[PATCH v10 0/6] selftests/mm: refactor pkey helpers and fix mmap error handling

[PATCH v10 0/6] selftests/mm: refactor pkey helpers and fix mmap error handling

[Hongfu Li]

The main changes in this series are to refactor shared tracing and assertion
helpers into a common file, unify both pkey selftests on pkey_assert() and
per-test tracing for consistent diagnostics, and add missing mmap() return
checks with MAP_FAILED used throughout for readability and consistency.

Hongfu Li (6):
  selftests/mm: move pkey selftest helpers to pkey_util.c
  selftests/mm: unify pkey sighandler selftest assertions and tracing
  selftests/mm: use pkey_assert on clone_raw failure in pkey test
  selftests/mm: add missing mmap() return checks in pkey tests
  selftests/mm: add missing pthread_create() return checks in pkey tests
  selftests/mm: fix clone cleartid race in pkey sighandler tests

 tools/testing/selftests/mm/pkey-helpers.h     |   4 +-
 tools/testing/selftests/mm/pkey-powerpc.h     |   2 +-
 .../selftests/mm/pkey_sighandler_tests.c      | 115 ++++++++++--------
 tools/testing/selftests/mm/pkey_util.c        |  90 ++++++++++++++
 tools/testing/selftests/mm/protection_keys.c  |  99 ++-------------
 5 files changed, 165 insertions(+), 145 deletions(-)

---
v10:
- Add patch 6/6 to fix a pre-existing cleartid race: remove unused
  settid/cleartid clone flags and wait for the clone child to exit in
  the sigsegv test.
v9:
- In patch 1/5, define test_nr, iteration_nr and dprint_in_signal in
  pkey_util.c and remove them from protection_keys.c and
  pkey_sighandler_tests.c.
- In patch 1/5, cat_into_file() used the wrong argument in the open()
  failure message; print file instead of str. Update the commit message
  accordingly.
- In patch 2/5, align clone_raw() continuation lines to the opening parenthesis.
- In patch 5/5, set errno from pthread_create() return value before
  pkey_assert(0) on thread creation failure.
- Add Acked-by, Reviewed-by and Tested-by tags to each patch.
v8:
- No code changes (relative to v7).
- Updated Cc list: added developers identified via `git blame` and
  `git log` on tools/testing/selftests/mm/pkey*
v7:
- As previously suggested, wait for v7.2-rc1 and rebased the whole series
  on top of it. No functional code changes.
v6:
- Add missing pthread_create() return checks (new patch 5/5).
- In patch 2/5, call tracing_off() at the start of test_pkru_sigreturn
  before the SIGSEGV handler is reset to SIG_DFL, to avoid leaving ftrace
  enabled on crash.
v5:
- Use ret instead of child_pid to hold the return value of clone_raw().
- Make tracing_on(), tracing_off() non-static.
  Remove cat_into_file() declaration from pkey-helpers.h.
v4:
- Base changes on top of the latest mm-unstable branch.
- Split the first patch into three:
  patch 1: move pkey selftest helpers to shared code;
  patch 2: unify sighandler selftest assertions and per-test tracing;
  patch 3: use pkey_assert() on clone_raw() failure.
- Use ksft_exit_fail_perror() in main() for mmap() failure.
v3:
- Use pkey_assert() for remaining sigaction() and clone_raw() error
  checks for consistency.
v2:
- Update commit message
- Move shared tracing and assertion helpers to a common file,
  replace assert() with pkey_assert() in sighandler tests
- Drop assert() from main() in protection_keys.c and add a proper error
  message instead.
- Link to v1: https://lore.kernel.org/all/20260518082120.3890552-1-lihongfu@kylinos.cn/
-- 
2.25.1

[PATCH v10 1/6] selftests/mm: move pkey selftest helpers to pkey_util.c

[Hongfu Li]

