[PATCH v3 2/2] selftests/mm: Smoke test WP_UNPOPULATED

From: Peter Xu
Date: Mon Mar 06 2023 - 16:40:29 EST


Enable it by default on the stress test, and add some smoke tests for the
pte markers on anonymous.

Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
tools/testing/selftests/mm/userfaultfd.c | 45 ++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
index 7f22844ed704..e030d63c031a 100644
--- a/tools/testing/selftests/mm/userfaultfd.c
+++ b/tools/testing/selftests/mm/userfaultfd.c
@@ -1444,6 +1444,43 @@ static int pagemap_test_fork(bool present)
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_read_vaddr(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_read_vaddr(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_read_vaddr(pagemap_fd, area_dst);
+ pagemap_check_wp(value, false);
+
+ /* Test fault in after marker removed */
+ *area_dst = 1;
+ value = pagemap_read_vaddr(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)
{
struct uffdio_register uffdio_register;
@@ -1462,7 +1499,7 @@ static void userfaultfd_pagemap_test(unsigned int test_pgsize)
/* Flush so it doesn't flush twice in parent/child later */
fflush(stdout);

- uffd_test_ctx_init(0);
+ uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED);

if (test_pgsize > page_size) {
/* This is a thp test */
@@ -1482,6 +1519,10 @@ static void userfaultfd_pagemap_test(unsigned int test_pgsize)

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);
@@ -1526,7 +1567,7 @@ static int userfaultfd_stress(void)
struct uffdio_register uffdio_register;
struct uffd_stats uffd_stats[nr_cpus];

- uffd_test_ctx_init(0);
+ uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED);

if (posix_memalign(&area, page_size, page_size))
err("out of memory");
--
2.39.1