventing the swap device from being swapoff, until
1256  * Notice that swapoff or swapoff+swapon can still happen before the
1259  * to prevent swapoff.  The caller must be prepared for that.  For
1264  *     ...				swapoff+swapon
1273  * swap device which has been swapoff.  And in do_swap_page(), after
1276  * has been swapoff or swapoff+swapon.
2402 	 * swap_active_head needs to be priority ordered for swapoff(),
2462 SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
2553 	 * operations from racing with swapoff.
3388  * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3495 		 * __swap_duplicate(): the swap device may be swapoff
3662  * free_swap_count_continuations - swapoff free all the continuation pages