Move pkey selftest debugging helpers into shared code so both pkey
selftests can use the same tracing and abort-hook logic. Also fix
cat_into_file() to print file, not str, in the open() failure message.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Tested-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 tools/testing/selftests/mm/pkey-helpers.h    |  4 +-
 tools/testing/selftests/mm/pkey_util.c       | 90 ++++++++++++++++++++
 tools/testing/selftests/mm/protection_keys.c | 87 -------------------
 3 files changed, 93 insertions(+), 88 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey-helpers.h b/tools/testing/selftests/mm/pkey-helpers.h
index 2c377f4e9df1..46a8a1878dc1 100644
--- a/tools/testing/selftests/mm/pkey-helpers.h
+++ b/tools/testing/selftests/mm/pkey-helpers.h
@@ -68,7 +68,9 @@ static inline void sigsafe_printf(const char *format, ...)
 #define dprintf3(args...) dprintf_level(3, args)
 #define dprintf4(args...) dprintf_level(4, args)
 
-extern void abort_hooks(void);
+void tracing_on(void);
+void tracing_off(void);
+void abort_hooks(void);
 #define pkey_assert(condition) do {		\
 	if (!(condition)) {			\
 		dprintf0("# assert() at %s::%d test_nr: %d iteration: %d\n", \
diff --git a/tools/testing/selftests/mm/pkey_util.c b/tools/testing/selftests/mm/pkey_util.c
index 255b332f7a08..fbef3cd45447 100644
--- a/tools/testing/selftests/mm/pkey_util.c
+++ b/tools/testing/selftests/mm/pkey_util.c
@@ -2,9 +2,99 @@
 #define __SANE_USERSPACE_TYPES__
 #include <sys/syscall.h>
 #include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
 
 #include "pkey-helpers.h"
 
+int iteration_nr = 1;
+int test_nr;
+int dprint_in_signal;
+
+#if CONTROL_TRACING > 0
+static void cat_into_file(char *str, char *file)
+{
+	int fd = open(file, O_RDWR);
+	int ret;
+
+	dprintf2("%s(): writing '%s' to '%s'\n", __func__, str, file);
+	/*
+	 * these need to be raw because they are called under
+	 * pkey_assert()
+	 */
+	if (fd < 0) {
+		fprintf(stderr, "error opening '%s'\n", file);
+		perror("error: ");
+		exit(__LINE__);
+	}
+
+	ret = write(fd, str, strlen(str));
+	if (ret != strlen(str)) {
+		perror("write to file failed");
+		fprintf(stderr, "filename: '%s' str: '%s'\n", file, str);
+		exit(__LINE__);
+	}
+	close(fd);
+}
+
+static int warned_tracing;
+static int tracing_root_ok(void)
+{
+	if (geteuid() != 0) {
+		if (!warned_tracing)
+			fprintf(stderr, "WARNING: not run as root, "
+					"can not do tracing control\n");
+		warned_tracing = 1;
+		return 0;
+	}
+	return 1;
+}
+#endif
+
+void tracing_on(void)
+{
+#if CONTROL_TRACING > 0
+#define TRACEDIR "/sys/kernel/tracing"
+	char pidstr[32];
+
+	if (!tracing_root_ok())
+		return;
+
+	sprintf(pidstr, "%d", getpid());
+	cat_into_file("0", TRACEDIR "/tracing_on");
+	cat_into_file("\n", TRACEDIR "/trace");
+	if (1) {
+		cat_into_file("function_graph", TRACEDIR "/current_tracer");
+		cat_into_file("1", TRACEDIR "/options/funcgraph-proc");
+	} else {
+		cat_into_file("nop", TRACEDIR "/current_tracer");
+	}
+	cat_into_file(pidstr, TRACEDIR "/set_ftrace_pid");
+	cat_into_file("1", TRACEDIR "/tracing_on");
+	dprintf1("enabled tracing\n");
+#endif
+}
+
+void tracing_off(void)
+{
+#if CONTROL_TRACING > 0
+	if (!tracing_root_ok())
+		return;
+	cat_into_file("0", "/sys/kernel/tracing/tracing_on");
+#endif
+}
+
+void abort_hooks(void)
+{
+	fflush(stdout);
+	fprintf(stderr, "running %s()...\n", __func__);
+	tracing_off();
+#ifdef SLEEP_ON_ABORT
+	sleep(SLEEP_ON_ABORT);
+#endif
+}
+
 int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
 {
 	int ret = syscall(SYS_pkey_alloc, flags, init_val);
diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 9a6d954ee371..be4a0470cc61 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -49,11 +49,7 @@
 #include "hugepage_settings.h"
 #include "pkey-helpers.h"
 
