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-rw-r--r--fs/exec.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 0291a68a3626..3234a0c32d54 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -678,6 +678,18 @@ static int de_thread(struct task_struct *tsk)
while (leader->exit_state != EXIT_ZOMBIE)
yield();
+ /*
+ * The only record we have of the real-time age of a
+ * process, regardless of execs it's done, is start_time.
+ * All the past CPU time is accumulated in signal_struct
+ * from sister threads now dead. But in this non-leader
+ * exec, nothing survives from the original leader thread,
+ * whose birth marks the true age of this process now.
+ * When we take on its identity by switching to its PID, we
+ * also take its birthdate (always earlier than our own).
+ */
+ current->start_time = leader->start_time;
+
spin_lock(&leader->proc_lock);
spin_lock(&current->proc_lock);
proc_dentry1 = proc_pid_unhash(current);
@@ -723,7 +735,12 @@ static int de_thread(struct task_struct *tsk)
current->parent = current->real_parent = leader->real_parent;
leader->parent = leader->real_parent = child_reaper;
current->group_leader = current;
- leader->group_leader = leader;
+ leader->group_leader = current;
+
+ /* Reduce leader to a thread */
+ detach_pid(leader, PIDTYPE_PGID);
+ detach_pid(leader, PIDTYPE_SID);
+ list_del_init(&leader->tasks);
add_parent(current);
add_parent(leader);