Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Continued user-access cleanups in the futex code.

   - percpu-rwsem rewrite that uses its own waitqueue and atomic_t
     instead of an embedded rwsem. This addresses a couple of
     weaknesses, but the primary motivation was complications on the -rt
     kernel.

   - Introduce raw lock nesting detection on lockdep
     (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
     lock differences. This too originates from -rt.

   - Reuse lockdep zapped chain_hlocks entries, to conserve RAM
     footprint on distro-ish kernels running into the "BUG:
     MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
     chain-entries pool.

   - Misc cleanups, smaller fixes and enhancements - see the changelog
     for details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  Documentation/locking/locktypes: Minor copy editor fixes
  Documentation/locking/locktypes: Further clarifications and wordsmithing
  m68knommu: Remove mm.h include from uaccess_no.h
  x86: get rid of user_atomic_cmpxchg_inatomic()
  generic arch_futex_atomic_op_inuser() doesn't need access_ok()
  x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
  x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
  objtool: whitelist __sanitizer_cov_trace_switch()
  [parisc, s390, sparc64] no need for access_ok() in futex handling
  sh: no need of access_ok() in arch_futex_atomic_op_inuser()
  futex: arch_futex_atomic_op_inuser() calling conventions change
  completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
  lockdep: Add posixtimer context tracing bits
  lockdep: Annotate irq_work
  lockdep: Add hrtimer context tracing bits
  lockdep: Introduce wait-type checks
  completion: Use simple wait queues
  sched/swait: Prepare usage in completions
  ...

25 files changed, 837 insertions, 361 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 9c706af713fb..221bf6a9e98a 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -331,12 +331,12 @@ void lockdep_assert_cpus_held(void)
 
 static void lockdep_acquire_cpus_lock(void)
 {
-	rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
+	rwsem_acquire(&cpu_hotplug_lock.dep_map, 0, 0, _THIS_IP_);
 }
 
 static void lockdep_release_cpus_lock(void)
 {
-	rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, _THIS_IP_);
+	rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_);
 }
 
 /*
diff --git a/kernel/exit.c b/kernel/exit.c
index 0b81b26a872a..764960fabfa1 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w)
 		wake_up_process(task);
 	rcu_read_unlock();
 }
+EXPORT_SYMBOL_GPL(rcuwait_wake_up);
 
 /*
  * Determine if a process group is "orphaned", according to the POSIX
diff --git a/kernel/futex.c b/kernel/futex.c
index 82dfacb3250e..b59532862bc0 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -135,8 +135,7 @@
  *
  * Where (A) orders the waiters increment and the futex value read through
  * atomic operations (see hb_waiters_inc) and where (B) orders the write
- * to futex and the waiters read -- this is done by the barriers for both
- * shared and private futexes in get_futex_key_refs().
+ * to futex and the waiters read (see hb_waiters_pending()).
  *
  * This yields the following case (where X:=waiters, Y:=futex):
  *
@@ -331,17 +330,6 @@ static void compat_exit_robust_list(struct task_struct *curr);
 static inline void compat_exit_robust_list(struct task_struct *curr) { }
 #endif
 
-static inline void futex_get_mm(union futex_key *key)
-{
-	mmgrab(key->private.mm);
-	/*
-	 * Ensure futex_get_mm() implies a full barrier such that
-	 * get_futex_key() implies a full barrier. This is relied upon
-	 * as smp_mb(); (B), see the ordering comment above.
-	 */
-	smp_mb__after_atomic();
-}
-
 /*
  * Reflects a new waiter being added to the waitqueue.
  */
@@ -370,6 +358,10 @@ static inline void hb_waiters_dec(struct futex_hash_bucket *hb)
 static inline int hb_waiters_pending(struct futex_hash_bucket *hb)
 {
 #ifdef CONFIG_SMP
+	/*
+	 * Full barrier (B), see the ordering comment above.
+	 */
+	smp_mb();
 	return atomic_read(&hb->waiters);
 #else
 	return 1;
@@ -407,69 +399,6 @@ static inline int match_futex(union futex_key *key1, union futex_key *key2)
 		&& key1->both.offset == key2->both.offset);
 }
 
