1 files changed, 11 insertions, 2 deletions

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) {