[PATCH 0/2] selftests/mm: Add -Wunreachable-code and fix warnings

[PATCH 0/2] selftests/mm: Add -Wunreachable-code and fix warnings

[Muhammad Usama Anjum]

This series is trimmed down version of previous more generic series[1].
In this new series, only -wunreachable-code flag is being added and dead
code is being removed from generated warnings.

[1] https://lore.kernel.org/all/20250822082145.4145617-1-usama.anjum@collabora.com

Muhammad Usama Anjum (2):
  selftests/mm: Add -Wunreachable-code and fix warnings
  selftests/mm: protection_keys: Fix dead code

 tools/testing/selftests/mm/Makefile                | 1 +
 tools/testing/selftests/mm/hmm-tests.c             | 5 ++---
 tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 +-
 tools/testing/selftests/mm/protection_keys.c       | 4 +---
 tools/testing/selftests/mm/split_huge_page_test.c  | 2 +-
 5 files changed, 6 insertions(+), 8 deletions(-)

-- 
2.47.3

[PATCH 1/2] selftests/mm: Add -Wunreachable-code and fix warnings

[Muhammad Usama Anjum]

Enable -Wunreachable-code flag to catch dead code and fix them.

1. Remove the dead code and write a comment instead:
hmm-tests.c:2033:3: warning: code will never be executed
[-Wunreachable-code]
                perror("Should not reach this\n");
                ^~~~~~

2. ksft_exit_fail_msg() calls exit(). So cleanup isn't done. Replace it
   with ksft_print_msg().
split_huge_page_test.c:301:3: warning: code will never be executed
[-Wunreachable-code]
                goto cleanup;
                ^~~~~~~~~~~~

3. Remove duplicate inline.
pkey_sighandler_tests.c:44:15: warning: duplicate 'inline' declaration
specifier [-Wduplicate-decl-specifier]
static inline __always_inline

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 tools/testing/selftests/mm/Makefile                | 1 +
 tools/testing/selftests/mm/hmm-tests.c             | 5 ++---
 tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 +-
 tools/testing/selftests/mm/split_huge_page_test.c  | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 5a1dee50b8987..eaf9312097f7b 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -34,6 +34,7 @@ endif
 MAKEFLAGS += --no-builtin-rules
 
 CFLAGS = -Wall -O2 -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
+CFLAGS += -Wunreachable-code
 LDLIBS = -lrt -lpthread -lm
 
 # Some distributions (such as Ubuntu) configure GCC so that _FORTIFY_SOURCE is
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index 1325de70f44fc..25045536f4707 100644
--- a/tools/testing/selftests/mm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -2030,11 +2030,10 @@ TEST_F(hmm, hmm_cow_in_device)
 	if (pid == -1)
 		ASSERT_EQ(pid, 0);
 	if (!pid) {
-		/* Child process waitd for SIGTERM from the parent. */
+		/* Child process waits for SIGTERM from the parent. */
 		while (1) {
 		}
-		perror("Should not reach this\n");
-		exit(0);
+		/* Should not reach this */
 	}
 	/* Parent process writes to COW pages(s) and gets a
 	 * new copy in system. In case of device private pages,
diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index b5e076a564c95..302fef54049c8 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -41,7 +41,7 @@ static siginfo_t siginfo = {0};
  * syscall will attempt to access the PLT in order to call a library function
  * which is protected by MPK 0 which we don't have access to.
  */
-static inline __always_inline
+static __always_inline
 long syscall_raw(long n, long a1, long a2, long a3, long a4, long a5, long a6)
 {
 	unsigned long ret;
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 7731191cc8e9b..743af3c051905 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -510,7 +510,7 @@ static void split_file_backed_thp(int order)
 
 	status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
 	if (status >= INPUT_MAX) {
-		ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n");
+		ksft_print_msg("Fail to create file-backed THP split testing file\n");
 		goto cleanup;
 	}
 
-- 
2.47.3

[PATCH 2/2] selftests/mm: protection_keys: Fix dead code

[Muhammad Usama Anjum]

The while loop doesn't execute and following warning gets generated:

protection_keys.c:561:15: warning: code will never be executed
[-Wunreachable-code]
                int rpkey = alloc_random_pkey();

Let's enable the while loop such that it gets executed nr_iterations
times. Simplify the code a bit as well.

