selftests/mm: move uffd pagemap test to unit test

Move it over and make it split into two tests, one for pagemap and one for
the new WP_UNPOPULATED (to be a separate one).

The thp pagemap test wasn't really working (with MADV_HUGEPAGE).  Let's
just drop it (since it never really worked anyway..) and leave that for
later.

Link: https://lkml.kernel.org/r/20230412164352.328733-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
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: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

@@ -670,157 +670,6 @@ static int userfaultfd_minor_test(void)
 	return args.missing_faults != 0 || args.minor_faults != nr_pages;
 }
 
-static int pagemap_open(void)
-{
-	int fd = open("/proc/self/pagemap", O_RDONLY);
-
-	if (fd < 0)
-		err("open pagemap");
-
-	return fd;
-}
-
-/* This macro let __LINE__ works in err() */
-#define  pagemap_check_wp(value, wp) do {				\
-		if (!!(value & PM_UFFD_WP) != wp)			\
-			err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \
-	} while (0)
-
-static int pagemap_test_fork(bool present)
-{
-	pid_t child = fork();
-	uint64_t value;
-	int fd, result;
-
-	if (!child) {
-		/* Open the pagemap fd of the child itself */
-		fd = pagemap_open();
-		value = pagemap_get_entry(fd, area_dst);
-		/*
-		 * After fork() uffd-wp bit should be gone as long as we're
-		 * without UFFD_FEATURE_EVENT_FORK
-		 */
-		pagemap_check_wp(value, false);
-		/* Succeed */
-		exit(0);
-	}
-	waitpid(child, &result, 0);
-	return result;
-}
-
-static void userfaultfd_wp_unpopulated_test(int pagemap_fd)
-{
-	uint64_t value;
-
-	/* Test applying pte marker to anon unpopulated */
-	wp_range(uffd, (uint64_t)area_dst, page_size, true);
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, true);
-
-	/* Test unprotect on anon pte marker */
-	wp_range(uffd, (uint64_t)area_dst, page_size, false);
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, false);
-
-	/* Test zap on anon marker */
-	wp_range(uffd, (uint64_t)area_dst, page_size, true);
-	if (madvise(area_dst, page_size, MADV_DONTNEED))
-		err("madvise(MADV_DONTNEED) failed");
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, false);
-
-	/* Test fault in after marker removed */
-	*area_dst = 1;
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, false);
-	/* Drop it to make pte none again */
-	if (madvise(area_dst, page_size, MADV_DONTNEED))
-		err("madvise(MADV_DONTNEED) failed");
-
-	/* Test read-zero-page upon pte marker */
-	wp_range(uffd, (uint64_t)area_dst, page_size, true);
-	*(volatile char *)area_dst;
-	/* Drop it to make pte none again */
-	if (madvise(area_dst, page_size, MADV_DONTNEED))
-		err("madvise(MADV_DONTNEED) failed");
-}
-
-static void userfaultfd_pagemap_test(unsigned int test_pgsize)
-{
-	int pagemap_fd;
-	uint64_t value;
-
-	/* Pagemap tests uffd-wp only */
-	if (!test_uffdio_wp)
-		return;
-
-	/* Not enough memory to test this page size */
-	if (test_pgsize > nr_pages * page_size)
-		return;
-
-	printf("testing uffd-wp with pagemap (pgsize=%u): ", test_pgsize);
-	/* Flush so it doesn't flush twice in parent/child later */
-	fflush(stdout);
-
-	uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED);
-
-	if (test_pgsize > page_size) {
-		/* This is a thp test */
-		if (madvise(area_dst, nr_pages * page_size, MADV_HUGEPAGE))
-			err("madvise(MADV_HUGEPAGE) failed");
-	} else if (test_pgsize == page_size) {
-		/* This is normal page test; force no thp */
-		if (madvise(area_dst, nr_pages * page_size, MADV_NOHUGEPAGE))
-			err("madvise(MADV_NOHUGEPAGE) failed");
-	}
-
-	if (uffd_register(uffd, area_dst, nr_pages * page_size,
-			  false, true, false))
-		err("register failed");
-
-	pagemap_fd = pagemap_open();
-
-	/* Smoke test WP_UNPOPULATED first when it's still empty */
-	if (test_pgsize == page_size)
-		userfaultfd_wp_unpopulated_test(pagemap_fd);
-
-	/* Touch the page */
-	*area_dst = 1;
-	wp_range(uffd, (uint64_t)area_dst, test_pgsize, true);
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, true);
-	/* Make sure uffd-wp bit dropped when fork */
-	if (pagemap_test_fork(true))
-		err("Detected stall uffd-wp bit in child");
-
-	/* Exclusive required or PAGEOUT won't work */
-	if (!(value & PM_MMAP_EXCLUSIVE))
-		err("multiple mapping detected: 0x%"PRIx64, value);
-
-	if (madvise(area_dst, test_pgsize, MADV_PAGEOUT))
-		err("madvise(MADV_PAGEOUT) failed");
-
-	/* Uffd-wp should persist even swapped out */
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, true);
-	/* Make sure uffd-wp bit dropped when fork */
-	if (pagemap_test_fork(false))
-		err("Detected stall uffd-wp bit in child");
-
-	/* Unprotect; this tests swap pte modifications */
-	wp_range(uffd, (uint64_t)area_dst, page_size, false);
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, false);
-
-	/* Fault in the page from disk */
-	*area_dst = 2;
-	value = pagemap_get_entry(pagemap_fd, area_dst);
-	pagemap_check_wp(value, false);
-
-	close(pagemap_fd);
-	printf("done\n");
-}
-
 static int userfaultfd_stress(void)
 {
 	void *area;
@@ -932,21 +781,6 @@ static int userfaultfd_stress(void)
 		uffd_stats_report(args, nr_cpus);
 	}
 
