8 files changed, 40 insertions, 19 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 60433e2254a4..12d8cd461b41 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -38,6 +38,7 @@
 #include <linux/binfmts.h>
 #include <linux/swap.h>
 #include <linux/utsname.h>
+#include <linux/pid_namespace.h>
 #include <linux/module.h>
 #include <linux/namei.h>
 #include <linux/proc_fs.h>
@@ -620,8 +621,8 @@ static int de_thread(struct task_struct *tsk)
          * Reparenting needs write_lock on tasklist_lock,
          * so it is safe to do it under read_lock.
          */
-        if (unlikely(tsk->group_leader == child_reaper))
-                child_reaper = tsk;
+        if (unlikely(tsk->group_leader == child_reaper(tsk)))
+                tsk->nsproxy->pid_ns->child_reaper = tsk;
 
         zap_other_threads(tsk);
         read_unlock(&tasklist_lock);
diff --git a/include/linux/pid.h b/include/linux/pid.h
index 2c0007d17218..4dec047b1837 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -35,8 +35,9 @@ enum pid_type
  *
  * Holding a reference to struct pid solves both of these problems.
  * It is small so holding a reference does not consume a lot of
- * resources, and since a new struct pid is allocated when the numeric
- * pid value is reused we don't mistakenly refer to new processes.
+ * resources, and since a new struct pid is allocated when the numeric pid
+ * value is reused (when pids wrap around) we don't mistakenly refer to new
+ * processes.
  */
 
 struct pid
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 76e7c6b2cf33..d2a9d419f01f 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -19,6 +19,7 @@ struct pid_namespace {
         struct kref kref;
         struct pidmap pidmap[PIDMAP_ENTRIES];
         int last_pid;
+        struct task_struct *child_reaper;
 };
 
 extern struct pid_namespace init_pid_ns;
@@ -36,4 +37,9 @@ static inline void put_pid_ns(struct pid_namespace *ns)
         kref_put(&ns->kref, free_pid_ns);
 }
 
+static inline struct task_struct *child_reaper(struct task_struct *tsk)
+{
+        return tsk->nsproxy->pid_ns->child_reaper;
+}
+
 #endif /* _LINUX_PID_NS_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6fec1d419714..f0317edea141 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1400,7 +1400,6 @@ extern NORET_TYPE void do_group_exit(int);
 extern void daemonize(const char *, ...);
 extern int allow_signal(int);
 extern int disallow_signal(int);
-extern struct task_struct *child_reaper;
 
 extern int do_execve(char *, char __user * __user *, char __user * __user *, struct pt_regs *);
 extern long do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);
diff --git a/init/main.c b/init/main.c
index 4cdcd06e6d78..036f97c0c34c 100644
--- a/init/main.c
+++ b/init/main.c
@@ -51,6 +51,7 @@
 #include <linux/debug_locks.h>
 #include <linux/lockdep.h>
 #include <linux/utsrelease.h>
+#include <linux/pid_namespace.h>
 #include <linux/compile.h>
 
 #include <asm/io.h>
@@ -626,8 +627,6 @@ static int __init initcall_debug_setup(char *str)
 }
 __setup("initcall_debug", initcall_debug_setup);
 
-struct task_struct *child_reaper = &init_task;
-
 extern initcall_t __initcall_start[], __initcall_end[];
 
 static void __init do_initcalls(void)
@@ -727,7 +726,7 @@ static int init(void * unused)
          * assumptions about where in the task array this
          * can be found.
          */
-        child_reaper = current;
+        init_pid_ns.child_reaper = current;
 
         cad_pid = task_pid(current);
 
diff --git a/kernel/exit.c b/kernel/exit.c
index 28d9feedfd27..fd0e067952ab 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -22,6 +22,7 @@
 #include <linux/file.h>
 #include <linux/binfmts.h>
 #include <linux/nsproxy.h>
+#include <linux/pid_namespace.h>
 #include <linux/ptrace.h>
 #include <linux/profile.h>
 #include <linux/mount.h>
@@ -48,7 +49,6 @@
 #include <asm/mmu_context.h>
 
 extern void sem_exit (void);
-extern struct task_struct *child_reaper;
 
 static void exit_mm(struct task_struct * tsk);
 
@@ -260,7 +260,8 @@ static int has_stopped_jobs(int pgrp)
 }
 
 /**
- * reparent_to_init - Reparent the calling kernel thread to the init task.
+ * reparent_to_init - Reparent the calling kernel thread to the init task
+ * of the pid space that the thread belongs to.
  *
  * If a kernel thread is launched as a result of a system call, or if
  * it ever exits, it should generally reparent itself to init so that
@@ -278,8 +279,8 @@ static void reparent_to_init(void)
         ptrace_unlink(current);
         /* Reparent to init */
         remove_parent(current);
-        current->parent = child_reaper;
-        current->real_parent = child_reaper;
+        current->parent = child_reaper(current);
+        current->real_parent = child_reaper(current);
         add_parent(current);
 
         /* Set the exit signal to SIGCHLD so we signal init on exit */
@@ -662,7 +663,8 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
  * When we die, we re-parent all our children.
  * Try to give them to another thread in our thread
  * group, and if no such member exists, give it to
- * the global child reaper process (ie "init")
+ * the child reaper process (ie "init") in our pid
+ * space.
  */
 static void
 forget_original_parent(struct task_struct *father, struct list_head *to_release)
@@ -673,7 +675,7 @@ forget_original_parent(struct task_struct *father, struct list_head *to_release)
         do {
                 reaper = next_thread(reaper);
                 if (reaper == father) {
-                        reaper = child_reaper;
+                        reaper = child_reaper(father);
                         break;
                 }
         } while (reaper->exit_state);
@@ -859,8 +861,13 @@ fastcall NORET_TYPE void do_exit(long code)
                 panic("Aiee, killing interrupt handler!");
         if (unlikely(!tsk->pid))
                 panic("Attempted to kill the idle task!");
-        if (unlikely(tsk == child_reaper))
-                panic("Attempted to kill init!");
+        if (unlikely(tsk == child_reaper(tsk))) {
+                if (tsk->nsproxy->pid_ns != &init_pid_ns)
+                        tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
+                else
+                        panic("Attempted to kill init!");
+        }
+
 
         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
                 current->ptrace_message = code;
diff --git a/kernel/pid.c b/kernel/pid.c
index 1d9cc268b499..2efe9d8d367b 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -65,7 +65,8 @@ struct pid_namespace init_pid_ns = {
         .pidmap = {
                 [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
         },
-        .last_pid = 0
+        .last_pid = 0,
+        .child_reaper = &init_task
 };
 
 /*
diff --git a/kernel/signal.c b/kernel/signal.c
index 9eac4db60eda..1921ffdc5e77 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -24,6 +24,9 @@
 #include <linux/signal.h>
 #include <linux/capability.h>
 #include <linux/freezer.h>
+#include <linux/pid_namespace.h>
+#include <linux/nsproxy.h>
+
 #include <asm/param.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -1877,8 +1880,12 @@ relock:
                 if (sig_kernel_ignore(signr)) /* Default is nothing. */
                         continue;
 
-                /* Init gets no signals it doesn't want.  */
-                if (current == child_reaper)
+                /*
+                 * Init of a pid space gets no signals it doesn't want from
+                 * within that pid space. It can of course get signals from
+                 * its parent pid space.
+                 */
+                if (current == child_reaper(current))
                         continue;
 
                 if (sig_kernel_stop(signr)) {