-/*
- * Take a reference to the resource addressed by a key.
- * Can be called while holding spinlocks.
- *
- */
-static void get_futex_key_refs(union futex_key *key)
-{
-	if (!key->both.ptr)
-		return;
-
-	/*
-	 * On MMU less systems futexes are always "private" as there is no per
-	 * process address space. We need the smp wmb nevertheless - yes,
-	 * arch/blackfin has MMU less SMP ...
-	 */
-	if (!IS_ENABLED(CONFIG_MMU)) {
-		smp_mb(); /* explicit smp_mb(); (B) */
-		return;
-	}
-
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-	case FUT_OFF_INODE:
-		smp_mb();		/* explicit smp_mb(); (B) */
-		break;
-	case FUT_OFF_MMSHARED:
-		futex_get_mm(key); /* implies smp_mb(); (B) */
-		break;
-	default:
-		/*
-		 * Private futexes do not hold reference on an inode or
-		 * mm, therefore the only purpose of calling get_futex_key_refs
-		 * is because we need the barrier for the lockless waiter check.
-		 */
-		smp_mb(); /* explicit smp_mb(); (B) */
-	}
-}
-
-/*
- * Drop a reference to the resource addressed by a key.
- * The hash bucket spinlock must not be held. This is
- * a no-op for private futexes, see comment in the get
- * counterpart.
- */
-static void drop_futex_key_refs(union futex_key *key)
-{
-	if (!key->both.ptr) {
-		/* If we're here then we tried to put a key we failed to get */
-		WARN_ON_ONCE(1);
-		return;
-	}
-
-	if (!IS_ENABLED(CONFIG_MMU))
-		return;
-
-	switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
-	case FUT_OFF_INODE:
-		break;
-	case FUT_OFF_MMSHARED:
-		mmdrop(key->private.mm);
-		break;
-	}
-}
-
 enum futex_access {
 	FUTEX_READ,
 	FUTEX_WRITE
@@ -601,7 +530,6 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, enum futex_a
 	if (!fshared) {
 		key->private.mm = mm;
 		key->private.address = address;
-		get_futex_key_refs(key);  /* implies smp_mb(); (B) */
 		return 0;
 	}
 
@@ -741,8 +669,6 @@ again:
 		rcu_read_unlock();
 	}
 
-	get_futex_key_refs(key); /* implies smp_mb(); (B) */
-
 out:
 	put_page(page);
 	return err;
@@ -750,7 +676,6 @@ out:
 
 static inline void put_futex_key(union futex_key *key)
 {
-	drop_futex_key_refs(key);
 }
 
 /**
@@ -1740,10 +1665,9 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
 		oparg = 1 << oparg;
 	}
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
-
+	pagefault_disable();
 	ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
+	pagefault_enable();
 	if (ret)
 		return ret;
 
@@ -1885,7 +1809,6 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
 		plist_add(&q->list, &hb2->chain);
 		q->lock_ptr = &hb2->lock;
 	}
-	get_futex_key_refs(key2);
 	q->key = *key2;
 }
 
@@ -1907,7 +1830,6 @@ static inline
 void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 			   struct futex_hash_bucket *hb)
 {
-	get_futex_key_refs(key);
 	q->key = *key;
 
 	__unqueue_futex(q);
@@ -2018,7 +1940,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 			 u32 *cmpval, int requeue_pi)
 {
 	union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
-	int drop_count = 0, task_count = 0, ret;
+	int task_count = 0, ret;
 	struct futex_pi_state *pi_state = NULL;
 	struct futex_hash_bucket *hb1, *hb2;
 	struct futex_q *this, *next;
@@ -2139,7 +2061,6 @@ retry_private:
 		 */
 		if (ret > 0) {
 			WARN_ON(pi_state);
-			drop_count++;
 			task_count++;
 			/*
 			 * If we acquired the lock, then the user space value
@@ -2259,7 +2180,6 @@ retry_private:
 				 * doing so.
 				 */
 				requeue_pi_wake_futex(this, &key2, hb2);
-				drop_count++;
 				continue;
 			} else if (ret) {
 				/*
@@ -2280,7 +2200,6 @@ retry_private:
 			}
 		}
 		requeue_futex(this, hb1, hb2, &key2);
-		drop_count++;
 	}
 
 	/*
@@ -2295,15 +2214,6 @@ out_unlock:
 	wake_up_q(&wake_q);
 	hb_waiters_dec(hb2);
 
