selftests/vm: use memfd for uffd hugetlb tests

Patch series "selftests/vm: Drop hugetlb mntpoint in run_vmtests.sh", v2.

Clean the code up so we can use the same memfd for both hugetlb and shmem
which is cleaner.


This patch (of 4):

We already used memfd for shmem test, move it forward with hugetlb too so
that we don't need user to specify the hugetlb file path explicitly when
running hugetlb shared tests.

Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Peter Xu <[e-mail]>
Reviewed-by: Axel Rasmussen <[e-mail]>
Cc: Axel Rasmussen <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/vm/userfaultfd.c

···
 static bool test_uffdio_wp = true;
 /* Whether to test uffd minor faults */
 static bool test_uffdio_minor = false;
-
 static bool map_shared;
-static int shm_fd;
-static int huge_fd;
+static int mem_fd;
 static unsigned long long *count_verify;
 static int uffd = -1;
 static int uffd_flags, finished, *pipefd;
···
     "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
     "./userfaultfd hugetlb 256 50\n\n"
     "# Run the same hugetlb test but using shared file:\n"
-    "./userfaultfd hugetlb_shared 256 50 /dev/hugepages/hugefile\n\n"
+    "./userfaultfd hugetlb_shared 256 50\n\n"
     "# 10MiB-~6GiB 999 bounces anonymous test, "
     "continue forever unless an error triggers\n"
     "while ./userfaultfd anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";
···
 
 static void hugetlb_allocate_area(void **alloc_area, bool is_src)
 {
+	off_t size = nr_pages * page_size;
+	off_t offset = is_src ? 0 : size;
 	void *area_alias = NULL;
 	char **alloc_area_alias;
 
-	if (!map_shared)
-		*alloc_area = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB |
-				(is_src ? 0 : MAP_NORESERVE),
-			-1,
-			0);
-	else
-		*alloc_area = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_SHARED |
-				(is_src ? 0 : MAP_NORESERVE),
-			huge_fd,
-			is_src ? 0 : nr_pages * page_size);
+	*alloc_area = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   (map_shared ? MAP_SHARED : MAP_PRIVATE) |
+			   (is_src ? 0 : MAP_NORESERVE),
+			   mem_fd, offset);
 	if (*alloc_area == MAP_FAILED)
 		err("mmap of hugetlbfs file failed");
 
 	if (map_shared) {
-		area_alias = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_SHARED,
-			huge_fd,
-			is_src ? 0 : nr_pages * page_size);
+		area_alias = mmap(NULL, size, PROT_READ | PROT_WRITE,
+				  MAP_SHARED, mem_fd, offset);
 		if (area_alias == MAP_FAILED)
 			err("mmap of hugetlb file alias failed");
 	}
···
 	}
 
 	*alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
-			   shm_fd, offset);
+			   mem_fd, offset);
 	if (*alloc_area == MAP_FAILED)
 		err("mmap of memfd failed");
 	if (test_collapse && *alloc_area != p)
 		err("mmap of memfd failed at %p", p);
 
 	area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
-			  shm_fd, offset);
+			  mem_fd, offset);
 	if (area_alias == MAP_FAILED)
 		err("mmap of memfd alias failed");
 	if (test_collapse && area_alias != p_alias)
···
 	}
 	nr_pages = nr_pages_per_cpu * nr_cpus;
 
-	if (test_type == TEST_HUGETLB && map_shared) {
-		if (argc < 5)
-			usage();
-		huge_fd = open(argv[4], O_CREAT | O_RDWR, 0755);
-		if (huge_fd < 0)
-			err("Open of %s failed", argv[4]);
-		if (ftruncate(huge_fd, 0))
-			err("ftruncate %s to size 0 failed", argv[4]);
-	} else if (test_type == TEST_SHMEM) {
-		shm_fd = memfd_create(argv[0], 0);
-		if (shm_fd < 0)
+	if (test_type == TEST_SHMEM || test_type == TEST_HUGETLB) {
+		unsigned int memfd_flags = 0;
+
+		if (test_type == TEST_HUGETLB)
+			memfd_flags = MFD_HUGETLB;
+		mem_fd = memfd_create(argv[0], memfd_flags);
+		if (mem_fd < 0)
 			err("memfd_create");
-		if (ftruncate(shm_fd, nr_pages * page_size * 2))
+		if (ftruncate(mem_fd, nr_pages * page_size * 2))
 			err("ftruncate");
-		if (fallocate(shm_fd,
+		if (fallocate(mem_fd,
 			      FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,
 			      nr_pages * page_size * 2))
 			err("fallocate");