-int iteration_nr = 1;
-int test_nr;
-
 u64 shadow_pkey_reg;
-int dprint_in_signal;
 
 noinline int read_ptr(int *ptr)
 {
@@ -62,89 +58,6 @@ noinline int read_ptr(int *ptr)
 	return *ptr;
 }
 
-#if CONTROL_TRACING > 0
-static void cat_into_file(char *str, char *file)
-{
-	int fd = open(file, O_RDWR);
-	int ret;
-
-	dprintf2("%s(): writing '%s' to '%s'\n", __func__, str, file);
-	/*
-	 * these need to be raw because they are called under
-	 * pkey_assert()
-	 */
-	if (fd < 0) {
-		fprintf(stderr, "error opening '%s'\n", str);
-		perror("error: ");
-		exit(__LINE__);
-	}
-
-	ret = write(fd, str, strlen(str));
-	if (ret != strlen(str)) {
-		perror("write to file failed");
-		fprintf(stderr, "filename: '%s' str: '%s'\n", file, str);
-		exit(__LINE__);
-	}
-	close(fd);
-}
-
-static int warned_tracing;
-static int tracing_root_ok(void)
-{
-	if (geteuid() != 0) {
-		if (!warned_tracing)
-			fprintf(stderr, "WARNING: not run as root, "
-					"can not do tracing control\n");
-		warned_tracing = 1;
-		return 0;
-	}
-	return 1;
-}
-#endif
-
-static void tracing_on(void)
-{
-#if CONTROL_TRACING > 0
-#define TRACEDIR "/sys/kernel/tracing"
-	char pidstr[32];
-
-	if (!tracing_root_ok())
-		return;
-
-	sprintf(pidstr, "%d", getpid());
-	cat_into_file("0", TRACEDIR "/tracing_on");
-	cat_into_file("\n", TRACEDIR "/trace");
-	if (1) {
-		cat_into_file("function_graph", TRACEDIR "/current_tracer");
-		cat_into_file("1", TRACEDIR "/options/funcgraph-proc");
-	} else {
-		cat_into_file("nop", TRACEDIR "/current_tracer");
-	}
-	cat_into_file(pidstr, TRACEDIR "/set_ftrace_pid");
-	cat_into_file("1", TRACEDIR "/tracing_on");
-	dprintf1("enabled tracing\n");
-#endif
-}
-
-static void tracing_off(void)
-{
-#if CONTROL_TRACING > 0
-	if (!tracing_root_ok())
-		return;
-	cat_into_file("0", "/sys/kernel/tracing/tracing_on");
-#endif
-}
-
-void abort_hooks(void)
-{
-	fflush(stdout);
-	fprintf(stderr, "running %s()...\n", __func__);
-	tracing_off();
-#ifdef SLEEP_ON_ABORT
-	sleep(SLEEP_ON_ABORT);
-#endif
-}
-
 /*
  * This attempts to have roughly a page of instructions followed by a few
  * instructions that do a write, and another page of instructions.  That
-- 
2.25.1

[PATCH v10 2/6] selftests/mm: unify pkey sighandler selftest assertions and tracing

[Hongfu Li]

Add per-test tracing to the pkey signal-handler selftest and use
pkey_assert() for error handling. Each test enables tracing at start
and disables it at end; on failure, pkey_assert() calls abort_hooks()
to turn tracing off so ftrace is not left enabled.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Tested-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 .../selftests/mm/pkey_sighandler_tests.c      | 89 +++++++++----------
 1 file changed, 44 insertions(+), 45 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index 302fef54049c..8b3400379423 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -19,7 +19,6 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <signal.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <sys/types.h>
@@ -207,15 +206,14 @@ static void test_sigsegv_handler_with_pkey0_disabled(void)
 	struct sigaction sa;
 	pthread_attr_t attr;
 	pthread_t thr;
+	int ret;
 
 	sa.sa_flags = SA_SIGINFO;
 
 	sa.sa_sigaction = sigsegv_handler;
 	sigemptyset(&sa.sa_mask);
-	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGSEGV, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	memset(&siginfo, 0, sizeof(siginfo));
 