-	/*
-	 * drop_futex_key_refs() must be called outside the spinlocks. During
-	 * the requeue we moved futex_q's from the hash bucket at key1 to the
-	 * one at key2 and updated their key pointer.  We no longer need to
-	 * hold the references to key1.
-	 */
-	while (--drop_count >= 0)
-		drop_futex_key_refs(&key1);
-
 out_put_keys:
 	put_futex_key(&key2);
 out_put_key1:
@@ -2433,7 +2343,6 @@ retry:
 		ret = 1;
 	}
 
-	drop_futex_key_refs(&q->key);
 	return ret;
 }
 
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index a4ace611f47f..16ee716e8291 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -145,6 +145,13 @@ irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags
 	for_each_action_of_desc(desc, action) {
 		irqreturn_t res;
 
+		/*
+		 * If this IRQ would be threaded under force_irqthreads, mark it so.
+		 */
+		if (irq_settings_can_thread(desc) &&
+		    !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
+			trace_hardirq_threaded();
+
 		trace_irq_handler_entry(irq, action);
 		res = action->handler(irq, action->dev_id);
 		trace_irq_handler_exit(irq, action, res);
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 828cc30774bc..48b5d1b6af4d 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -153,7 +153,9 @@ static void irq_work_run_list(struct llist_head *list)
 		 */
 		flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
 
+		lockdep_irq_work_enter(work);
 		work->func(work);
+		lockdep_irq_work_exit(work);
 		/*
 		 * Clear the BUSY bit and return to the free state if
 		 * no-one else claimed it meanwhile.
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 32406ef0d6a2..0ebf9807d971 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -84,12 +84,39 @@ module_param(lock_stat, int, 0644);
  * to use a raw spinlock - we really dont want the spinlock
  * code to recurse back into the lockdep code...
  */
-static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
+static struct task_struct *__owner;
+
+static inline void lockdep_lock(void)
+{
+	DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+
+	arch_spin_lock(&__lock);
+	__owner = current;
+	current->lockdep_recursion++;
+}
+
+static inline void lockdep_unlock(void)
+{
+	if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current))
+		return;
+
+	current->lockdep_recursion--;
+	__owner = NULL;
+	arch_spin_unlock(&__lock);
+}
+
+static inline bool lockdep_assert_locked(void)
+{
+	return DEBUG_LOCKS_WARN_ON(__owner != current);
+}
+
 static struct task_struct *lockdep_selftest_task_struct;
 
+
 static int graph_lock(void)
 {
-	arch_spin_lock(&lockdep_lock);
+	lockdep_lock();
 	/*
 	 * Make sure that if another CPU detected a bug while
 	 * walking the graph we dont change it (while the other
@@ -97,27 +124,15 @@ static int graph_lock(void)
 	 * dropped already)
 	 */
 	if (!debug_locks) {
-		arch_spin_unlock(&lockdep_lock);
+		lockdep_unlock();
 		return 0;
 	}
-	/* prevent any recursions within lockdep from causing deadlocks */
-	current->lockdep_recursion++;
 	return 1;
 }
 
-static inline int graph_unlock(void)
+static inline void graph_unlock(void)
 {
-	if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
-		/*
-		 * The lockdep graph lock isn't locked while we expect it to
-		 * be, we're confused now, bye!
-		 */
-		return DEBUG_LOCKS_WARN_ON(1);
-	}
-
-	current->lockdep_recursion--;
-	arch_spin_unlock(&lockdep_lock);
-	return 0;
+	lockdep_unlock();
 }
 
 /*
@@ -128,7 +143,7 @@ static inline int debug_locks_off_graph_unlock(void)
 {
 	int ret = debug_locks_off();
 
-	arch_spin_unlock(&lockdep_lock);
+	lockdep_unlock();
 
 	return ret;
 }
@@ -147,6 +162,7 @@ static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES);
 #define KEYHASH_SIZE		(1UL << KEYHASH_BITS)
 static struct hlist_head lock_keys_hash[KEYHASH_SIZE];
 unsigned long nr_lock_classes;
+unsigned long nr_zapped_classes;
 #ifndef CONFIG_DEBUG_LOCKDEP
 static
 #endif
@@ -377,18 +393,31 @@ void lockdep_init_task(struct task_struct *task)
 	task->lockdep_recursion = 0;
 }
 
