1 files changed, 154 insertions, 28 deletions

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index d3c7f5fb3e7b..aa7400ed0e99 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -5,6 +5,7 @@
  */
 
 #define _GNU_SOURCE
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
@@ -14,6 +15,7 @@
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/mount.h>
+#include <sys/param.h>
 #include <malloc.h>
 #include <stdbool.h>
 #include <time.h>
@@ -84,7 +86,67 @@ static void write_debugfs(const char *fmt, ...)
 	write_file(SPLIT_DEBUGFS, input, ret + 1);
 }
 
-void split_pmd_thp(void)
+static char *allocate_zero_filled_hugepage(size_t len)
+{
+	char *result;
+	size_t i;
+
+	result = memalign(pmd_pagesize, len);
+	if (!result) {
+		printf("Fail to allocate memory\n");
+		exit(EXIT_FAILURE);
+	}
+
+	madvise(result, len, MADV_HUGEPAGE);
+
+	for (i = 0; i < len; i++)
+		result[i] = (char)0;
+
+	return result;
+}
+
+static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len)
+{
+	unsigned long rss_anon_before, rss_anon_after;
+	size_t i;
+
+	if (!check_huge_anon(one_page, 4, pmd_pagesize))
+		ksft_exit_fail_msg("No THP is allocated\n");
+
+	rss_anon_before = rss_anon();
+	if (!rss_anon_before)
+		ksft_exit_fail_msg("No RssAnon is allocated before split\n");
+
+	/* split all THPs */
+	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
+		      (uint64_t)one_page + len, 0);
+
+	for (i = 0; i < len; i++)
+		if (one_page[i] != (char)0)
+			ksft_exit_fail_msg("%ld byte corrupted\n", i);
+
+	if (!check_huge_anon(one_page, 0, pmd_pagesize))
+		ksft_exit_fail_msg("Still AnonHugePages not split\n");
+
+	rss_anon_after = rss_anon();
+	if (rss_anon_after >= rss_anon_before)
+		ksft_exit_fail_msg("Incorrect RssAnon value. Before: %ld After: %ld\n",
+		       rss_anon_before, rss_anon_after);
+}
+
+void split_pmd_zero_pages(void)
+{
+	char *one_page;
+	int nr_hpages = 4;
+	size_t len = nr_hpages * pmd_pagesize;
+
+	one_page = allocate_zero_filled_hugepage(len);
+	verify_rss_anon_split_huge_page_all_zeroes(one_page, nr_hpages, len);
+	ksft_test_result_pass("Split zero filled huge pages successful\n");
+	free(one_page);
+}
+
+void split_pmd_thp_to_order(int order)
 {
 	char *one_page;
 	size_t len = 4 * pmd_pagesize;
@@ -104,7 +166,7 @@ void split_pmd_thp(void)
 
 	/* split all THPs */
 	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
-		(uint64_t)one_page + len, 0);
+		(uint64_t)one_page + len, order);
 
 	for (i = 0; i < len; i++)
 		if (one_page[i] != (char)i)
@@ -114,7 +176,7 @@ void split_pmd_thp(void)
 	if (!check_huge_anon(one_page, 0, pmd_pagesize))
 		ksft_exit_fail_msg("Still AnonHugePages not split\n");
 
-	ksft_test_result_pass("Split huge pages successful\n");
+	ksft_test_result_pass("Split huge pages to order %d successful\n", order);
 	free(one_page);
 }
 
@@ -201,18 +263,32 @@ void split_pte_mapped_thp(void)
 	close(kpageflags_fd);
 }
 
-void split_file_backed_thp(void)
+void split_file_backed_thp(int order)
 {
 	int status;
 	int fd;
-	ssize_t num_written;
 	char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
 	const char *tmpfs_loc = mkdtemp(tmpfs_template);
 	char testfile[INPUT_MAX];
+	ssize_t num_written, num_read;
+	char *file_buf1, *file_buf2;
 	uint64_t pgoff_start = 0, pgoff_end = 1024;
+	int i;
 
 	ksft_print_msg("Please enable pr_debug in split_huge_pages_in_file() for more info.\n");
 
+	file_buf1 = (char *)malloc(pmd_pagesize);
+	file_buf2 = (char *)malloc(pmd_pagesize);
+
+	if (!file_buf1 || !file_buf2) {
+		ksft_print_msg("cannot allocate file buffers\n");
+		goto out;
+	}
+
+	for (i = 0; i < pmd_pagesize; i++)
+		file_buf1[i] = (char)i;
+	memset(file_buf2, 0, pmd_pagesize);
+
 	status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");
 
 	if (status)
@@ -221,26 +297,45 @@ void split_file_backed_thp(void)
 	status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
 	if (status >= INPUT_MAX) {
 		ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n");
+		goto cleanup;
 	}
 
-	fd = open(testfile, O_CREAT|O_WRONLY, 0664);
+	fd = open(testfile, O_CREAT|O_RDWR, 0664);
 	if (fd == -1) {
 		ksft_perror("Cannot open testing file");
 		goto cleanup;
 	}
 
-	/* write something to the file, so a file-backed THP can be allocated */
-	num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1);
-	close(fd);
+	/* write pmd size data to the file, so a file-backed THP can be allocated */
+	num_written = write(fd, file_buf1, pmd_pagesize);
 
-	if (num_written < 1) {
-		ksft_perror("Fail to write data to testing file");
-		goto cleanup;
+	if (num_written == -1 || num_written != pmd_pagesize) {
+		ksft_perror("Failed to write data to testing file");
+		goto close_file;
 	}
 
 	/* split the file-backed THP */
-	write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, 0);
+	write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, order);
 
