selftests/futex: Add futex_numa_mpol

Test the basic functionality for the NUMA and MPOL flags:
- FUTEX2_NUMA should take the NUMA node which is after the uaddr
and use it.
- Only update the node if FUTEX_NO_NODE was set by the user
- FUTEX2_MPOL should use the memory based on the policy. I attempted to
set the node with mbind() and then use this with MPOL but this fails
and futex falls back to the default node for the current CPU.

Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/futex/functional/.gitignore

···
 # SPDX-License-Identifier: GPL-2.0-only
+futex_numa_mpol
 futex_priv_hash
 futex_requeue
 futex_requeue_pi

tools/testing/selftests/futex/functional/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
 CFLAGS := $(CFLAGS) -g -O2 -Wall -pthread $(INCLUDES) $(KHDR_INCLUDES)
-LDLIBS := -lpthread -lrt
+LDLIBS := -lpthread -lrt -lnuma
 
 LOCAL_HDRS := \
 	../include/futextest.h \
···
 	futex_wait \
 	futex_requeue \
 	futex_priv_hash \
+	futex_numa_mpol \
 	futex_waitv
 
 TEST_PROGS := run.sh

tools/testing/selftests/futex/functional/futex_numa_mpol.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2025 Sebastian Andrzej Siewior <[e-mail]>
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <numa.h>
+#include <numaif.h>
+
+#include <linux/futex.h>
+#include <sys/mman.h>
+
+#include "logging.h"
+#include "futextest.h"
+#include "futex2test.h"
+
+#define MAX_THREADS	64
+
+static pthread_barrier_t barrier_main;
+static pthread_t threads[MAX_THREADS];
+
+struct thread_args {
+	void *futex_ptr;
+	unsigned int flags;
+	int result;
+};
+
+static struct thread_args thread_args[MAX_THREADS];
+
+#ifndef FUTEX_NO_NODE
+#define FUTEX_NO_NODE (-1)
+#endif
+
+#ifndef FUTEX2_MPOL
+#define FUTEX2_MPOL	0x08
+#endif
+
+static void *thread_lock_fn(void *arg)
+{
+	struct thread_args *args = arg;
+	int ret;
+
+	pthread_barrier_wait(&barrier_main);
+	ret = futex2_wait(args->futex_ptr, 0, args->flags, NULL, 0);
+	args->result = ret;
+	return NULL;
+}
+
+static void create_max_threads(void *futex_ptr)
+{
+	int i, ret;
+
+	for (i = 0; i < MAX_THREADS; i++) {
+		thread_args[i].futex_ptr = futex_ptr;
+		thread_args[i].flags = FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA;
+		thread_args[i].result = 0;
+		ret = pthread_create(&threads[i], NULL, thread_lock_fn, &thread_args[i]);
+		if (ret) {
+			error("pthread_create failed\n", errno);
+			exit(1);
+		}
+	}
+}
+
+static void join_max_threads(void)
+{
+	int i, ret;
+
+	for (i = 0; i < MAX_THREADS; i++) {
+		ret = pthread_join(threads[i], NULL);
+		if (ret) {
+			error("pthread_join failed for thread %d\n", errno, i);
+			exit(1);
+		}
+	}
+}
+
+static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flags)
+{
+	int to_wake, ret, i, need_exit = 0;
+
+	pthread_barrier_init(&barrier_main, NULL, MAX_THREADS + 1);
+	create_max_threads(futex_ptr);
+	pthread_barrier_wait(&barrier_main);
+	to_wake = MAX_THREADS;
+
+	do {
+		ret = futex2_wake(futex_ptr, to_wake, futex_flags);
+		if (must_fail) {
+			if (ret < 0)
+				break;
+			fail("Should fail, but didn't\n");
+			exit(1);
+		}
+		if (ret < 0) {
+			error("Failed futex2_wake(%d)\n", errno, to_wake);
+			exit(1);
+		}
+		if (!ret)
+			usleep(50);
+		to_wake -= ret;
+
+	} while (to_wake);
+	join_max_threads();
+
+	for (i = 0; i < MAX_THREADS; i++) {
+		if (must_fail && thread_args[i].result != -1) {
+			fail("Thread %d should fail but succeeded (%d)\n", i, thread_args[i].result);
+			need_exit = 1;
+		}
+		if (!must_fail && thread_args[i].result != 0) {
+			fail("Thread %d failed (%d)\n", i, thread_args[i].result);
+			need_exit = 1;
+		}
+	}
+	if (need_exit)
+		exit(1);
+}
+
+static void test_futex(void *futex_ptr, int must_fail)
+{
+	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
+}
+
+static void test_futex_mpol(void *futex_ptr, int must_fail)
+{
+	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
+}
+
+static void usage(char *prog)
+{
+	printf("Usage: %s\n", prog);
+	printf("  -c    Use color\n");
+	printf("  -h    Display this help message\n");
+	printf("  -v L  Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
+	       VQUIET, VCRITICAL, VINFO);
+}
+
+int main(int argc, char *argv[])
+{
+	struct futex32_numa *futex_numa;
+	int mem_size, i;
+	void *futex_ptr;
+	char c;
+
+	while ((c = getopt(argc, argv, "chv:")) != -1) {
+		switch (c) {
+		case 'c':
+			log_color(1);
+			break;
+		case 'h':
+			usage(basename(argv[0]));
+			exit(0);
+			break;
+		case 'v':
+			log_verbosity(atoi(optarg));
+			break;
+		default:
+			usage(basename(argv[0]));
+			exit(1);
+		}
+	}
+
+	mem_size = sysconf(_SC_PAGE_SIZE);
+	futex_ptr = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+	if (futex_ptr == MAP_FAILED) {
+		error("mmap() for %d bytes failed\n", errno, mem_size);
+		return 1;
+	}
+	futex_numa = futex_ptr;
+
+	info("Regular test\n");
+	futex_numa->futex = 0;
+	futex_numa->numa = FUTEX_NO_NODE;
+	test_futex(futex_ptr, 0);
+
+	if (futex_numa->numa == FUTEX_NO_NODE) {
+		fail("NUMA node is left unitiliazed\n");
+		return 1;
+	}
+
+	info("Memory too small\n");
+	test_futex(futex_ptr + mem_size - 4, 1);
+
+	info("Memory out of range\n");
+	test_futex(futex_ptr + mem_size, 1);
+
+	futex_numa->numa = FUTEX_NO_NODE;
+	mprotect(futex_ptr, mem_size, PROT_READ);
+	info("Memory, RO\n");
+	test_futex(futex_ptr, 1);
+
+	mprotect(futex_ptr, mem_size, PROT_NONE);
+	info("Memory, no access\n");
+	test_futex(futex_ptr, 1);
+
+	mprotect(futex_ptr, mem_size, PROT_READ | PROT_WRITE);
+	info("Memory back to RW\n");
+	test_futex(futex_ptr, 0);
+
+	/* MPOL test. Does not work as expected */
+	for (i = 0; i < 4; i++) {
+		unsigned long nodemask;
+		int ret;
+
+		nodemask = 1 << i;
+		ret = mbind(futex_ptr, mem_size, MPOL_BIND, &nodemask,
+			    sizeof(nodemask) * 8, 0);
+		if (ret == 0) {
+			info("Node %d test\n", i);
+			futex_numa->futex = 0;
+			futex_numa->numa = FUTEX_NO_NODE;
+
+			ret = futex2_wake(futex_ptr, 0, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
+			if (ret < 0)
+				error("Failed to wake 0 with MPOL.\n", errno);
+			if (0)
+				test_futex_mpol(futex_numa, 0);
+			if (futex_numa->numa != i) {
+				fail("Returned NUMA node is %d expected %d\n",
+				     futex_numa->numa, i);
+			}
+		}
+	}
+	return 0;
+}

tools/testing/selftests/futex/functional/run.sh

···
 echo
 ./futex_priv_hash $COLOR
 ./futex_priv_hash -g $COLOR
+
+echo
+./futex_numa_mpol $COLOR

tools/testing/selftests/futex/include/futex2test.h

···
 };
 #endif
 
+#ifndef __NR_futex_wake
+#define __NR_futex_wake 454
+#endif
+
+#ifndef __NR_futex_wait
+#define __NR_futex_wait 455
+#endif
+
 #ifndef FUTEX2_SIZE_U32
 #define FUTEX2_SIZE_U32 0x02
+#endif
+
+#ifndef FUTEX2_NUMA
+#define FUTEX2_NUMA 0x04
+#endif
+
+#ifndef FUTEX2_MPOL
+#define FUTEX2_MPOL 0x08
+#endif
+
+#ifndef FUTEX2_PRIVATE
+#define FUTEX2_PRIVATE FUTEX_PRIVATE_FLAG
+#endif
+
+#ifndef FUTEX2_NO_NODE
+#define FUTEX_NO_NODE (-1)
 #endif
 
 #ifndef FUTEX_32
 #define FUTEX_32 FUTEX2_SIZE_U32
 #endif
+
+struct futex32_numa {
+	futex_t futex;
+	futex_t numa;
+};
 
 /**
  * futex_waitv - Wait at multiple futexes, wake on any
···
 			      unsigned long flags, struct timespec *timo, clockid_t clockid)
 {
 	return syscall(__NR_futex_waitv, waiters, nr_waiters, flags, timo, clockid);
+}
+
+/*
+ * futex_wait() - block on uaddr with optional timeout
+ * @val:	Expected value
+ * @flags:	FUTEX2 flags
+ * @timeout:	Relative timeout
+ * @clockid:	Clock id for the timeout
+ */
+static inline int futex2_wait(void *uaddr, long val, unsigned int flags,
+			      struct timespec *timeout, clockid_t clockid)
+{
+	return syscall(__NR_futex_wait, uaddr, val, ~0U, flags, timeout, clockid);
+}
+
+/*
+ * futex2_wake() - Wake a number of futexes
+ * @nr:		Number of threads to wake at most
+ * @flags:	FUTEX2 flags
+ */
+static inline int futex2_wake(void *uaddr, int nr, unsigned int flags)
+{
+	return syscall(__NR_futex_wake, uaddr, ~0U, nr, flags);
 }