+/*
+ * Split the recrursion counter in two to readily detect 'off' vs recursion.
+ */
+#define LOCKDEP_RECURSION_BITS	16
+#define LOCKDEP_OFF		(1U << LOCKDEP_RECURSION_BITS)
+#define LOCKDEP_RECURSION_MASK	(LOCKDEP_OFF - 1)
+
 void lockdep_off(void)
 {
-	current->lockdep_recursion++;
+	current->lockdep_recursion += LOCKDEP_OFF;
 }
 EXPORT_SYMBOL(lockdep_off);
 
 void lockdep_on(void)
 {
-	current->lockdep_recursion--;
+	current->lockdep_recursion -= LOCKDEP_OFF;
 }
 EXPORT_SYMBOL(lockdep_on);
 
+static inline void lockdep_recursion_finish(void)
+{
+	if (WARN_ON_ONCE(--current->lockdep_recursion))
+		current->lockdep_recursion = 0;
+}
+
 void lockdep_set_selftest_task(struct task_struct *task)
 {
 	lockdep_selftest_task_struct = task;
@@ -575,6 +604,7 @@ static const char *usage_str[] =
 #include "lockdep_states.h"
 #undef LOCKDEP_STATE
 	[LOCK_USED] = "INITIAL USE",
+	[LOCK_USAGE_STATES] = "IN-NMI",
 };
 #endif
 
@@ -653,7 +683,9 @@ static void print_lock_name(struct lock_class *class)
 
 	printk(KERN_CONT " (");
 	__print_lock_name(class);
-	printk(KERN_CONT "){%s}", usage);
+	printk(KERN_CONT "){%s}-{%hd:%hd}", usage,
+			class->wait_type_outer ?: class->wait_type_inner,
+			class->wait_type_inner);
 }
 
 static void print_lockdep_cache(struct lockdep_map *lock)
@@ -787,6 +819,7 @@ static int count_matching_names(struct lock_class *new_class)
 	return count + 1;
 }
 
+/* used from NMI context -- must be lockless */
 static inline struct lock_class *
 look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
 {
@@ -1070,13 +1103,15 @@ static inline void check_data_structures(void) { }
 
 #endif /* CONFIG_DEBUG_LOCKDEP */
 
+static void init_chain_block_buckets(void);
+
 /*
  * Initialize the lock_classes[] array elements, the free_lock_classes list
  * and also the delayed_free structure.
  */
 static void init_data_structures_once(void)
 {
-	static bool ds_initialized, rcu_head_initialized;
+	static bool __read_mostly ds_initialized, rcu_head_initialized;
 	int i;
 
 	if (likely(rcu_head_initialized))
@@ -1100,6 +1135,7 @@ static void init_data_structures_once(void)
 		INIT_LIST_HEAD(&lock_classes[i].locks_after);
 		INIT_LIST_HEAD(&lock_classes[i].locks_before);
 	}
+	init_chain_block_buckets();
 }
 
 static inline struct hlist_head *keyhashentry(const struct lock_class_key *key)
@@ -1230,6 +1266,8 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
 	WARN_ON_ONCE(!list_empty(&class->locks_before));
 	WARN_ON_ONCE(!list_empty(&class->locks_after));
 	class->name_version = count_matching_names(class);
+	class->wait_type_inner = lock->wait_type_inner;
+	class->wait_type_outer = lock->wait_type_outer;
 	/*
 	 * We use RCU's safe list-add method to make
 	 * parallel walking of the hash-list safe:
@@ -1469,6 +1507,8 @@ static int __bfs(struct lock_list *source_entry,
 	struct circular_queue *cq = &lock_cq;
 	int ret = 1;
 
+	lockdep_assert_locked();
+
 	if (match(source_entry, data)) {
 		*target_entry = source_entry;
 		ret = 0;
@@ -1491,8 +1531,6 @@ static int __bfs(struct lock_list *source_entry,
 
 		head = get_dep_list(lock, offset);
 
