1 files changed, 39 insertions, 8 deletions

diff --git a/kernel/pid.c b/kernel/pid.c
index fd996c1ed9f8..3e2cf8100acc 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -36,6 +36,7 @@
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
 #include <linux/syscalls.h>
+#include <linux/proc_fs.h>
 
 #define pid_hashfn(nr, ns)      \
         hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
@@ -78,6 +79,8 @@ struct pid_namespace init_pid_ns = {
         .last_pid = 0,
         .level = 0,
         .child_reaper = &init_task,
+        .user_ns = &init_user_ns,
+        .proc_inum = PROC_PID_INIT_INO,
 };
 EXPORT_SYMBOL_GPL(init_pid_ns);
 
@@ -269,8 +272,24 @@ void free_pid(struct pid *pid)
         unsigned long flags;
 
         spin_lock_irqsave(&pidmap_lock, flags);
-        for (i = 0; i <= pid->level; i++)
-                hlist_del_rcu(&pid->numbers[i].pid_chain);
+        for (i = 0; i <= pid->level; i++) {
+                struct upid *upid = pid->numbers + i;
+                struct pid_namespace *ns = upid->ns;
+                hlist_del_rcu(&upid->pid_chain);
+                switch(--ns->nr_hashed) {
+                case 1:
+                        /* When all that is left in the pid namespace
+                         * is the reaper wake up the reaper.  The reaper
+                         * may be sleeping in zap_pid_ns_processes().
+                         */
+                        wake_up_process(ns->child_reaper);
+                        break;
+                case 0:
+                        ns->nr_hashed = -1;
+                        schedule_work(&ns->proc_work);
+                        break;
+                }
+        }
         spin_unlock_irqrestore(&pidmap_lock, flags);
 
         for (i = 0; i <= pid->level; i++)
@@ -292,6 +311,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
                 goto out;
 
         tmp = ns;
+        pid->level = ns->level;
         for (i = ns->level; i >= 0; i--) {
                 nr = alloc_pidmap(tmp);
                 if (nr < 0)
@@ -302,22 +322,32 @@ struct pid *alloc_pid(struct pid_namespace *ns)
                 tmp = tmp->parent;
         }
 
+        if (unlikely(is_child_reaper(pid))) {
+                if (pid_ns_prepare_proc(ns))
+                        goto out_free;
+        }
+
         get_pid_ns(ns);
-        pid->level = ns->level;
         atomic_set(&pid->count, 1);
         for (type = 0; type < PIDTYPE_MAX; ++type)
                 INIT_HLIST_HEAD(&pid->tasks[type]);
 
         upid = pid->numbers + ns->level;
         spin_lock_irq(&pidmap_lock);
-        for ( ; upid >= pid->numbers; --upid)
+        if (ns->nr_hashed < 0)
+                goto out_unlock;
+        for ( ; upid >= pid->numbers; --upid) {
                 hlist_add_head_rcu(&upid->pid_chain,
                                 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
+                upid->ns->nr_hashed++;
+        }
         spin_unlock_irq(&pidmap_lock);
 
 out:
         return pid;
 
+out_unlock:
+        spin_unlock(&pidmap_lock);
 out_free:
         while (++i <= ns->level)
                 free_pidmap(pid->numbers + i);
@@ -344,7 +374,7 @@ EXPORT_SYMBOL_GPL(find_pid_ns);
 
 struct pid *find_vpid(int nr)
 {
-        return find_pid_ns(nr, current->nsproxy->pid_ns);
+        return find_pid_ns(nr, task_active_pid_ns(current));
 }
 EXPORT_SYMBOL_GPL(find_vpid);
 
@@ -428,7 +458,7 @@ struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
 
 struct task_struct *find_task_by_vpid(pid_t vnr)
 {
-        return find_task_by_pid_ns(vnr, current->nsproxy->pid_ns);
+        return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
 }
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
@@ -483,7 +513,7 @@ EXPORT_SYMBOL_GPL(pid_nr_ns);
 
 pid_t pid_vnr(struct pid *pid)
 {
-        return pid_nr_ns(pid, current->nsproxy->pid_ns);
+        return pid_nr_ns(pid, task_active_pid_ns(current));
 }
 EXPORT_SYMBOL_GPL(pid_vnr);
 
@@ -494,7 +524,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
 
         rcu_read_lock();
         if (!ns)
-                ns = current->nsproxy->pid_ns;
+                ns = task_active_pid_ns(current);
         if (likely(pid_alive(task))) {
                 if (type != PIDTYPE_PID)
                         task = task->group_leader;
@@ -569,6 +599,7 @@ void __init pidmap_init(void)
         /* Reserve PID 0. We never call free_pidmap(0) */
         set_bit(0, init_pid_ns.pidmap[0].page);
         atomic_dec(&init_pid_ns.pidmap[0].nr_free);
+        init_pid_ns.nr_hashed = 1;
 
         init_pid_ns.pid_cachep = KMEM_CACHE(pid,
                         SLAB_HWCACHE_ALIGN | SLAB_PANIC);