selftests/mm: allow allocate_area() to fail properly

Mostly to detect hugetlb allocation errors and skip hugetlb tests when
pages are not allocated.

Link: https://lkml.kernel.org/r/20230412164345.328659-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/uffd-common.c

@@ -44,10 +44,15 @@ static void anon_release_pages(char *rel_area)
 		err("madvise(MADV_DONTNEED) failed");
 }
 
-static void anon_allocate_area(void **alloc_area, bool is_src)
+static int anon_allocate_area(void **alloc_area, bool is_src)
 {
 	*alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
 			   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
+	return 0;
 }
 
 static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
@@ -65,7 +70,7 @@ static void hugetlb_release_pages(char *rel_area)
 	}
 }
 
-static void hugetlb_allocate_area(void **alloc_area, bool is_src)
+static int hugetlb_allocate_area(void **alloc_area, bool is_src)
 {
 	off_t size = nr_pages * page_size;
 	off_t offset = is_src ? 0 : size;
@@ -77,14 +82,16 @@ static void hugetlb_allocate_area(void **alloc_area, bool is_src)
 			   (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 (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
 
 	if (map_shared) {
 		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");
+			return -errno;
 	}
 
 	if (is_src) {
@@ -96,6 +103,7 @@ static void hugetlb_allocate_area(void **alloc_area, bool is_src)
 		*alloc_area_alias = area_alias;
 
 	close(mem_fd);
+	return 0;
 }
 
 static void hugetlb_alias_mapping(__u64 *start, size_t len, unsigned long offset)
@@ -112,7 +120,7 @@ static void shmem_release_pages(char *rel_area)
 		err("madvise(MADV_REMOVE) failed");
 }
 
-static void shmem_allocate_area(void **alloc_area, bool is_src)
+static int shmem_allocate_area(void **alloc_area, bool is_src)
 {
 	void *area_alias = NULL;
 	size_t bytes = nr_pages * page_size, hpage_size = read_pmd_pagesize();
@@ -132,15 +140,20 @@ static void shmem_allocate_area(void **alloc_area, bool is_src)
 
 	*alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
 			   mem_fd, offset);
-	if (*alloc_area == MAP_FAILED)
-		err("mmap of memfd failed");
+	if (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
 	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,
 			  mem_fd, offset);
-	if (area_alias == MAP_FAILED)
-		err("mmap of memfd alias failed");
+	if (area_alias == MAP_FAILED) {
+		munmap(*alloc_area, bytes);
+		*alloc_area = NULL;
+		return -errno;
+	}
 	if (test_collapse && area_alias != p_alias)
 		err("mmap of anonymous memory failed at %p", p_alias);
 
@@ -150,6 +163,7 @@ static void shmem_allocate_area(void **alloc_area, bool is_src)
 		area_dst_alias = area_alias;
 
 	close(mem_fd);
+	return 0;
 }
 
 static void shmem_alias_mapping(__u64 *start, size_t len, unsigned long offset)
@@ -282,14 +296,19 @@ static void uffd_test_ctx_clear(void)
 	munmap_area((void **)&area_remap);
 }
 
-void uffd_test_ctx_init(uint64_t features)
+int uffd_test_ctx_init(uint64_t features)
 {
 	unsigned long nr, cpu;
+	int ret;
 
 	uffd_test_ctx_clear();
 
-	uffd_test_ops->allocate_area((void **)&area_src, true);
-	uffd_test_ops->allocate_area((void **)&area_dst, false);
+	ret = uffd_test_ops->allocate_area((void **)&area_src, true);
+	if (ret)
+		return ret;
+	ret = uffd_test_ops->allocate_area((void **)&area_dst, false);
+	if (ret)
+		return ret;
 
 	userfaultfd_open(&features);
 
@@ -337,6 +356,8 @@ void uffd_test_ctx_init(uint64_t features)
 	for (cpu = 0; cpu < nr_cpus; cpu++)
 		if (pipe2(&pipefd[cpu * 2], O_CLOEXEC | O_NONBLOCK))
 			err("pipe");
+
+	return 0;
 }
 
 void wp_range(int ufd, __u64 start, __u64 len, bool wp)

tools/testing/selftests/mm/uffd-common.h

@@ -80,7 +80,7 @@ struct uffd_args {
 };
 
 struct uffd_test_ops {
-	void (*allocate_area)(void **alloc_area, bool is_src);
+	int (*allocate_area)(void **alloc_area, bool is_src);
 	void (*release_pages)(char *rel_area);
 	void (*alias_mapping)(__u64 *start, size_t len, unsigned long offset);
 	void (*check_pmd_mapping)(void *p, int expect_nr_hpages);
@@ -101,7 +101,7 @@ extern uffd_test_ops_t hugetlb_uffd_test_ops;
 extern uffd_test_ops_t *uffd_test_ops;
 
 void uffd_stats_report(struct uffd_args *args, int n_cpus);
-void uffd_test_ctx_init(uint64_t features);
+int uffd_test_ctx_init(uint64_t features);
 void userfaultfd_open(uint64_t *features);
 int uffd_read_msg(int ufd, struct uffd_msg *msg);
 void wp_range(int ufd, __u64 start, __u64 len, bool wp);