2 files changed, 119 insertions(+)
create mode 100644 tools/testing/selftests/mm/hugetlb_dio.c
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 3b49bc3d0a3b..a1748a4c7df1 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -73,6 +73,7 @@ TEST_GEN_FILES += ksm_functional_tests
TEST_GEN_FILES += mdwe_test
TEST_GEN_FILES += hugetlb_fault_after_madv
TEST_GEN_FILES += hugetlb_madv_vs_map
+TEST_GEN_FILES += hugetlb_dio
ifneq ($(ARCH),arm64)
TEST_GEN_FILES += soft-dirty
diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
new file mode 100644
index 000000000000..986f3b6c7f7b
--- /dev/null
+++ b/tools/testing/selftests/mm/hugetlb_dio.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This program tests for hugepage leaks after DIO writes to a file using a
+ * hugepage as the user buffer. During DIO, the user buffer is pinned and
+ * should be properly unpinned upon completion. This patch verifies that the
+ * kernel correctly unpins the buffer at DIO completion for both aligned and
+ * unaligned user buffer offsets (w.r.t page boundary), ensuring the hugepage
+ * is freed upon unmapping.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/mman.h>
+#include "vm_util.h"
+#include "../kselftest.h"
+
+void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off)
+{
+ int fd;
+ char *buffer = NULL;
+ char *orig_buffer = NULL;
+ size_t h_pagesize = 0;
+ size_t writesize;
+ int free_hpage_b = 0;
+ int free_hpage_a = 0;
+ const int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;
+ const int mmap_prot = PROT_READ | PROT_WRITE;
+
+ writesize = end_off - start_off;
+
+ /* Get the default huge page size */
+ h_pagesize = default_huge_page_size();
+ if (!h_pagesize)
+ ksft_exit_fail_msg("Unable to determine huge page size\n");
+
+ /* Open the file to DIO */
+ fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
+ if (fd < 0)
+ ksft_exit_fail_perror("Error opening file\n");
+
+ /* Get the free huge pages before allocation */
+ free_hpage_b = get_free_hugepages();
+ if (free_hpage_b == 0) {
+ close(fd);
+ ksft_exit_skip("No free hugepage, exiting!\n");
+ }
+
+ /* Allocate a hugetlb page */
+ orig_buffer = mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0);
+ if (orig_buffer == MAP_FAILED) {
+ close(fd);
+ ksft_exit_fail_perror("Error mapping memory\n");
+ }
+ buffer = orig_buffer;
+ buffer += start_off;
+
+ memset(buffer, 'A', writesize);
+
+ /* Write the buffer to the file */
+ if (write(fd, buffer, writesize) != (writesize)) {
+ munmap(orig_buffer, h_pagesize);
+ close(fd);
+ ksft_exit_fail_perror("Error writing to file\n");
+ }
+
+ /* unmap the huge page */
+ munmap(orig_buffer, h_pagesize);
+ close(fd);
+
+ /* Get the free huge pages after unmap*/
+ free_hpage_a = get_free_hugepages();
+
+ /*
+ * If the no. of free hugepages before allocation and after unmap does
+ * not match - that means there could still be a page which is pinned.
+ */
+ if (free_hpage_a != free_hpage_b) {
+ ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b);
+ ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a);
+ ksft_test_result_fail(": Huge pages not freed!\n");
+ } else {
+ ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b);
+ ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a);
+ ksft_test_result_pass(": Huge pages freed successfully !\n");
+ }
+}
+
+int main(void)
+{
+ size_t pagesize = 0;
+
+ ksft_print_header();
+ ksft_set_plan(4);
+
+ /* Get base page size */
+ pagesize = psize();
+
+ /* start and end is aligned to pagesize */
+ run_dio_using_hugetlb(0, (pagesize * 3));
+
+ /* start is aligned but end is not aligned */
+ run_dio_using_hugetlb(0, (pagesize * 3) - (pagesize / 2));
+
+ /* start is unaligned and end is aligned */
+ run_dio_using_hugetlb(pagesize / 2, (pagesize * 3));
+
+ /* both start and end are unaligned */
+ run_dio_using_hugetlb(pagesize / 2, (pagesize * 3) + (pagesize / 2));
+
+ ksft_finished();
+}
+
