Re: [PATCH] selftests/mm: add missing mmap() return checks in pkey tests

[Lorenzo Stoakes]

Hmm you're sending this separete from the other MAP_FAILED checks, and not
referencing that in any way? (original patch at [0]).

Please just send this as a 2 patch series _with a cover letter_ and both patches
in-reply-to the cover letter.

Also make sure to propagate tags correctly.

[0]:https://lore.kernel.org/all/20260513095609.789935-1-lihongfu@xxxxxxxxxx/

On Mon, May 18, 2026 at 04:21:20PM +0800, Hongfu Li wrote:
> Several mmap() calls lack error checks and would crash on failure.
> Add the missing checks. Also replace bare (void *)-1 with the

Well you're assert()'ing so you're causing a crash on failure anyway?

I'd just say that you are adding missing checks against the mmap() return value,
as well as improving readability and consistency by replacing (void *)-1 with
MAP_FAILED in instances where that was used rather than MAP_FAILED.

> standard MAP_FAILED macro in protection_keys.c for consistency.
>
> Signed-off-by: Hongfu Li <lihongfu@xxxxxxxxxx>

Some comments below.

> ---
>  tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 ++
>  tools/testing/selftests/mm/protection_keys.c       | 9 +++++----
>  2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> index 302fef54049c..4637809192f9 100644
> --- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
> +++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> @@ -317,6 +317,7 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
>  	/* Set up alternate signal stack that will use the default MPK */
>  	sigstack.ss_sp = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE,
>  			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +	assert(sigstack.ss_sp != MAP_FAILED);

Why not pkey_assert()?

>  	sigstack.ss_flags = 0;
>  	sigstack.ss_size = STACK_SIZE;
>
> @@ -490,6 +491,7 @@ static void test_pkru_sigreturn(void)
>  	/* Set up alternate signal stack that will use the default MPK */
>  	sigstack.ss_sp = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE,
>  			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +	assert(sigstack.ss_sp != MAP_FAILED);

Why not pkey_assert()?

>  	sigstack.ss_flags = 0;
>  	sigstack.ss_size = STACK_SIZE;
>
> diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
> index 2085982dba69..d53bdc540a74 100644
> --- a/tools/testing/selftests/mm/protection_keys.c
> +++ b/tools/testing/selftests/mm/protection_keys.c
> @@ -667,7 +667,7 @@ static void *malloc_pkey_with_mprotect(long size, int prot, u16 pkey)
>  			size, prot, pkey);
>  	pkey_assert(pkey < NR_PKEYS);
>  	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
> -	pkey_assert(ptr != (void *)-1);
> +	pkey_assert(ptr != MAP_FAILED);
>  	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
>  	pkey_assert(!ret);
>  	record_pkey_malloc(ptr, size, prot);
> @@ -690,7 +690,7 @@ static void *malloc_pkey_anon_huge(long size, int prot, u16 pkey)
>  	 */
>  	size = ALIGN_UP(size, HPAGE_SIZE * 2);
>  	ptr = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
> -	pkey_assert(ptr != (void *)-1);
> +	pkey_assert(ptr != MAP_FAILED);
>  	record_pkey_malloc(ptr, size, prot);
>  	mprotect_pkey(ptr, size, prot, pkey);
>
> @@ -770,7 +770,7 @@ static void *malloc_pkey_hugetlb(long size, int prot, u16 pkey)
>  	size = ALIGN_UP(size, HPAGE_SIZE * 2);
>  	pkey_assert(pkey < NR_PKEYS);
>  	ptr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
> -	pkey_assert(ptr != (void *)-1);
> +	pkey_assert(ptr != MAP_FAILED);
>  	mprotect_pkey(ptr, size, prot, pkey);
>
>  	record_pkey_malloc(ptr, size, prot);
> @@ -1217,6 +1217,7 @@ static void arch_force_pkey_reg_init(void)
>  	 * doing the XSAVE size enumeration dance.
>  	 */
>  	buf = mmap(NULL, 1*MB, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
> +	pkey_assert(buf != MAP_FAILED);
>
>  	/* These __builtins require compiling with -mxsave */
>
> @@ -1775,7 +1776,7 @@ int main(void)
>  		printf("running PKEY tests for unsupported CPU/OS\n");
>
>  		ptr  = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
> -		assert(ptr != (void *)-1);
> +		assert(ptr != MAP_FAILED);

Probably best to convert to pkey_assert() at the same time?

>  		test_mprotect_pkey_on_unsupported_cpu(ptr, 1);
>  		exit(0);
>  	}
> --
> 2.25.1
>

Cheers, Lorenzo