@@ -247,15 +245,14 @@ static void test_sigsegv_handler_cannot_access_stack(void)
 	struct sigaction sa;
 	pthread_attr_t attr;
 	pthread_t thr;
+	int ret;
 
 	sa.sa_flags = SA_SIGINFO;
 
 	sa.sa_sigaction = sigsegv_handler;
 	sigemptyset(&sa.sa_mask);
-	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGSEGV, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	memset(&siginfo, 0, sizeof(siginfo));
 
@@ -288,21 +285,20 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
+	long ret;
 
 	sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
 
 	sa.sa_sigaction = sigsegv_handler;
 
 	sigemptyset(&sa.sa_mask);
-	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGSEGV, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	stack = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE,
 		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
-	assert(stack != MAP_FAILED);
+	pkey_assert(stack != MAP_FAILED);
 
 	/* Allow access to MPK 0 and MPK 1 */
 	pkey_reg = pkey_reg_restrictive_default();
@@ -323,13 +319,13 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 	memset(&siginfo, 0, sizeof(siginfo));
 
 	/* Use clone to avoid newer glibcs using rseq on new threads */
-	long ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
-			     CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			     CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
-			     CLONE_DETACHED,
-			     stack + STACK_SIZE,
-			     &parent_pid,
-			     &child_pid);
+	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
+			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
+			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
+			CLONE_DETACHED,
+			stack + STACK_SIZE,
+			&parent_pid,
+			&child_pid);
 
 	if (ret < 0) {
 		errno = -ret;
@@ -358,6 +354,7 @@ static void test_pkru_preserved_after_sigusr1(void)
 {
 	struct sigaction sa;
 	u64 pkey_reg;
+	int ret;
 
 	/* Allow access to MPK 0 and an arbitrary set of keys */
 	pkey_reg = pkey_reg_restrictive_default();
@@ -369,10 +366,8 @@ static void test_pkru_preserved_after_sigusr1(void)
 
 	sa.sa_sigaction = sigusr1_handler;
 	sigemptyset(&sa.sa_mask);
-	if (sigaction(SIGUSR1, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGUSR1, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	memset(&siginfo, 0, sizeof(siginfo));
 
@@ -444,6 +439,13 @@ static void test_pkru_sigreturn(void)
 	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
+	long ret;
+
+	/*
+	 * SIGSEGV handler is reset to SIG_DFL below; turn tracing off first
+	 * so a crash does not leave ftrace enabled.
+	 */
+	tracing_off();
 
 	sa.sa_handler = SIG_DFL;
 	sa.sa_flags = 0;
@@ -453,24 +455,20 @@ static void test_pkru_sigreturn(void)
 	 * For this testcase, we do not want to handle SIGSEGV. Reset handler
 	 * to default so that the application can crash if it receives SIGSEGV.
 	 */
-	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGSEGV, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
 	sa.sa_sigaction = sigusr2_handler;
 	sigemptyset(&sa.sa_mask);
 
-	if (sigaction(SIGUSR2, &sa, NULL) == -1) {
-		perror("sigaction");
-		exit(EXIT_FAILURE);
-	}
+	ret = sigaction(SIGUSR2, &sa, NULL);
+	pkey_assert(ret == 0);
 
 	stack = mmap(0, STACK_SIZE, PROT_READ | PROT_WRITE,
 		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
-	assert(stack != MAP_FAILED);
+	pkey_assert(stack != MAP_FAILED);
 
 	/*
 	 * Allow access to MPK 0 and MPK 2. The child thread (to be created
@@ -494,13 +492,13 @@ static void test_pkru_sigreturn(void)
 	sigstack.ss_size = STACK_SIZE;
 
 	/* Use clone to avoid newer glibcs using rseq on new threads */
-	long ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
-			     CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			     CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
-			     CLONE_DETACHED,
-			     stack + STACK_SIZE,
-			     &parent_pid,
-			     &child_pid);
+	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
+			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
+			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
+			CLONE_DETACHED,
+			stack + STACK_SIZE,
+			&parent_pid,
+			&child_pid);
 
 	if (ret < 0) {
 		errno = -ret;
@@ -530,16 +528,17 @@ static void (*pkey_tests[])(void) = {
 
 int main(int argc, char *argv[])
 {
-	int i;
-
 	ksft_print_header();
 	ksft_set_plan(ARRAY_SIZE(pkey_tests));
 
 	if (!is_pkeys_supported())
 		ksft_exit_skip("pkeys not supported\n");
 
