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Message-ID: <20250702142052.45116-1-usama.anjum@collabora.com>
Date: Wed, 2 Jul 2025 19:20:51 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Shuah Khan <shuah@...nel.org>
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>,
kernel@...labora.com,
David Hildenbrand <david@...hat.com>,
linux-mm@...ck.org,
linux-kselftest@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2] selftests/mm: pagemap_scan ioctl: add PFN ZERO test cases
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 <david@...hat.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
---
The bug has been fixed [1].
[1] https://lore.kernel.org/all/20250617143532.2375383-1-david@redhat.com
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;
+}
+
+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");
+
+ ret = madvise(mem, mem_size, MADV_HUGEPAGE);
+ if (!ret) {
+ for (i = 0; i < mem_size; i += hpage_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 huge pages must have PFNZERO set\n", __func__);
+
+ free(mem);
+ } else {
+ ksft_test_result_skip("%s huge page not supported\n", __func__);
+ }
+}
+
int main(int __attribute__((unused)) argc, char *argv[])
{
int shmid, buf_size, fd, i, ret;
@@ -1494,7 +1575,7 @@ int main(int __attribute__((unused)) argc, char *argv[])
if (init_uffd())
ksft_exit_pass();
- ksft_set_plan(115);
+ ksft_set_plan(117);
page_size = getpagesize();
hpage_size = read_pmd_pagesize();
@@ -1669,6 +1750,9 @@ int main(int __attribute__((unused)) argc, char *argv[])
/* 16. Userfaultfd tests */
userfaultfd_tests();
+ /* 17. ZEROPFN tests */
+ zeropfn_tests();
+
close(pagemap_fd);
ksft_exit_pass();
}
--
2.43.0
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