1 files changed, 23 insertions, 7 deletions

diff --git a/fs/exec.c b/fs/exec.c
index c7397c46ad6d..950ebd43cdc3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -616,6 +616,15 @@ static int de_thread(struct task_struct *tsk)
                 kmem_cache_free(sighand_cachep, newsighand);
                 return -EAGAIN;
         }
+
+        /*
+         * child_reaper ignores SIGKILL, change it now.
+         * Reparenting needs write_lock on tasklist_lock,
+         * so it is safe to do it under read_lock.
+         */
+        if (unlikely(current->group_leader == child_reaper))
+                child_reaper = current;
+
         zap_other_threads(current);
         read_unlock(&tasklist_lock);
 
@@ -699,22 +708,30 @@ static int de_thread(struct task_struct *tsk)
                 remove_parent(current);
                 remove_parent(leader);
 
-                switch_exec_pids(leader, current);
+
+                /* Become a process group leader with the old leader's pid.
+                 * Note: The old leader also uses thispid until release_task
+                 *       is called.  Odd but simple and correct.
+                 */
+                detach_pid(current, PIDTYPE_PID);
+                current->pid = leader->pid;
+                attach_pid(current, PIDTYPE_PID,  current->pid);
+                attach_pid(current, PIDTYPE_PGID, current->signal->pgrp);
+                attach_pid(current, PIDTYPE_SID,  current->signal->session);
+                list_add_tail(&current->tasks, &init_task.tasks);
 
                 current->parent = current->real_parent = leader->real_parent;
                 leader->parent = leader->real_parent = child_reaper;
                 current->group_leader = current;
                 leader->group_leader = leader;
 
-                add_parent(current, current->parent);
-                add_parent(leader, leader->parent);
+                add_parent(current);
+                add_parent(leader);
                 if (ptrace) {
                         current->ptrace = ptrace;
                         __ptrace_link(current, parent);
                 }
 
-                list_del(&current->tasks);
-                list_add_tail(&current->tasks, &init_task.tasks);
                 current->exit_signal = SIGCHLD;
 
                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
@@ -751,7 +768,6 @@ no_thread_group:
                 /*
                  * Move our state over to newsighand and switch it in.
                  */
-                spin_lock_init(&newsighand->siglock);
                 atomic_set(&newsighand->count, 1);
                 memcpy(newsighand->action, oldsighand->action,
                        sizeof(newsighand->action));
@@ -768,7 +784,7 @@ no_thread_group:
                 write_unlock_irq(&tasklist_lock);
 
                 if (atomic_dec_and_test(&oldsighand->count))
-                        sighand_free(oldsighand);
+                        kmem_cache_free(sighand_cachep, oldsighand);
         }
 
         BUG_ON(!thread_group_leader(current));