Selftests built with O= store generated files by default under
$(objtree)/kselftest. Those files are not removed by mrproper today, so
stale generated artifacts can survive across builds and be reused
unexpectedly.

Add kselftest to MRPROPER_FILES, so that the default kselftest output
directory as part of mrproper target.

Signed-off-by: Ricardo B. Marlière <rbm@suse.com>
---
 Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Makefile b/Makefile
index c9b7bee102e8..91e6ec790a0f 100644
--- a/Makefile
+++ b/Makefile
@@ -1662,6 +1662,7 @@ MRPROPER_FILES += include/config include/generated          \
 		  debian snap tar-install PKGBUILD pacman \
 		  .config .config.old .version \
 		  Module.symvers \
+		  kselftest \
 		  certs/signing_key.pem \
 		  certs/x509.genkey \
 		  vmlinux-gdb.py \

-- 
2.53.0