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 tools/testing/selftests/mm/protection_keys.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 23ebec367015f..6281d4c61b50e 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -557,13 +557,11 @@ int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
 	int nr_iterations = random() % 100;
 	int ret;
 
-	while (0) {
+	while (nr_iterations-- >= 0) {
 		int rpkey = alloc_random_pkey();
 		ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey);
 		dprintf1("sys_mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n",
 				ptr, size, orig_prot, pkey, ret);
-		if (nr_iterations-- < 0)
-			break;
 
 		dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx"
 			" shadow: 0x%016llx\n",
-- 
2.47.3

Re: [PATCH 1/2] selftests/mm: Add -Wunreachable-code and fix warnings

[David Hildenbrand]

On 12.09.25 14:30, Muhammad Usama Anjum wrote:
> Enable -Wunreachable-code flag to catch dead code and fix them.
> 
> 1. Remove the dead code and write a comment instead:
> hmm-tests.c:2033:3: warning: code will never be executed
> [-Wunreachable-code]
>                  perror("Should not reach this\n");
>                  ^~~~~~
> 
> 2. ksft_exit_fail_msg() calls exit(). So cleanup isn't done. Replace it
>     with ksft_print_msg().
> split_huge_page_test.c:301:3: warning: code will never be executed
> [-Wunreachable-code]
>                  goto cleanup;
>                  ^~~~~~~~~~~~
> 
> 3. Remove duplicate inline.
> pkey_sighandler_tests.c:44:15: warning: duplicate 'inline' declaration
> specifier [-Wduplicate-decl-specifier]
> static inline __always_inline
> 
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---


Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers

David / dhildenb

Re: [PATCH 2/2] selftests/mm: protection_keys: Fix dead code

[Zi Yan]

On 12 Sep 2025, at 8:30, Muhammad Usama Anjum wrote:

> The while loop doesn't execute and following warning gets generated:
>
> protection_keys.c:561:15: warning: code will never be executed
> [-Wunreachable-code]
>                 int rpkey = alloc_random_pkey();
>
> Let's enable the while loop such that it gets executed nr_iterations
> times. Simplify the code a bit as well.
>
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---
>  tools/testing/selftests/mm/protection_keys.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>

LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

Re: [PATCH 1/2] selftests/mm: Add -Wunreachable-code and fix warnings

[Zi Yan]

On 12 Sep 2025, at 8:30, Muhammad Usama Anjum wrote:

> Enable -Wunreachable-code flag to catch dead code and fix them.
>
> 1. Remove the dead code and write a comment instead:
> hmm-tests.c:2033:3: warning: code will never be executed
> [-Wunreachable-code]
>                 perror("Should not reach this\n");
>                 ^~~~~~
>
> 2. ksft_exit_fail_msg() calls exit(). So cleanup isn't done. Replace it
>    with ksft_print_msg().
> split_huge_page_test.c:301:3: warning: code will never be executed
> [-Wunreachable-code]
>                 goto cleanup;
>                 ^~~~~~~~~~~~
>
> 3. Remove duplicate inline.
> pkey_sighandler_tests.c:44:15: warning: duplicate 'inline' declaration
> specifier [-Wduplicate-decl-specifier]
> static inline __always_inline
>
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---
>  tools/testing/selftests/mm/Makefile                | 1 +
>  tools/testing/selftests/mm/hmm-tests.c             | 5 ++---
>  tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 +-
>  tools/testing/selftests/mm/split_huge_page_test.c  | 2 +-
>  4 files changed, 5 insertions(+), 5 deletions(-)
>
LGTM. Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi