[PATCH 22/29] selftests/mm: Move uffd pagemap test to unit test

Peter Xu
2023-03-30T16:14:27Z

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.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
tools/testing/selftests/mm/uffd-stress.c | 166 -------------------
tools/testing/selftests/mm/uffd-unit-tests.c | 145 ++++++++++++++++
2 files changed, 145 insertions(+), 166 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
index 70cb0619354e..50738a993afc 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -671,157 +671,6 @@ static int userfaultfd_minor_test(void)
return stats.missing_faults != 0 || stats.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;
@@ -933,21 +782,6 @@ static int userfaultfd_stress(void)
uffd_stats_report(uffd_stats, 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();
}
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 007145063363..bcd67bd4ec90 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -200,7 +200,152 @@ 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[])
--
2.39.1