1 files changed, 47 insertions, 5 deletions

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 56f69cc53ddc..eda8114ef793 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4681,6 +4681,17 @@ EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
 static atomic_t cross_gen_id; /* Can be wrapped */
 
 /*
+ * Make an entry of the ring buffer invalid.
+ */
+static inline void invalidate_xhlock(struct hist_lock *xhlock)
+{
+	/*
+	 * Normally, xhlock->hlock.instance must be !NULL.
+	 */
+	xhlock->hlock.instance = NULL;
+}
+
+/*
  * Lock history stacks; we have 3 nested lock history stacks:
  *
  *   Hard IRQ
@@ -4712,14 +4723,28 @@ static atomic_t cross_gen_id; /* Can be wrapped */
  */
 void crossrelease_hist_start(enum xhlock_context_t c)
 {
-	if (current->xhlocks)
-		current->xhlock_idx_hist[c] = current->xhlock_idx;
+	struct task_struct *cur = current;
+
+	if (cur->xhlocks) {
+		cur->xhlock_idx_hist[c] = cur->xhlock_idx;
+		cur->hist_id_save[c] = cur->hist_id;
+	}
 }
 
 void crossrelease_hist_end(enum xhlock_context_t c)
 {
-	if (current->xhlocks)
-		current->xhlock_idx = current->xhlock_idx_hist[c];
+	struct task_struct *cur = current;
+
+	if (cur->xhlocks) {
+		unsigned int idx = cur->xhlock_idx_hist[c];
+		struct hist_lock *h = &xhlock(idx);
+
+		cur->xhlock_idx = idx;
+
+		/* Check if the ring was overwritten. */
+		if (h->hist_id != cur->hist_id_save[c])
+			invalidate_xhlock(h);
+	}
 }
 
 static int cross_lock(struct lockdep_map *lock)
@@ -4765,6 +4790,7 @@ static inline int depend_after(struct held_lock *hlock)
  * Check if the xhlock is valid, which would be false if,
  *
  *    1. Has not used after initializaion yet.
+ *    2. Got invalidated.
  *
  * Remind hist_lock is implemented as a ring buffer.
  */
@@ -4796,6 +4822,7 @@ static void add_xhlock(struct held_lock *hlock)
 
 	/* Initialize hist_lock's members */
 	xhlock->hlock = *hlock;
+	xhlock->hist_id = current->hist_id++;
 
 	xhlock->trace.nr_entries = 0;
 	xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES;
@@ -4934,6 +4961,7 @@ static int commit_xhlock(struct cross_lock *xlock, struct hist_lock *xhlock)
 static void commit_xhlocks(struct cross_lock *xlock)
 {
 	unsigned int cur = current->xhlock_idx;
+	unsigned int prev_hist_id = xhlock(cur).hist_id;
 	unsigned int i;
 
 	if (!graph_lock())
@@ -4952,6 +4980,17 @@ static void commit_xhlocks(struct cross_lock *xlock)
 			break;
 
 		/*
+		 * Filter out the cases that the ring buffer was
+		 * overwritten and the previous entry has a bigger
+		 * hist_id than the following one, which is impossible
+		 * otherwise.
+		 */
+		if (unlikely(before(xhlock->hist_id, prev_hist_id)))
+			break;
+
+		prev_hist_id = xhlock->hist_id;
+
+		/*
 		 * commit_xhlock() returns 0 with graph_lock already
 		 * released if fail.
 		 */
@@ -5024,9 +5063,12 @@ void lockdep_init_task(struct task_struct *task)
 	int i;
 
 	task->xhlock_idx = UINT_MAX;
+	task->hist_id = 0;
 
-	for (i = 0; i < XHLOCK_CTX_NR; i++)
+	for (i = 0; i < XHLOCK_CTX_NR; i++) {
 		task->xhlock_idx_hist[i] = UINT_MAX;
+		task->hist_id_save[i] = 0;
+	}
 
 	task->xhlocks = kzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR,
 				GFP_KERNEL);