-	for (i = 0; i < ARRAY_SIZE(pkey_tests); i++)
-		(*pkey_tests[i])();
+	for (test_nr = 0; test_nr < ARRAY_SIZE(pkey_tests); test_nr++) {
+		tracing_on();
+		(*pkey_tests[test_nr])();
+		tracing_off();
+	}
 
 	ksft_finished();
 	return 0;
-- 
2.25.1

[PATCH v10 3/6] selftests/mm: use pkey_assert on clone_raw failure in pkey test

[Hongfu Li]

Use pkey_assert(0) instead of perror("clone") when clone_raw() fails.
The old path only printed an error and continued; the test now exits
via pkey_assert() on failure so it does not hang or proceed with an
invalid child.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Tested-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 tools/testing/selftests/mm/pkey_sighandler_tests.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index 8b3400379423..188513e94fc5 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -329,7 +329,7 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 
 	if (ret < 0) {
 		errno = -ret;
-		perror("clone");
+		pkey_assert(0);
 	} else if (ret == 0) {
 		thread_segv_maperr_ptr(&sigstack);
 		syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
@@ -502,7 +502,7 @@ static void test_pkru_sigreturn(void)
 
 	if (ret < 0) {
 		errno = -ret;
-		perror("clone");
+		pkey_assert(0);
 	}  else if (ret == 0) {
 		thread_sigusr2_self(&sigstack);
 		syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
-- 
2.25.1

[PATCH v10 4/6] selftests/mm: add missing mmap() return checks in pkey tests

[Hongfu Li]

Add missing checks against mmap() return value, replace (void *)-1
with MAP_FAILED for better readability and consistency.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Tested-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 tools/testing/selftests/mm/pkey-powerpc.h          |  2 +-
 tools/testing/selftests/mm/pkey_sighandler_tests.c |  2 ++
 tools/testing/selftests/mm/protection_keys.c       | 12 +++++++-----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey-powerpc.h b/tools/testing/selftests/mm/pkey-powerpc.h
index 17bf2d1b0192..2ce85580b404 100644
--- a/tools/testing/selftests/mm/pkey-powerpc.h
+++ b/tools/testing/selftests/mm/pkey-powerpc.h
@@ -126,7 +126,7 @@ static inline void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 p
 			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 = syscall(__NR_subpage_prot, ptr, size, NULL);
 	if (ret) {
diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index 188513e94fc5..8f98e6d9349f 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -313,6 +313,7 @@ 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);
+	pkey_assert(sigstack.ss_sp != MAP_FAILED);
 	sigstack.ss_flags = 0;
 	sigstack.ss_size = STACK_SIZE;
 
@@ -488,6 +489,7 @@ 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);
+	pkey_assert(sigstack.ss_sp != MAP_FAILED);
 	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 be4a0470cc61..ae6e1530b354 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -582,7 +582,7 @@ 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);
@@ -605,7 +605,7 @@ 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);
 
@@ -663,7 +663,7 @@ 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);
@@ -692,7 +692,7 @@ static void *malloc_pkey(long size, int prot, u16 pkey)
 		pkey_assert(malloc_type < nr_malloc_types);
 
 		ret = pkey_malloc[malloc_type](size, prot, pkey);
-		pkey_assert(ret != (void *)-1);
+		pkey_assert(ret != MAP_FAILED);
 
 		malloc_type++;
 		if (malloc_type >= nr_malloc_types)
@@ -1110,6 +1110,7 @@ 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 */
 
@@ -1676,7 +1677,8 @@ int main(void)
 		ksft_print_msg("running PKEY tests for unsupported CPU/OS\n");
 
 		ptr  = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
-		assert(ptr != (void *)-1);
+		if (ptr == MAP_FAILED)
+			ksft_exit_fail_perror("mmap");
 		test_mprotect_pkey_on_unsupported_cpu(ptr, 1);
 		ksft_test_result_pass("pkey on unsupported CPU/OS\n");
 		ksft_finished();
-- 
2.25.1

[PATCH v10 5/6] selftests/mm: add missing pthread_create() return checks in pkey tests

[Hongfu Li]

