fix ->shm_file leak

index cd4d87a..485dc0e 100644
@@ -306,17 +306,18 @@ void fput(struct file *file)
 {
 	if (atomic_long_dec_and_test(&file->f_count)) {
 		struct task_struct *task = current;
+		unsigned long flags;
+
 		file_sb_list_del(file);
-		if (unlikely(in_interrupt() || task->flags & PF_KTHREAD)) {
-			unsigned long flags;
-			spin_lock_irqsave(&delayed_fput_lock, flags);
-			list_add(&file->f_u.fu_list, &delayed_fput_list);
-			schedule_work(&delayed_fput_work);
-			spin_unlock_irqrestore(&delayed_fput_lock, flags);
-			return;
+		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
+			init_task_work(&file->f_u.fu_rcuhead, ____fput);
+			if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
+				return;
 		}
-		init_task_work(&file->f_u.fu_rcuhead, ____fput);
-		task_work_add(task, &file->f_u.fu_rcuhead, true);
+		spin_lock_irqsave(&delayed_fput_lock, flags);
+		list_add(&file->f_u.fu_list, &delayed_fput_list);
+		schedule_work(&delayed_fput_work);
+		spin_unlock_irqrestore(&delayed_fput_lock, flags);
 	}
 }
 

index 3a2bbc5..94b1bfa 100644
@@ -265,18 +265,15 @@ static void __fput(struct file *file)
 	mntput(mnt);
 }
 
-static DEFINE_SPINLOCK(delayed_fput_lock);
-static LIST_HEAD(delayed_fput_list);
+static LLIST_HEAD(delayed_fput_list);
 static void delayed_fput(struct work_struct *unused)
 {
-	LIST_HEAD(head);
-	spin_lock_irq(&delayed_fput_lock);
-	list_splice_init(&delayed_fput_list, &head);
-	spin_unlock_irq(&delayed_fput_lock);
-	while (!list_empty(&head)) {
-		struct file *f = list_first_entry(&head, struct file, f_u.fu_list);
-		list_del_init(&f->f_u.fu_list);
-		__fput(f);
+	struct llist_node *node = llist_del_all(&delayed_fput_list);
+	struct llist_node *next;
+
+	for (; node; node = next) {
+		next = llist_next(node);
+		__fput(llist_entry(node, struct file, f_u.fu_llist));
 	}
 }
 

@@ -306,7 +303,6 @@ void fput(struct file *file)
 {
 	if (atomic_long_dec_and_test(&file->f_count)) {
 		struct task_struct *task = current;
-		unsigned long flags;
 
 		file_sb_list_del(file);
 		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {

@@ -320,10 +316,9 @@ void fput(struct file *file)
 			 * fput to avoid leaking *file.
 			 */
 		}
-		spin_lock_irqsave(&delayed_fput_lock, flags);
-		list_add(&file->f_u.fu_list, &delayed_fput_list);
-		schedule_work(&delayed_fput_work);
-		spin_unlock_irqrestore(&delayed_fput_lock, flags);
+
+		if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
+			schedule_work(&delayed_fput_work);
 	}
 }
 

index 43db02e..8a60d99 100644
@@ -10,6 +10,7 @@
 #include <linux/stat.h>
 #include <linux/cache.h>
 #include <linux/list.h>
+#include <linux/llist.h>
 #include <linux/radix-tree.h>
 #include <linux/rbtree.h>
 #include <linux/init.h>

@@ -767,6 +768,7 @@ struct file {
 	 */
 	union {
 		struct list_head	fu_list;
+		struct llist_node	fu_llist;
 		struct rcu_head 	fu_rcuhead;
 	} f_u;
 	struct path		f_path;

index a5199f6..3e2b969 100644
@@ -151,18 +151,13 @@ static inline struct llist_node *llist_next(struct llist_node *node)
  */
 static inline bool llist_add(struct llist_node *new, struct llist_head *head)
 {
-	struct llist_node *entry, *old_entry;
-
-	entry = head->first;
-	for (;;) {
-		old_entry = entry;
-		new->next = entry;
-		entry = cmpxchg(&head->first, old_entry, new);
-		if (entry == old_entry)
-			break;
-	}
-
-	return old_entry == NULL;
+	struct llist_node *first;
+
+	do {
+		new->next = first = ACCESS_ONCE(head->first);
+	} while (cmpxchg(&head->first, first, new) != first);
+
+	return !first;
 }
 
 /**

index 4a15115..4a70d12 100644
@@ -39,18 +39,13 @@
 bool llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
 		     struct llist_head *head)
 {
-	struct llist_node *entry, *old_entry;
+	struct llist_node *first;
 
-	entry = head->first;
-	for (;;) {
-		old_entry = entry;
-		new_last->next = entry;
-		entry = cmpxchg(&head->first, old_entry, new_first);
-		if (entry == old_entry)
-			break;
-	}
+	do {
+		new_last->next = first = ACCESS_ONCE(head->first);
+	} while (cmpxchg(&head->first, first, new_first) != first);
 
-	return old_entry == NULL;
+	return !first;
 }
 EXPORT_SYMBOL_GPL(llist_add_batch);
 

index 3e2b969..cdaa7f0 100644
@@ -142,6 +142,9 @@ static inline struct llist_node *llist_next(struct llist_node *node)
 	return node->next;
 }
 
+extern bool llist_add_batch(struct llist_node *new_first,
+			    struct llist_node *new_last,
+			    struct llist_head *head);
 /**
  * llist_add - add a new entry
  * @new:	new entry to be added

@@ -151,13 +154,7 @@ static inline struct llist_node *llist_next(struct llist_node *node)
  */
 static inline bool llist_add(struct llist_node *new, struct llist_head *head)
 {
-	struct llist_node *first;
-
-	do {
-		new->next = first = ACCESS_ONCE(head->first);
-	} while (cmpxchg(&head->first, first, new) != first);
-
-	return !first;
+	return llist_add_batch(new, new, head);
 }
 
 /**

@@ -173,9 +170,6 @@ static inline struct llist_node *llist_del_all(struct llist_head *head)
 	return xchg(&head->first, NULL);
 }
 
-extern bool llist_add_batch(struct llist_node *new_first,
-			    struct llist_node *new_last,
-			    struct llist_head *head);
 extern struct llist_node *llist_del_first(struct llist_head *head);
 
 #endif /* LLIST_H */

index 8fc3c8f..c623cd3 100644
@@ -644,7 +644,6 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 	 *	jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 	 */
 	forget_original_parent(tsk);
-	exit_task_namespaces(tsk);
 
 	write_lock_irq(&tasklist_lock);
 	if (group_dead)

@@ -790,6 +789,7 @@ void do_exit(long code)
 	exit_shm(tsk);
 	exit_files(tsk);
 	exit_fs(tsk);
+	exit_task_namespaces(tsk);
 	exit_task_work(tsk);
 	check_stack_usage();
 	exit_thread();