-		DEBUG_LOCKS_WARN_ON(!irqs_disabled());
-
 		list_for_each_entry_rcu(entry, head, entry) {
 			if (!lock_accessed(entry)) {
 				unsigned int cq_depth;
@@ -1719,9 +1757,9 @@ unsigned long lockdep_count_forward_deps(struct lock_class *class)
 	this.class = class;
 
 	raw_local_irq_save(flags);
-	arch_spin_lock(&lockdep_lock);
+	lockdep_lock();
 	ret = __lockdep_count_forward_deps(&this);
-	arch_spin_unlock(&lockdep_lock);
+	lockdep_unlock();
 	raw_local_irq_restore(flags);
 
 	return ret;
@@ -1746,9 +1784,9 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
 	this.class = class;
 
 	raw_local_irq_save(flags);
-	arch_spin_lock(&lockdep_lock);
+	lockdep_lock();
 	ret = __lockdep_count_backward_deps(&this);
-	arch_spin_unlock(&lockdep_lock);
+	lockdep_unlock();
 	raw_local_irq_restore(flags);
 
 	return ret;
@@ -2298,18 +2336,6 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
 	return 0;
 }
 
-static void inc_chains(void)
-{
-	if (current->hardirq_context)
-		nr_hardirq_chains++;
-	else {
-		if (current->softirq_context)
-			nr_softirq_chains++;
-		else
-			nr_process_chains++;
-	}
-}
-
 #else
 
 static inline int check_irq_usage(struct task_struct *curr,
@@ -2317,13 +2343,27 @@ static inline int check_irq_usage(struct task_struct *curr,
 {
 	return 1;
 }
+#endif /* CONFIG_TRACE_IRQFLAGS */
 
-static inline void inc_chains(void)
+static void inc_chains(int irq_context)
 {
-	nr_process_chains++;
+	if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
+		nr_hardirq_chains++;
+	else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
+		nr_softirq_chains++;
+	else
+		nr_process_chains++;
 }
 
-#endif /* CONFIG_TRACE_IRQFLAGS */
+static void dec_chains(int irq_context)
+{
+	if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
+		nr_hardirq_chains--;
+	else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT)
+		nr_softirq_chains--;
+	else
+		nr_process_chains--;
+}
 
 static void
 print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
@@ -2622,8 +2662,235 @@ out_bug:
 
 struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
 static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS);
-int nr_chain_hlocks;
 static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
+unsigned long nr_zapped_lock_chains;
+unsigned int nr_free_chain_hlocks;	/* Free chain_hlocks in buckets */
+unsigned int nr_lost_chain_hlocks;	/* Lost chain_hlocks */
+unsigned int nr_large_chain_blocks;	/* size > MAX_CHAIN_BUCKETS */
+
+/*
+ * The first 2 chain_hlocks entries in the chain block in the bucket
+ * list contains the following meta data:
+ *
+ *   entry[0]:
+ *     Bit    15 - always set to 1 (it is not a class index)
+ *     Bits 0-14 - upper 15 bits of the next block index
+ *   entry[1]    - lower 16 bits of next block index
+ *
+ * A next block index of all 1 bits means it is the end of the list.
+ *
+ * On the unsized bucket (bucket-0), the 3rd and 4th entries contain
+ * the chain block size:
+ *
+ *   entry[2] - upper 16 bits of the chain block size
+ *   entry[3] - lower 16 bits of the chain block size
+ */
+#define MAX_CHAIN_BUCKETS	16
+#define CHAIN_BLK_FLAG		(1U << 15)
+#define CHAIN_BLK_LIST_END	0xFFFFU
+
+static int chain_block_buckets[MAX_CHAIN_BUCKETS];
+
+static inline int size_to_bucket(int size)
+{
+	if (size > MAX_CHAIN_BUCKETS)
+		return 0;
+
+	return size - 1;
+}
+
+/*
+ * Iterate all the chain blocks in a bucket.
+ */
+#define for_each_chain_block(bucket, prev, curr)		\
+	for ((prev) = -1, (curr) = chain_block_buckets[bucket];	\
+	     (curr) >= 0;					\
+	     (prev) = (curr), (curr) = chain_block_next(curr))
+
+/*
+ * next block or -1
+ */
+static inline int chain_block_next(int offset)
+{
+	int next = chain_hlocks[offset];
+
+	WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG));
+
+	if (next == CHAIN_BLK_LIST_END)
+		return -1;
+
+	next &= ~CHAIN_BLK_FLAG;
+	next <<= 16;
+	next |= chain_hlocks[offset + 1];
+
+	return next;
+}
+
+/*
+ * bucket-0 only
+ */
+static inline int chain_block_size(int offset)
+{
+	return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3];
+}
+
+static inline void init_chain_block(int offset, int next, int bucket, int size)
+{
+	chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG;
+	chain_hlocks[offset + 1] = (u16)next;
+
+	if (size && !bucket) {
+		chain_hlocks[offset + 2] = size >> 16;
+		chain_hlocks[offset + 3] = (u16)size;
+	}
+}
+
+static inline void add_chain_block(int offset, int size)
+{
+	int bucket = size_to_bucket(size);
+	int next = chain_block_buckets[bucket];
+	int prev, curr;
+
+	if (unlikely(size < 2)) {
+		/*
+		 * We can't store single entries on the freelist. Leak them.
+		 *
+		 * One possible way out would be to uniquely mark them, other
+		 * than with CHAIN_BLK_FLAG, such that we can recover them when
+		 * the block before it is re-added.
+		 */
+		if (size)
+			nr_lost_chain_hlocks++;
+		return;
+	}
+
+	nr_free_chain_hlocks += size;
+	if (!bucket) {
+		nr_large_chain_blocks++;
+
+		/*
+		 * Variable sized, sort large to small.
+		 */
+		for_each_chain_block(0, prev, curr) {
+			if (size >= chain_block_size(curr))
+				break;
+		}
+		init_chain_block(offset, curr, 0, size);
+		if (prev < 0)
+			chain_block_buckets[0] = offset;
+		else
+			init_chain_block(prev, offset, 0, 0);
+		return;
+	}
+	/*
+	 * Fixed size, add to head.
+	 */
+	init_chain_block(offset, next, bucket, size);
+	chain_block_buckets[bucket] = offset;
+}
+
+/*
+ * Only the first block in the list can be deleted.
+ *
+ * For the variable size bucket[0], the first block (the largest one) is
+ * returned, broken up and put back into the pool. So if a chain block of
+ * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be
+ * queued up after the primordial chain block and never be used until the
+ * hlock entries in the primordial chain block is almost used up. That
+ * causes fragmentation and reduce allocation efficiency. That can be
+ * monitored by looking at the "large chain blocks" number in lockdep_stats.
+ */
+static inline void del_chain_block(int bucket, int size, int next)
+{
+	nr_free_chain_hlocks -= size;
+	chain_block_buckets[bucket] = next;
+
+	if (!bucket)
+		nr_large_chain_blocks--;
+}
+
+static void init_chain_block_buckets(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_CHAIN_BUCKETS; i++)
+		chain_block_buckets[i] = -1;
+
+	add_chain_block(0, ARRAY_SIZE(chain_hlocks));
+}
+
+/*
+ * Return offset of a chain block of the right size or -1 if not found.
+ *
+ * Fairly simple worst-fit allocator with the addition of a number of size
+ * specific free lists.
+ */
+static int alloc_chain_hlocks(int req)
+{
+	int bucket, curr, size;
+
+	/*
+	 * We rely on the MSB to act as an escape bit to denote freelist
+	 * pointers. Make sure this bit isn't set in 'normal' class_idx usage.
+	 */
+	BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG);
+
+	init_data_structures_once();
+
+	if (nr_free_chain_hlocks < req)
+		return -1;
+
+	/*
+	 * We require a minimum of 2 (u16) entries to encode a freelist
+	 * 'pointer'.
+	 */
+	req = max(req, 2);
+	bucket = size_to_bucket(req);
+	curr = chain_block_buckets[bucket];
+
+	if (bucket) {
+		if (curr >= 0) {
+			del_chain_block(bucket, req, chain_block_next(curr));
+			return curr;
+		}
+		/* Try bucket 0 */
+		curr = chain_block_buckets[0];
+	}
+
+	/*
+	 * The variable sized freelist is sorted by size; the first entry is
+	 * the largest. Use it if it fits.
+	 */
+	if (curr >= 0) {
+		size = chain_block_size(curr);
+		if (likely(size >= req)) {
+			del_chain_block(0, size, chain_block_next(curr));
+			add_chain_block(curr + req, size - req);
+			return curr;
+		}
+	}
+
+	/*
+	 * Last resort, split a block in a larger sized bucket.
+	 */
+	for (size = MAX_CHAIN_BUCKETS; size > req; size--) {
+		bucket = size_to_bucket(size);
+		curr = chain_block_buckets[bucket];
+		if (curr < 0)
+			continue;
+
+		del_chain_block(bucket, size, chain_block_next(curr));
+		add_chain_block(curr + req, size - req);
+		return curr;
+	}
+
+	return -1;
+}
+
+static inline void free_chain_hlocks(int base, int size)
+{
+	add_chain_block(base, max(size, 2));
+}
 
 struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
 {
@@ -2803,7 +3070,7 @@ static inline int add_chain_cache(struct task_struct *curr,
 	 * disabled to make this an IRQ-safe lock.. for recursion reasons
 	 * lockdep won't complain about its own locking errors.
 	 */
-	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+	if (lockdep_assert_locked())
 		return 0;
 
 	chain = alloc_lock_chain();
@@ -2824,15 +3091,8 @@ static inline int add_chain_cache(struct task_struct *curr,
 	BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));
 	BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
 
-	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
-		chain->base = nr_chain_hlocks;
-		for (j = 0; j < chain->depth - 1; j++, i++) {
-			int lock_id = curr->held_locks[i].class_idx;
-			chain_hlocks[chain->base + j] = lock_id;
-		}
-		chain_hlocks[chain->base + j] = class - lock_classes;
-		nr_chain_hlocks += chain->depth;
-	} else {
+	j = alloc_chain_hlocks(chain->depth);
+	if (j < 0) {
 		if (!debug_locks_off_graph_unlock())
 			return 0;
 
@@ -2841,9 +3101,16 @@ static inline int add_chain_cache(struct task_struct *curr,
 		return 0;
 	}
 
+	chain->base = j;
+	for (j = 0; j < chain->depth - 1; j++, i++) {
+		int lock_id = curr->held_locks[i].class_idx;
+
+		chain_hlocks[chain->base + j] = lock_id;
+	}
+	chain_hlocks[chain->base + j] = class - lock_classes;
 	hlist_add_head_rcu(&chain->entry, hash_head);
 	debug_atomic_inc(chain_lookup_misses);
-	inc_chains();
+	inc_chains(chain->irq_context);
 
 	return 1;
 }
@@ -2987,6 +3254,8 @@ static inline int validate_chain(struct task_struct *curr,
 {
 	return 1;
 }
+
+static void init_chain_block_buckets(void)	{ }
 #endif /* CONFIG_PROVE_LOCKING */
 
 /*
@@ -3429,9 +3698,9 @@ void lockdep_hardirqs_on(unsigned long ip)
 	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
 		return;
 
-	current->lockdep_recursion = 1;
+	current->lockdep_recursion++;
 	__trace_hardirqs_on_caller(ip);
-	current->lockdep_recursion = 0;
+	lockdep_recursion_finish();
 }
 NOKPROBE_SYMBOL(lockdep_hardirqs_on);
 
@@ -3487,7 +3756,7 @@ void trace_softirqs_on(unsigned long ip)
 		return;
 	}
 
-	current->lockdep_recursion = 1;
+	current->lockdep_recursion++;
 	/*
 	 * We'll do an OFF -> ON transition:
 	 */
@@ -3502,7 +3771,7 @@ void trace_softirqs_on(unsigned long ip)
 	 */
 	if (curr->hardirqs_enabled)
 		mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ);
-	current->lockdep_recursion = 0;
+	lockdep_recursion_finish();
 }
 
 /*
@@ -3596,7 +3865,8 @@ lock_used:
 
 static inline unsigned int task_irq_context(struct task_struct *task)
 {
-	return 2 * !!task->hardirq_context + !!task->softirq_context;
+	return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context +
+	       LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context;
 }
 
 static int separate_irq_context(struct task_struct *curr,
@@ -3682,6 +3952,113 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
 	return ret;
 }
 
+static int
+print_lock_invalid_wait_context(struct task_struct *curr,
+				struct held_lock *hlock)
+{
+	if (!debug_locks_off())
+		return 0;
+	if (debug_locks_silent)
+		return 0;
+
+	pr_warn("\n");
+	pr_warn("=============================\n");
+	pr_warn("[ BUG: Invalid wait context ]\n");
+	print_kernel_ident();
+	pr_warn("-----------------------------\n");
+
+	pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
+	print_lock(hlock);
+
+	pr_warn("other info that might help us debug this:\n");
+	lockdep_print_held_locks(curr);
+
+	pr_warn("stack backtrace:\n");
+	dump_stack();
+
+	return 0;
+}
+
+/*
+ * Verify the wait_type context.
+ *
+ * This check validates