1 files changed, 43 insertions, 12 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 23de3719f495..a626211ceb9a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -555,7 +555,7 @@ static bool update_marker_trace(struct trace_array *tr, int enabled)
 	lockdep_assert_held(&event_mutex);
 
 	if (enabled) {
-		if (!list_empty(&tr->marker_list))
+		if (tr->trace_flags & TRACE_ITER(COPY_MARKER))
 			return false;
 
 		list_add_rcu(&tr->marker_list, &marker_copies);
@@ -563,10 +563,10 @@ static bool update_marker_trace(struct trace_array *tr, int enabled)
 		return true;
 	}
 
-	if (list_empty(&tr->marker_list))
+	if (!(tr->trace_flags & TRACE_ITER(COPY_MARKER)))
 		return false;
 
-	list_del_init(&tr->marker_list);
+	list_del_rcu(&tr->marker_list);
 	tr->trace_flags &= ~TRACE_ITER(COPY_MARKER);
 	return true;
 }
@@ -6784,6 +6784,23 @@ char *trace_user_fault_read(struct trace_user_buf_info *tinfo,
 
 	do {
 		/*
+		 * It is possible that something is trying to migrate this
+		 * task. What happens then, is when preemption is enabled,
+		 * the migration thread will preempt this task, try to
+		 * migrate it, fail, then let it run again. That will
+		 * cause this to loop again and never succeed.
+		 * On failures, enabled and disable preemption with
+		 * migration enabled, to allow the migration thread to
+		 * migrate this task.
+		 */
+		if (trys) {
+			preempt_enable_notrace();
+			preempt_disable_notrace();
+			cpu = smp_processor_id();
+			buffer = per_cpu_ptr(tinfo->tbuf, cpu)->buf;
+		}
+
+		/*
 		 * If for some reason, copy_from_user() always causes a context
 		 * switch, this would then cause an infinite loop.
 		 * If this task is preempted by another user space task, it
@@ -8213,6 +8230,18 @@ static inline int get_snapshot_map(struct trace_array *tr) { return 0; }
 static inline void put_snapshot_map(struct trace_array *tr) { }
 #endif
 
+/*
+ * This is called when a VMA is duplicated (e.g., on fork()) to increment
+ * the user_mapped counter without remapping pages.
+ */
+static void tracing_buffers_mmap_open(struct vm_area_struct *vma)
+{
+	struct ftrace_buffer_info *info = vma->vm_file->private_data;
+	struct trace_iterator *iter = &info->iter;
+
+	ring_buffer_map_dup(iter->array_buffer->buffer, iter->cpu_file);
+}
+
 static void tracing_buffers_mmap_close(struct vm_area_struct *vma)
 {
 	struct ftrace_buffer_info *info = vma->vm_file->private_data;
@@ -8232,6 +8261,7 @@ static int tracing_buffers_may_split(struct vm_area_struct *vma, unsigned long a
 }
 
 static const struct vm_operations_struct tracing_buffers_vmops = {
+	.open		= tracing_buffers_mmap_open,
 	.close		= tracing_buffers_mmap_close,
 	.may_split      = tracing_buffers_may_split,
 };
@@ -9337,7 +9367,7 @@ static void setup_trace_scratch(struct trace_array *tr,
 }
 
 static int
-allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size)
+allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, unsigned long size)
 {
 	enum ring_buffer_flags rb_flags;
 	struct trace_scratch *tscratch;
@@ -9392,7 +9422,7 @@ static void free_trace_buffer(struct array_buffer *buf)
 	}
 }
 
-static int allocate_trace_buffers(struct trace_array *tr, int size)
+static int allocate_trace_buffers(struct trace_array *tr, unsigned long size)
 {
 	int ret;
 
@@ -9731,18 +9761,19 @@ static int __remove_instance(struct trace_array *tr)
 
 	list_del(&tr->list);
 
-	/* Disable all the flags that were enabled coming in */
-	for (i = 0; i < TRACE_FLAGS_MAX_SIZE; i++) {
-		if ((1ULL << i) & ZEROED_TRACE_FLAGS)
-			set_tracer_flag(tr, 1ULL << i, 0);
-	}
-
 	if (printk_trace == tr)
 		update_printk_trace(&global_trace);
 
+	/* Must be done before disabling all the flags */
 	if (update_marker_trace(tr, 0))
 		synchronize_rcu();
 
+	/* Disable all the flags that were enabled coming in */
+	for (i = 0; i < TRACE_FLAGS_MAX_SIZE; i++) {
+		if ((1ULL << i) & ZEROED_TRACE_FLAGS)
+			set_tracer_flag(tr, 1ULL << i, 0);
+	}
+
 	tracing_set_nop(tr);
 	clear_ftrace_function_probes(tr);
 	event_trace_del_tracer(tr);
@@ -10756,7 +10787,7 @@ __init static void enable_instances(void)
 
 __init static int tracer_alloc_buffers(void)
 {
-	int ring_buf_size;
+	unsigned long ring_buf_size;
 	int ret = -ENOMEM;