--- zzzz-none-000/linux-3.10.107/drivers/md/persistent-data/Kconfig	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/md/persistent-data/Kconfig	2021-02-04 17:41:59.000000000 +0000
@@ -6,3 +6,13 @@
        ---help---
 	 Library providing immutable on-disk data structure support for
 	 device-mapper targets such as the thin provisioning target.
+
+config DM_DEBUG_BLOCK_STACK_TRACING
+       bool "Keep stack trace of persistent data block lock holders"
+       depends on STACKTRACE_SUPPORT && DM_PERSISTENT_DATA
+       select STACKTRACE
+       ---help---
+	 Enable this for messages that may help debug problems with the
+	 block manager locking used by thin provisioning and caching.
+
+	 If unsure, say N.