Add missing pthread_create() return checks in pkey sighandler tests
to avoid hanging in pthread_cond_wait() when thread creation fails.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Tested-by: Kevin Brodsky <kevin.brodsky@arm.com>
---
 tools/testing/selftests/mm/pkey_sighandler_tests.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index 8f98e6d9349f..cbc24d6cf770 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -220,7 +220,11 @@ static void test_sigsegv_handler_with_pkey0_disabled(void)
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 
-	pthread_create(&thr, &attr, thread_segv_with_pkey0_disabled, NULL);
+	ret = pthread_create(&thr, &attr, thread_segv_with_pkey0_disabled, NULL);
+	if (ret) {
+		errno = ret;
+		pkey_assert(0);
+	}
 
 	pthread_mutex_lock(&mutex);
 	while (siginfo.si_signo == 0)
@@ -259,7 +263,11 @@ static void test_sigsegv_handler_cannot_access_stack(void)
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 
-	pthread_create(&thr, &attr, thread_segv_pkuerr_stack, NULL);
+	ret = pthread_create(&thr, &attr, thread_segv_pkuerr_stack, NULL);
+	if (ret) {
+		errno = ret;
+		pkey_assert(0);
+	}
 
 	pthread_mutex_lock(&mutex);
 	while (siginfo.si_signo == 0)
-- 
2.25.1

[PATCH v10 6/6] selftests/mm: fix clone cleartid race in pkey sighandler tests

[Hongfu Li]

Passing a stack-local child_pid to clone() with CLONE_CHILD_CLEARTID is
unsafe: the kernel clears that address when the child exits, which may
happen after the test function has returned and the stack slot has been
reused.

Neither testcase uses the settid/cleartid pointers for synchronization.

Drop CLONE_PARENT_SETTID and CLONE_CHILD_CLEARTID and pass NULL for the
clone tid arguments. Wait for the clone child to exit via tkill in
test_sigsegv_handler_with_different_pkey_for_stack(), matching
test_pkru_sigreturn(), so the detached thread cannot overlap with the
next testcase.

Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
---
 .../selftests/mm/pkey_sighandler_tests.c      | 20 +++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
index cbc24d6cf770..c218d0510a2a 100644
--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
+++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -290,7 +290,6 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 	static stack_t sigstack;
 	void *stack;
 	int pkey;
-	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
 	long ret;
@@ -330,11 +329,10 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 	/* Use clone to avoid newer glibcs using rseq on new threads */
 	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
 			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
 			CLONE_DETACHED,
 			stack + STACK_SIZE,
-			&parent_pid,
-			&child_pid);
+			NULL,
+			NULL);
 
 	if (ret < 0) {
 		errno = -ret;
@@ -344,11 +342,19 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void)
 		syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
 	}
 
+	child_pid = ret;
+
 	pthread_mutex_lock(&mutex);
 	while (siginfo.si_signo == 0)
 		pthread_cond_wait(&cond, &mutex);
 	pthread_mutex_unlock(&mutex);
 
+	/* Wait for child to exit before returning */
+	do {
+		sched_yield();
+		ret = syscall_raw(SYS_tkill, child_pid, 0, 0, 0, 0, 0);
+	} while (ret != -ESRCH && ret != -EINVAL);
+
 	ksft_test_result(siginfo.si_signo == SIGSEGV &&
 			 siginfo.si_code == SEGV_MAPERR &&
 			 siginfo.si_addr == NULL,
@@ -445,7 +451,6 @@ static void test_pkru_sigreturn(void)
 	static stack_t sigstack;
 	void *stack;
 	int pkey;
-	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
 	long ret;
@@ -504,11 +509,10 @@ static void test_pkru_sigreturn(void)
 	/* Use clone to avoid newer glibcs using rseq on new threads */
 	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
 			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
 			CLONE_DETACHED,
 			stack + STACK_SIZE,
-			&parent_pid,
-			&child_pid);
+			NULL,
+			NULL);
 
 	if (ret < 0) {
 		errno = -ret;
-- 
2.25.1

Re: [PATCH v10 0/6] selftests/mm: refactor pkey helpers and fix mmap error handling

[Andrew Morton]

On Mon,  6 Jul 2026 16:15:54 +0800 Hongfu Li <lihongfu@kylinos.cn> wrote:

> The main changes in this series are to refactor shared tracing and assertion
> helpers into a common file, unify both pkey selftests on pkey_assert() and
> per-test tracing for consistent diagnostics, and add missing mmap() return
> checks with MAP_FAILED used throughout for readability and consistency.

