2 files changed, 8 insertions, 2 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 9e06b7f5ecf1..1b4afd2e6ca0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -994,13 +994,16 @@ config FAULT_INJECTION_STACKTRACE_FILTER
 
 config LATENCYTOP
         bool "Latency measuring infrastructure"
+        depends on HAVE_LATENCYTOP_SUPPORT
+        depends on DEBUG_KERNEL
+        depends on STACKTRACE_SUPPORT
+        depends on PROC_FS
         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
         select KALLSYMS
         select KALLSYMS_ALL
         select STACKTRACE
         select SCHEDSTATS
         select SCHED_DEBUG
-        depends on HAVE_LATENCYTOP_SUPPORT
         help
           Enable this option if you want to use the LatencyTOP tool
           to find out which userspace is blocking on what kernel operations.
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index e907858498a6..5b7d4623f0b7 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -625,6 +625,8 @@ EXPORT_SYMBOL(radix_tree_tag_get);
  *
  * The function returns number of leaves where the tag was set and sets
  * *first_indexp to the first unscanned index.
+ * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must
+ * be prepared to handle that.
  */
 unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
                 unsigned long *first_indexp, unsigned long last_index,
@@ -675,7 +677,8 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
 next:
                 /* Go to next item at level determined by 'shift' */
                 index = ((index >> shift) + 1) << shift;
-                if (index > last_index)
+                /* Overflow can happen when last_index is ~0UL... */
+                if (index > last_index || !index)
                         break;
                 if (tagged >= nr_to_tag)
                         break;