[RFC PATCH v2 43/47] selftests/vm: add HugeTLB HGM to userfaultfd selftest

From: James Houghton
Date: Fri Oct 21 2022 - 12:41:08 EST


This test case behaves similarly to the regular shared HugeTLB
configuration, except that it uses 4K instead of hugepages, and that we
ignore the UFFDIO_COPY tests, as UFFDIO_CONTINUE is the only ioctl that
supports PAGE_SIZE-aligned regions.

This doesn't test MADV_COLLAPSE. Other tests are added later to exercise
MADV_COLLAPSE.

Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
tools/testing/selftests/vm/userfaultfd.c | 90 +++++++++++++++++++-----
1 file changed, 74 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 7f22844ed704..c9cdfb20f292 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -73,9 +73,10 @@ static unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size, hpage_size;
#define BOUNCE_POLL (1<<3)
static int bounces;

-#define TEST_ANON 1
-#define TEST_HUGETLB 2
-#define TEST_SHMEM 3
+#define TEST_ANON 1
+#define TEST_HUGETLB 2
+#define TEST_HUGETLB_HGM 3
+#define TEST_SHMEM 4
static int test_type;

#define UFFD_FLAGS (O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY)
@@ -93,6 +94,8 @@ static volatile bool test_uffdio_zeropage_eexist = true;
static bool test_uffdio_wp = true;
/* Whether to test uffd minor faults */
static bool test_uffdio_minor = false;
+static bool test_uffdio_copy = true;
+
static bool map_shared;
static int mem_fd;
static unsigned long long *count_verify;
@@ -151,7 +154,7 @@ static void usage(void)
fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces> "
"[hugetlbfs_file]\n\n");
fprintf(stderr, "Supported <test type>: anon, hugetlb, "
- "hugetlb_shared, shmem\n\n");
+ "hugetlb_shared, hugetlb_shared_hgm, shmem\n\n");
fprintf(stderr, "'Test mods' can be joined to the test type string with a ':'. "
"Supported mods:\n");
fprintf(stderr, "\tsyscall - Use userfaultfd(2) (default)\n");
@@ -167,6 +170,11 @@ static void usage(void)
exit(1);
}

+static bool test_is_hugetlb(void)
+{
+ return test_type == TEST_HUGETLB || test_type == TEST_HUGETLB_HGM;
+}
+
#define _err(fmt, ...) \
do { \
int ret = errno; \
@@ -381,8 +389,12 @@ static struct uffd_test_ops *uffd_test_ops;

static inline uint64_t uffd_minor_feature(void)
{
- if (test_type == TEST_HUGETLB && map_shared)
- return UFFD_FEATURE_MINOR_HUGETLBFS;
+ if (test_is_hugetlb() && map_shared)
+ return UFFD_FEATURE_MINOR_HUGETLBFS |
+ (test_type == TEST_HUGETLB_HGM
+ ? (UFFD_FEATURE_MINOR_HUGETLBFS_HGM |
+ UFFD_FEATURE_EXACT_ADDRESS)
+ : 0);
else if (test_type == TEST_SHMEM)
return UFFD_FEATURE_MINOR_SHMEM;
else
@@ -393,7 +405,7 @@ static uint64_t get_expected_ioctls(uint64_t mode)
{
uint64_t ioctls = UFFD_API_RANGE_IOCTLS;

- if (test_type == TEST_HUGETLB)
+ if (test_is_hugetlb())
ioctls &= ~(1 << _UFFDIO_ZEROPAGE);

if (!((mode & UFFDIO_REGISTER_MODE_WP) && test_uffdio_wp))
@@ -500,13 +512,16 @@ static void uffd_test_ctx_clear(void)
static void uffd_test_ctx_init(uint64_t features)
{
unsigned long nr, cpu;
+ uint64_t enabled_features = features;

uffd_test_ctx_clear();

uffd_test_ops->allocate_area((void **)&area_src, true);
uffd_test_ops->allocate_area((void **)&area_dst, false);

- userfaultfd_open(&features);
+ userfaultfd_open(&enabled_features);
+ if ((enabled_features & features) != features)
+ err("couldn't enable all features");

count_verify = malloc(nr_pages * sizeof(unsigned long long));
if (!count_verify)
@@ -726,13 +741,21 @@ static void uffd_handle_page_fault(struct uffd_msg *msg,
struct uffd_stats *stats)
{
unsigned long offset;
+ unsigned long address;

if (msg->event != UFFD_EVENT_PAGEFAULT)
err("unexpected msg event %u", msg->event);

