On 02.07.25 16:20, Muhammad Usama Anjum wrote:
Add test cases to test the correctness of PFN ZERO flag of pagemap_scan
ioctl. Test with normal pages backed memory and huge pages backed
memory.
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Muhammad Usama Anjum <[email protected]>
---
The bug has been fixed [1].
[1] https://lore.kernel.org/all/[email protected]
Changes since v1:
- Skip if madvise() fails
- Skip test if use_zero_page isn't set to 1
- Keep on using memalign()+free() to allocate huge pages
---
tools/testing/selftests/mm/pagemap_ioctl.c | 86 +++++++++++++++++++++-
1 file changed, 85 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/mm/pagemap_ioctl.c
b/tools/testing/selftests/mm/pagemap_ioctl.c
index 57b4bba2b45f3..976ab357f4651 100644
--- a/tools/testing/selftests/mm/pagemap_ioctl.c
+++ b/tools/testing/selftests/mm/pagemap_ioctl.c
@@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
+
#define _GNU_SOURCE
#include <stdio.h>
#include <fcntl.h>
@@ -1480,6 +1481,86 @@ static void transact_test(int page_size)
extra_thread_faults);
}
+bool is_use_zero_page_set(void)
+{
+ ssize_t bytes_read;
+ char buffer[2];
+ int fd;
+
+ fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
O_RDONLY);
+ if (fd < 0)
+ return 0;
+
+ bytes_read = read(fd, buffer, sizeof(buffer) - 1);
+ if (bytes_read <= 0) {
+ close(fd);
+ return 0;
+ }
+
+ close(fd);
+ if (atoi(buffer) != 1)
+ return 0;
+
+ return 1;
+}
You should probably factor out detect_huge_zeropage() from cow.c into
vm_utils.c, and let it return the result.
+
+void zeropfn_tests(void)
+{
+ unsigned long long mem_size;
+ struct page_region vec;
+ int i, ret;
+ char *mem;
+
+ /* Test with normal memory */
+ mem_size = 10 * page_size;
+ mem = mmap(NULL, mem_size, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
+ if (mem == MAP_FAILED)
+ ksft_exit_fail_msg("error nomem\n");
+
+ /* Touch each page to ensure it's mapped */
+ for (i = 0; i < mem_size; i += page_size)
+ (void)((volatile char *)mem)[i];
+
+ ret = pagemap_ioctl(mem, mem_size, &vec, 1, 0,
+ (mem_size / page_size), PAGE_IS_PFNZERO, 0, 0,
PAGE_IS_PFNZERO);
+ if (ret < 0)
+ ksft_exit_fail_msg("error %d %d %s\n", ret, errno,
strerror(errno));
+
+ ksft_test_result(ret == 1 && LEN(vec) == (mem_size / page_size),
+ "%s all pages must have PFNZERO set\n", __func__);
+
+ munmap(mem, mem_size);
+
+ /* Test with huge page if user_zero_page is set to 1 */
+ if (!is_use_zero_page_set()) {
+ ksft_test_result_skip("%s use_zero_page not supported or set to
1\n", __func__);
+ return;
+ }
+
+ mem_size = 10 * hpage_size;
+ mem = memalign(hpage_size, mem_size);
+ if (!mem)
+ ksft_exit_fail_msg("error nomem\n");
Didn't we discuss using mmap() instead?
See run_with_huge_zeropage() in cow.c on how to do the alignemnt
yourself easily.
--
Cheers,
David / dhildenb
