diff --git a/ipc/sem.c b/ipc/sem.c
index cddd5b5fde51..b3757ea0694b 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -92,7 +92,14 @@
 /* One semaphore structure for each semaphore in the system. */
 struct sem {
 	int	semval;		/* current value */
-	int	sempid;		/* pid of last operation */
+	/*
+	 * PID of the process that last modified the semaphore. For
+	 * Linux, specifically these are:
+	 *  - semop
+	 *  - semctl, via SETVAL and SETALL.
+	 *  - at task exit when performing undo adjustments (see exit_sem).
+	 */
+	int	sempid;
 	spinlock_t	lock;	/* spinlock for fine-grained semtimedop */
 	struct list_head pending_alter; /* pending single-sop operations */
 					/* that alter the semaphore */
@@ -1444,8 +1451,10 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 			goto out_unlock;
 		}
 
-		for (i = 0; i < nsems; i++)
+		for (i = 0; i < nsems; i++) {
 			sma->sem_base[i].semval = sem_io[i];
+			sma->sem_base[i].sempid = task_tgid_vnr(current);
+		}
 
 		ipc_assert_locked_object(&sma->sem_perm);
 		list_for_each_entry(un, &sma->list_id, list_id) {