+ /*
+ * Round down address to nearest page_size.
+ * We do this manually because we specified UFFD_FEATURE_EXACT_ADDRESS
+ * to support UFFD_FEATURE_MINOR_HUGETLBFS_HGM.
+ */
+ address = msg->arg.pagefault.address & ~(page_size - 1);
+
if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP) {
/* Write protect page faults */
- wp_range(uffd, msg->arg.pagefault.address, page_size, false);
+ wp_range(uffd, address, page_size, false);
stats->wp_faults++;
} else if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_MINOR) {
uint8_t *area;
@@ -751,11 +774,10 @@ static void uffd_handle_page_fault(struct uffd_msg *msg,
*/

area = (uint8_t *)(area_dst +
- ((char *)msg->arg.pagefault.address -
- area_dst_alias));
+ ((char *)address - area_dst_alias));
for (b = 0; b < page_size; ++b)
area[b] = ~area[b];
- continue_range(uffd, msg->arg.pagefault.address, page_size);
+ continue_range(uffd, address, page_size);
stats->minor_faults++;
} else {
/*
@@ -782,7 +804,7 @@ static void uffd_handle_page_fault(struct uffd_msg *msg,
if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
err("unexpected write fault");

- offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
+ offset = (char *)address - area_dst;
offset &= ~(page_size-1);

if (copy_page(uffd, offset))
@@ -1192,6 +1214,12 @@ static int userfaultfd_events_test(void)
char c;
struct uffd_stats stats = { 0 };

+ if (!test_uffdio_copy) {
+ printf("Skipping userfaultfd events test "
+ "(test_uffdio_copy=false)\n");
+ return 0;
+ }
+
printf("testing events (fork, remap, remove): ");
fflush(stdout);

@@ -1245,6 +1273,12 @@ static int userfaultfd_sig_test(void)
char c;
struct uffd_stats stats = { 0 };

+ if (!test_uffdio_copy) {
+ printf("Skipping userfaultfd signal test "
+ "(test_uffdio_copy=false)\n");
+ return 0;
+ }
+
printf("testing signal delivery: ");
fflush(stdout);

@@ -1538,6 +1572,12 @@ static int userfaultfd_stress(void)
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, 16*1024*1024);

+ if (!test_uffdio_copy) {
+ printf("Skipping userfaultfd stress test "
+ "(test_uffdio_copy=false)\n");
+ bounces = 0;
+ }
+
while (bounces--) {
printf("bounces: %d, mode:", bounces);
if (bounces & BOUNCE_RANDOM)
@@ -1696,6 +1736,16 @@ static void set_test_type(const char *type)
uffd_test_ops = &hugetlb_uffd_test_ops;
/* Minor faults require shared hugetlb; only enable here. */
test_uffdio_minor = true;
+ } else if (!strcmp(type, "hugetlb_shared_hgm")) {
+ map_shared = true;
+ test_type = TEST_HUGETLB_HGM;
+ uffd_test_ops = &hugetlb_uffd_test_ops;
+ /*
+ * HugeTLB HGM only changes UFFDIO_CONTINUE, so don't test
+ * UFFDIO_COPY.
+ */
+ test_uffdio_minor = true;
+ test_uffdio_copy = false;
} else if (!strcmp(type, "shmem")) {
map_shared = true;
test_type = TEST_SHMEM;
@@ -1731,6 +1781,7 @@ static void parse_test_type_arg(const char *raw_type)
err("Unsupported test: %s", raw_type);

if (test_type == TEST_HUGETLB)
+ /* TEST_HUGETLB_HGM gets small pages. */
page_size = hpage_size;
else
page_size = sysconf(_SC_PAGE_SIZE);
@@ -1813,22 +1864,29 @@ int main(int argc, char **argv)
nr_cpus = x < y ? x : y;
}
nr_pages_per_cpu = bytes / page_size / nr_cpus;
+ if (test_type == TEST_HUGETLB_HGM)
+ /*
+ * `page_size` refers to the page_size we can use in
+ * UFFDIO_CONTINUE. We still need nr_pages to be appropriately
+ * aligned, so align it here.
+ */
+ nr_pages_per_cpu -= nr_pages_per_cpu % (hpage_size / page_size);
if (!nr_pages_per_cpu) {
_err("invalid MiB");
usage();
}
+ nr_pages = nr_pages_per_cpu * nr_cpus;

bounces = atoi(argv[3]);
if (bounces <= 0) {
_err("invalid bounces");
usage();
}
- nr_pages = nr_pages_per_cpu * nr_cpus;

- if (test_type == TEST_SHMEM || test_type == TEST_HUGETLB) {
+ if (test_type == TEST_SHMEM || test_is_hugetlb()) {
unsigned int memfd_flags = 0;

- if (test_type == TEST_HUGETLB)
+ if (test_is_hugetlb())
memfd_flags = MFD_HUGETLB;
mem_fd = memfd_create(argv[0], memfd_flags);
if (mem_fd < 0)
--
2.38.0.135.g90850a2211-goog