+	/* check file content after split */
+	status = lseek(fd, 0, SEEK_SET);
+	if (status == -1) {
+		ksft_perror("Cannot lseek file");
+		goto close_file;
+	}
+
+	num_read = read(fd, file_buf2, num_written);
+	if (num_read == -1 || num_read != num_written) {
+		ksft_perror("Cannot read file content back");
+		goto close_file;
+	}
+
+	if (strncmp(file_buf1, file_buf2, pmd_pagesize) != 0) {
+		ksft_print_msg("File content changed\n");
+		goto close_file;
+	}
+
+	close(fd);
 	status = unlink(testfile);
 	if (status) {
 		ksft_perror("Cannot remove testing file");
@@ -258,12 +353,15 @@ void split_file_backed_thp(void)
 		ksft_exit_fail_msg("cannot remove tmp dir: %s\n", strerror(errno));
 
 	ksft_print_msg("Please check dmesg for more information\n");
-	ksft_test_result_pass("File-backed THP split test done\n");
+	ksft_test_result_pass("File-backed THP split to order %d test done\n", order);
 	return;
 
+close_file:
+	close(fd);
 cleanup:
 	umount(tmpfs_loc);
 	rmdir(tmpfs_loc);
+out:
 	ksft_exit_fail_msg("Error occurred\n");
 }
 
@@ -300,7 +398,8 @@ int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd,
 		char **addr)
 {
 	size_t i;
-	int __attribute__((unused)) dummy = 0;
+	int dummy = 0;
+	unsigned char buf[1024];
 
 	srand(time(NULL));
 
@@ -308,11 +407,12 @@ int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd,
 	if (*fd == -1)
 		ksft_exit_fail_msg("Failed to create a file at %s\n", testfile);
 
-	for (i = 0; i < fd_size; i++) {
-		unsigned char byte = (unsigned char)i;
+	assert(fd_size % sizeof(buf) == 0);
+	for (i = 0; i < sizeof(buf); i++)
+		buf[i] = (unsigned char)i;
+	for (i = 0; i < fd_size; i += sizeof(buf))
+		write(*fd, buf, sizeof(buf));
 
-		write(*fd, &byte, sizeof(byte));
-	}
 	close(*fd);
 	sync();
 	*fd = open("/proc/sys/vm/drop_caches", O_WRONLY);
@@ -341,6 +441,7 @@ int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd,
 
 	for (size_t i = 0; i < fd_size; i++)
 		dummy += *(*addr + i);
+	asm volatile("" : "+r" (dummy));
 
 	if (!check_huge_file(*addr, fd_size / pmd_pagesize, pmd_pagesize)) {
 		ksft_print_msg("No large pagecache folio generated, please provide a filesystem supporting large folio\n");
@@ -359,7 +460,8 @@ err_out_unlink:
 	return -1;
 }
 
-void split_thp_in_pagecache_to_order(size_t fd_size, int order, const char *fs_loc)
+void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
+		int order, int offset)
 {
 	int fd;
 	char *addr;
@@ -377,7 +479,12 @@ void split_thp_in_pagecache_to_order(size_t fd_size, int order, const char *fs_l
 		return;
 	err = 0;
 
-	write_debugfs(PID_FMT, getpid(), (uint64_t)addr, (uint64_t)addr + fd_size, order);
+	if (offset == -1)
+		write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
+			      (uint64_t)addr + fd_size, order);
+	else
+		write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
+			      (uint64_t)addr + fd_size, order, offset);
 
 	for (i = 0; i < fd_size; i++)
 		if (*(addr + i) != (char)i) {
@@ -396,9 +503,15 @@ out:
 	munmap(addr, fd_size);
 	close(fd);
 	unlink(testfile);
-	if (err)
-		ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d failed\n", order);
-	ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d passed\n", order);
+	if (offset == -1) {
+		if (err)
+			ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d failed\n", order);
+		ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d passed\n", order);
+	} else {
+		if (err)
+			ksft_exit_fail_msg("Split PMD-mapped pagecache folio to order %d at in-folio offset %d failed\n", order, offset);
+		ksft_test_result_pass("Split PMD-mapped pagecache folio to order %d at in-folio offset %d passed\n", order, offset);
+	}
 }
 
 int main(int argc, char **argv)
@@ -409,6 +522,7 @@ int main(int argc, char **argv)
 	char fs_loc_template[] = "/tmp/thp_fs_XXXXXX";
 	const char *fs_loc;
 	bool created_tmp;
+	int offset;
 
 	ksft_print_header();
 
@@ -420,7 +534,7 @@ int main(int argc, char **argv)
 	if (argc > 1)
 		optional_xfs_path = argv[1];
 
-	ksft_set_plan(3+9);
+	ksft_set_plan(1+8+1+9+9+8*4+2);
 
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
@@ -430,14 +544,26 @@ int main(int argc, char **argv)
 
 	fd_size = 2 * pmd_pagesize;
 
-	split_pmd_thp();
+	split_pmd_zero_pages();
+
+	for (i = 0; i < 9; i++)
+		if (i != 1)
+			split_pmd_thp_to_order(i);
+
 	split_pte_mapped_thp();
-	split_file_backed_thp();
+	for (i = 0; i < 9; i++)
+		split_file_backed_thp(i);
 
 	created_tmp = prepare_thp_fs(optional_xfs_path, fs_loc_template,
 			&fs_loc);
 	for (i = 8; i >= 0; i--)
-		split_thp_in_pagecache_to_order(fd_size, i, fs_loc);
+		split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, -1);
+
+	for (i = 0; i < 9; i++)
+		for (offset = 0;
+		     offset < pmd_pagesize / pagesize;
+		     offset += MAX(pmd_pagesize / pagesize / 4, 1 << i))
+			split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, offset);
 	cleanup_thp_fs(fs_loc, created_tmp);
 
 	ksft_finished();