Thanks, I've updated mm.git to this version.

> v10:
> - Add patch 6/6 to fix a pre-existing cleartid race: remove unused
>   settid/cleartid clone flags and wait for the clone child to exit in
>   the sigsegv test.

Below is how v10 altered mm.git.  As you mentioned, this is all from
the addition of [patch 6/6].

btw, I thought the official way to wait for a child thread to exit is
pthread_join()?  Why is that sched_yield() loop used?


 tools/testing/selftests/mm/pkey_sighandler_tests.c |   20 ++++++-----
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/tools/testing/selftests/mm/pkey_sighandler_tests.c~b
+++ a/tools/testing/selftests/mm/pkey_sighandler_tests.c
@@ -290,7 +290,6 @@ static void test_sigsegv_handler_with_di
 	static stack_t sigstack;
 	void *stack;
 	int pkey;
-	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
 	long ret;
@@ -330,11 +329,10 @@ static void test_sigsegv_handler_with_di
 	/* Use clone to avoid newer glibcs using rseq on new threads */
 	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
 			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
 			CLONE_DETACHED,
 			stack + STACK_SIZE,
-			&parent_pid,
-			&child_pid);
+			NULL,
+			NULL);
 
 	if (ret < 0) {
 		errno = -ret;
@@ -344,11 +342,19 @@ static void test_sigsegv_handler_with_di
 		syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0);
 	}
 
+	child_pid = ret;
+
 	pthread_mutex_lock(&mutex);
 	while (siginfo.si_signo == 0)
 		pthread_cond_wait(&cond, &mutex);
 	pthread_mutex_unlock(&mutex);
 
+	/* Wait for child to exit before returning */
+	do {
+		sched_yield();
+		ret = syscall_raw(SYS_tkill, child_pid, 0, 0, 0, 0, 0);
+	} while (ret != -ESRCH && ret != -EINVAL);
+
 	ksft_test_result(siginfo.si_signo == SIGSEGV &&
 			 siginfo.si_code == SEGV_MAPERR &&
 			 siginfo.si_addr == NULL,
@@ -445,7 +451,6 @@ static void test_pkru_sigreturn(void)
 	static stack_t sigstack;
 	void *stack;
 	int pkey;
-	int parent_pid = 0;
 	int child_pid = 0;
 	u64 pkey_reg;
 	long ret;
@@ -504,11 +509,10 @@ static void test_pkru_sigreturn(void)
 	/* Use clone to avoid newer glibcs using rseq on new threads */
 	ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES |
 			CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
-			CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
 			CLONE_DETACHED,
 			stack + STACK_SIZE,
-			&parent_pid,
-			&child_pid);
+			NULL,
+			NULL);
 
 	if (ret < 0) {
 		errno = -ret;
_

Re: [PATCH v10 0/6] selftests/mm: refactor pkey helpers and fix mmap error handling

[Hongfu Li]

Hi,

> > The main changes in this series are to refactor shared tracing and assertion
> > helpers into a common file, unify both pkey selftests on pkey_assert() and
> > per-test tracing for consistent diagnostics, and add missing mmap() return
> > checks with MAP_FAILED used throughout for readability and consistency.
> 
> Thanks, I've updated mm.git to this version.
> 
> > v10:
> > - Add patch 6/6 to fix a pre-existing cleartid race: remove unused
> >   settid/cleartid clone flags and wait for the clone child to exit in
> >   the sigsegv test.
> 
> Below is how v10 altered mm.git.  As you mentioned, this is all from
> the addition of [patch 6/6].
> 
> btw, I thought the official way to wait for a child thread to exit is
> pthread_join()?  Why is that sched_yield() loop used?

Thanks a lot for your question.

As I understand it, the primary reason is pthread_create automatically
enables rseq on all threads, which corrupts the isolated pkey signal
handling kernel context this selftest is designed to exercise. We use
raw clone_raw explicitly to avoid rseq interference as noted in the
code comment.

Besides, pthread_join cannot work here. Since the thread is created via
raw clone instead of pthread_create, it is not tracked by libpthread at
all, so invoking pthread_join with its TID will return EINVAL.

Best regards,
Hongfu