[PATCH v2] mm/gup_test: GUP_TEST depends on DEBUG_FS

[Barry Song <song.bao.hua@hisilicon.com>]

Without DEBUG_FS, all the code in gup_test becomes meaningless. For sure
kernel provides debugfs stub while DEBUG_FS is disabled, but the point
here is that GUP_TEST can do nothing without DEBUG_FS.

Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Suggested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
---
 -v2:
 add comment as a prompt to users as commented by John and Randy, thanks!

 mm/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index 01b0ae0cd9d3..a7ff0d31afd5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -836,6 +836,7 @@ config PERCPU_STATS
 
 config GUP_TEST
 	bool "Enable infrastructure for get_user_pages()-related unit tests"
+	depends on DEBUG_FS
 	help
 	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
 	  to make ioctl calls that can launch kernel-based unit tests for
@@ -853,6 +854,9 @@ config GUP_TEST
 
 	  See tools/testing/selftests/vm/gup_test.c
 
+comment "GUP_TEST needs to have DEBUG_FS enabled"
+	depends on !GUP_TEST && !DEBUG_FS
+
 config GUP_GET_PTE_LOW_HIGH
 	bool
 
-- 
2.25.1