-	if (test_type == TEST_ANON) {
-		/*
-		 * shmem/hugetlb won't be able to run since they have different
-		 * behavior on fork() (file-backed memory normally drops ptes
-		 * directly when fork), meanwhile the pagemap test will verify
-		 * pgtable entry of fork()ed child.
-		 */
-		userfaultfd_pagemap_test(page_size);
-		/*
-		 * Hard-code for x86_64 for now for 2M THP, as x86_64 is
-		 * currently the only one that supports uffd-wp
-		 */
-		userfaultfd_pagemap_test(page_size * 512);
-	}
-
 	return userfaultfd_zeropage_test() || userfaultfd_sig_test()
 		|| userfaultfd_events_test() || userfaultfd_minor_test();
 }

tools/testing/selftests/mm/uffd-unit-tests.c

@@ -197,7 +197,152 @@ static bool uffd_feature_supported(uffd_test_case_t *test)
 	    test->uffd_feature_required;
 }
 
+static int pagemap_open(void)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+
+	if (fd < 0)
+		err("open pagemap");
+
+	return fd;
+}
+
+/* This macro let __LINE__ works in err() */
+#define  pagemap_check_wp(value, wp) do {				\
+		if (!!(value & PM_UFFD_WP) != wp)			\
+			err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \
+	} while (0)
+
+static int pagemap_test_fork(bool present)
+{
+	pid_t child = fork();
+	uint64_t value;
+	int fd, result;
+
+	if (!child) {
+		/* Open the pagemap fd of the child itself */
+		fd = pagemap_open();
+		value = pagemap_get_entry(fd, area_dst);
+		/*
+		 * After fork() uffd-wp bit should be gone as long as we're
+		 * without UFFD_FEATURE_EVENT_FORK
+		 */
+		pagemap_check_wp(value, false);
+		/* Succeed */
+		exit(0);
+	}
+	waitpid(child, &result, 0);
+	return result;
+}
+
+static void uffd_wp_unpopulated_test(void)
+{
+	uint64_t value;
+	int pagemap_fd;
+
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  false, true, false))
+		err("register failed");
+
+	pagemap_fd = pagemap_open();
+
+	/* Test applying pte marker to anon unpopulated */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+
+	/* Test unprotect on anon pte marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, false);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Test zap on anon marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Test fault in after marker removed */
+	*area_dst = 1;
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+	/* Drop it to make pte none again */
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+
+	/* Test read-zero-page upon pte marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	*(volatile char *)area_dst;
+	/* Drop it to make pte none again */
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+
+	uffd_test_pass();
+}
+
+static void uffd_pagemap_test(void)
+{
+	int pagemap_fd;
+	uint64_t value;
+
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  false, true, false))
+		err("register failed");
+
+	pagemap_fd = pagemap_open();
+
+	/* Touch the page */
+	*area_dst = 1;
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+	/* Make sure uffd-wp bit dropped when fork */
+	if (pagemap_test_fork(true))
+		err("Detected stall uffd-wp bit in child");
+
+	/* Exclusive required or PAGEOUT won't work */
+	if (!(value & PM_MMAP_EXCLUSIVE))
+		err("multiple mapping detected: 0x%"PRIx64, value);
+
+	if (madvise(area_dst, page_size, MADV_PAGEOUT))
+		err("madvise(MADV_PAGEOUT) failed");
+
+	/* Uffd-wp should persist even swapped out */
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+	/* Make sure uffd-wp bit dropped when fork */
+	if (pagemap_test_fork(false))
+		err("Detected stall uffd-wp bit in child");
+
+	/* Unprotect; this tests swap pte modifications */
+	wp_range(uffd, (uint64_t)area_dst, page_size, false);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Fault in the page from disk */
+	*area_dst = 2;
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	close(pagemap_fd);
+	uffd_test_pass();
+}
+
 uffd_test_case_t uffd_tests[] = {
+	{
+		.name = "pagemap",
+		.uffd_fn = uffd_pagemap_test,
+		.mem_targets = MEM_ANON,
+		.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP,
+	},
+	{
+		.name = "wp-unpopulated",
+		.uffd_fn = uffd_wp_unpopulated_test,
+		.mem_targets = MEM_ANON,
+		.uffd_feature_required =
+		UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_UNPOPULATED,
+	},
 };
 
 int main(int argc, char *argv[])