kmemleak-test: fix kmemleak_test.c build logic

kmemleak-test.c was moved to the samples directory in 1abbef4f
("mm,kmemleak-test.c: move kmemleak-test.c to samples dir").

If CONFIG_DEBUG_KMEMLEAK_TEST=m and CONFIG_SAMPLES is unset,
kmemleak-test.c will be unnecessarily compiled.

So move the entry for CONFIG_DEBUG_KMEMLEAK_TEST from mm/Kconfig and add a
new CONFIG_SAMPLE_KMEMLEAK in samples/ to control whether kmemleak-test.c
is built or not.

Link: https://lkml.kernel.org/r/20230330060904.292975-1-gehao@kylinos.cn
Fixes: 1abbef4f ("mm,kmemleak-test.c: move kmemleak-test.c to samples dir")
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Finn Behrens <me@kloenk.dev>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: Ye Xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/Kconfig.debug

@@ -249,14 +249,6 @@ config DEBUG_KMEMLEAK_MEM_POOL_SIZE
 	  fully initialised, this memory pool acts as an emergency one
 	  if slab allocations fail.
 
-config DEBUG_KMEMLEAK_TEST
-	tristate "Simple test for the kernel memory leak detector"
-	depends on DEBUG_KMEMLEAK && m
-	help
-	  This option enables a module that explicitly leaks memory.
-
-	  If unsure, say N.
-
 config DEBUG_KMEMLEAK_DEFAULT_OFF
 	bool "Default kmemleak to off"
 	depends on DEBUG_KMEMLEAK

samples/Kconfig

@@ -273,6 +273,13 @@ config SAMPLE_CORESIGHT_SYSCFG
 	  This demonstrates how a user may create their own CoreSight
 	  configurations and easily load them into the system at runtime.
 
+config SAMPLE_KMEMLEAK
+        tristate "Simple test for the kernel memory leak detector"
+        depends on DEBUG_KMEMLEAK && m
+        help
+          Build a sample program which have explicitly leaks memory to test
+          kmemleak
+
 source "samples/rust/Kconfig"
 
 endif # SAMPLES

samples/Makefile

@@ -33,7 +33,7 @@ subdir-$(CONFIG_SAMPLE_VFS)		+= vfs
 obj-$(CONFIG_SAMPLE_INTEL_MEI)		+= mei/
 subdir-$(CONFIG_SAMPLE_WATCHDOG)	+= watchdog
 subdir-$(CONFIG_SAMPLE_WATCH_QUEUE)	+= watch_queue
-obj-$(CONFIG_DEBUG_KMEMLEAK_TEST)	+= kmemleak/
+obj-$(CONFIG_SAMPLE_KMEMLEAK)		+= kmemleak/
 obj-$(CONFIG_SAMPLE_CORESIGHT_SYSCFG)	+= coresight/
 obj-$(CONFIG_SAMPLE_FPROBE)		+= fprobe/
 obj-$(CONFIG_SAMPLES_RUST)		+= rust/

samples/kmemleak/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 
-obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
+obj-$(CONFIG_SAMPLE_KMEMLEAK) += kmemleak-test.o