1 files changed, 21 insertions, 5 deletions

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index d3c72ad8d09e..410c3365ad8f 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -1372,18 +1372,32 @@ check_deadlock(struct task_struct *curr, struct held_lock *next,
                struct lockdep_map *next_instance, int read)
 {
         struct held_lock *prev;
+        struct held_lock *nest = NULL;
         int i;
 
         for (i = 0; i < curr->lockdep_depth; i++) {
                 prev = curr->held_locks + i;
+
+                if (prev->instance == next->nest_lock)
+                        nest = prev;
+
                 if (hlock_class(prev) != hlock_class(next))
                         continue;
+
                 /*
                  * Allow read-after-read recursion of the same
                  * lock class (i.e. read_lock(lock)+read_lock(lock)):
                  */
                 if ((read == 2) && prev->read)
                         return 2;
+
+                /*
+                 * We're holding the nest_lock, which serializes this lock's
+                 * nesting behaviour.
+                 */
+                if (nest)
+                        return 2;
+
                 return print_deadlock_bug(curr, prev, next);
         }
         return 1;
@@ -2507,7 +2521,7 @@ EXPORT_SYMBOL_GPL(lockdep_init_map);
  */
 static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
                           int trylock, int read, int check, int hardirqs_off,
-                          unsigned long ip)
+                          struct lockdep_map *nest_lock, unsigned long ip)
 {
         struct task_struct *curr = current;
         struct lock_class *class = NULL;
@@ -2566,6 +2580,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
         hlock->class_idx = class - lock_classes + 1;
         hlock->acquire_ip = ip;
         hlock->instance = lock;
+        hlock->nest_lock = nest_lock;
         hlock->trylock = trylock;
         hlock->read = read;
         hlock->check = check;
@@ -2717,7 +2732,7 @@ found_it:
                 if (!__lock_acquire(hlock->instance,
                         hlock_class(hlock)->subclass, hlock->trylock,
                                 hlock->read, hlock->check, hlock->hardirqs_off,
-                                hlock->acquire_ip))
+                                hlock->nest_lock, hlock->acquire_ip))
                         return 0;
         }
 
@@ -2778,7 +2793,7 @@ found_it:
                 if (!__lock_acquire(hlock->instance,
                         hlock_class(hlock)->subclass, hlock->trylock,
                                 hlock->read, hlock->check, hlock->hardirqs_off,
-                                hlock->acquire_ip))
+                                hlock->nest_lock, hlock->acquire_ip))
                         return 0;
         }
 
@@ -2915,7 +2930,8 @@ EXPORT_SYMBOL_GPL(lock_set_subclass);
  * and also avoid lockdep recursion:
  */
 void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
-                          int trylock, int read, int check, unsigned long ip)
+                          int trylock, int read, int check,
+                          struct lockdep_map *nest_lock, unsigned long ip)
 {
         unsigned long flags;
 
@@ -2930,7 +2946,7 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 
         current->lockdep_recursion = 1;
         __lock_acquire(lock, subclass, trylock, read, check,
-                       irqs_disabled_flags(flags), ip);
+                       irqs_disabled_flags(flags), nest_lock, ip);
         current->lockdep_recursion = 0;
         raw_local_irq_restore(flags);
 }