selftests/mm: fix invocation of tests that are run via shell scripts

We cannot depend upon git to reliably retain the executable bit on shell
scripts, or so I was told several years ago while working on this same
run_vmtests.sh script. And sure enough, things such as test_hmm.sh are
lately failing to run, due to lacking execute permissions.

Fix this by explicitly adding "bash" to each of the shell script
invocations. Leave fixing the overall approach to another day.

Link: https://lkml.kernel.org/r/20230606071637.267103-5-jhubbard@nvidia.comSigned-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/run_vmtests.sh

@@ -244,18 +244,18 @@ if [ $VADDR64 -ne 0 ]; then
 	if [ "$ARCH" == "$ARCH_ARM64" ]; then
 		echo 6 > /proc/sys/vm/nr_hugepages
 	fi
-	CATEGORY="hugevm" run_test ./va_high_addr_switch.sh
+	CATEGORY="hugevm" run_test bash ./va_high_addr_switch.sh
 	if [ "$ARCH" == "$ARCH_ARM64" ]; then
 		echo $prev_nr_hugepages > /proc/sys/vm/nr_hugepages
 	fi
 fi # VADDR64
 
 # vmalloc stability smoke test
-CATEGORY="vmalloc" run_test ./test_vmalloc.sh smoke
+CATEGORY="vmalloc" run_test bash ./test_vmalloc.sh smoke
 
 CATEGORY="mremap" run_test ./mremap_dontunmap
 
-CATEGORY="hmm" run_test ./test_hmm.sh smoke
+CATEGORY="hmm" run_test bash ./test_hmm.sh smoke
 
 # MADV_POPULATE_READ and MADV_POPULATE_WRITE tests
 CATEGORY="madv_populate" run_test ./madv_populate