1 files changed, 117 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
new file mode 100644
index 000000000000..f9ac20c657ec
--- /dev/null
+++ b/tools/testing/selftests/mm/hugetlb_dio.c
@@ -0,0 +1,117 @@
+// 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();
+}