Merge: selftests/mm: hugetlb_fault_after_madv: use default hugetlb page size

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6588

JIRA: https://issues.redhat.com/browse/RHEL-60023
Tested: Ran the test on s390x and x86-64, with the expected output.

Let's make the test also work as expected on architectures that have
a different hugepage size than 2 MiB -- such as s390x. While at it,
backport the test output cleanup part of the same upstream series.

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

Approved-by: Rafael Aquini <raquini@redhat.com>
Approved-by: mcasquer <mcasquer@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

tools/testing/selftests/mm/hugetlb_fault_after_madv.c

@@ -5,20 +5,36 @@
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <setjmp.h>
+#include <signal.h>
 
 #include "vm_util.h"
 #include "../kselftest.h"
 
-#define MMAP_SIZE (1 << 21)
 #define INLOOP_ITER 100
 
-char *huge_ptr;
+static char *huge_ptr;
+static size_t huge_page_size;
+
+static sigjmp_buf sigbuf;
+static bool sigbus_triggered;
+
+static void signal_handler(int signal)
+{
+	if (signal == SIGBUS) {
+		sigbus_triggered = true;
+		siglongjmp(sigbuf, 1);
+	}
+}
 
 /* Touch the memory while it is being madvised() */
 void *touch(void *unused)
 {
 	char *ptr = (char *)huge_ptr;
 
+	if (sigsetjmp(sigbuf, 1))
+		return NULL;
+
 	for (int i = 0; i < INLOOP_ITER; i++)
 		ptr[0] = '.';
 
@@ -30,7 +46,7 @@ void *madv(void *unused)
 	usleep(rand() % 10);
 
 	for (int i = 0; i < INLOOP_ITER; i++)
-		madvise(huge_ptr, MMAP_SIZE, MADV_DONTNEED);
+		madvise(huge_ptr, huge_page_size, MADV_DONTNEED);
 
 	return NULL;
 }
@@ -44,17 +60,31 @@ int main(void)
 	 * interactions
 	 */
 	int max = 10000;
+	int err;
+
+	ksft_print_header();
+	ksft_set_plan(1);
 
 	srand(getpid());
 
+	if (signal(SIGBUS, signal_handler) == SIG_ERR)
+		ksft_exit_skip("Could not register signal handler.");
+
+	huge_page_size = default_huge_page_size();
+	if (!huge_page_size)
+		ksft_exit_skip("Could not detect default hugetlb page size.");
+
+	ksft_print_msg("[INFO] detected default hugetlb page size: %zu KiB\n",
+		       huge_page_size / 1024);
+
 	free_hugepages = get_free_hugepages();
 	if (free_hugepages != 1) {
 		ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",
 			       free_hugepages);
 	}
 
 	while (max--) {
-		huge_ptr = mmap(NULL, MMAP_SIZE, PROT_READ | PROT_WRITE,
+		huge_ptr = mmap(NULL, huge_page_size, PROT_READ | PROT_WRITE,
 				MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
 				-1, 0);
 
@@ -66,8 +96,14 @@ int main(void)
 
 		pthread_join(thread1, NULL);
 		pthread_join(thread2, NULL);
-		munmap(huge_ptr, MMAP_SIZE);
+		munmap(huge_ptr, huge_page_size);
 	}
 
-	return KSFT_PASS;
+	ksft_test_result(!sigbus_triggered, "SIGBUS behavior\n");
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	ksft_exit_pass();
 }