[PATCH 4/4] selftests/mm: check after-split folio orders in split_huge_page_test.

[Zi Yan <ziy@nvidia.com>]

Instead of just checking the existence of PMD folios before and after folio
split tests, use check_folio_orders() to check after-split folio orders.

The following tests are not changed:
1. split_pte_mapped_thp: the test already uses kpageflags to check;
2. split_file_backed_thp: no vaddr available.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 .../selftests/mm/split_huge_page_test.c       | 67 +++++++++++++------
 1 file changed, 46 insertions(+), 21 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 3c761228e451..cd34000279fe 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -25,6 +25,10 @@
 uint64_t pagesize;
 unsigned int pageshift;
 uint64_t pmd_pagesize;
+unsigned int pmd_order;
+unsigned int max_order;
+
+#define NR_ORDERS (max_order + 1)
 
 #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
 #define SMAP_PATH "/proc/self/smaps"
@@ -38,6 +42,11 @@ uint64_t pmd_pagesize;
 #define KPF_THP      (1UL<<22)
 #define GET_ORDER(nr_pages)    (31 - __builtin_clz(nr_pages))
 
+const char *pagemap_proc = "/proc/self/pagemap";
+const char *kpageflags_proc = "/proc/kpageflags";
+int pagemap_fd;
+int kpageflags_fd;
+
 int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
 {
 	uint64_t paddr;
@@ -153,6 +162,7 @@ void split_pmd_thp_to_order(int order)
 	char *one_page;
 	size_t len = 4 * pmd_pagesize;
 	size_t i;
+	int orders[NR_ORDERS];
 
 	one_page = memalign(pmd_pagesize, len);
 	if (!one_page)
@@ -174,6 +184,12 @@ void split_pmd_thp_to_order(int order)
 		if (one_page[i] != (char)i)
 			ksft_exit_fail_msg("%ld byte corrupted\n", i);
 
+	memset(orders, 0, sizeof(int) * NR_ORDERS);
+	orders[order] = 4 << (pmd_order - order);
+	if (check_folio_orders((uint64_t)one_page >> pageshift,
+			       len >> pageshift, pagemap_fd, kpageflags_fd,
+			       orders, NR_ORDERS))
+		ksft_exit_fail_msg("Unexpected THP split\n");
 
 	if (!check_huge_anon(one_page, 0, pmd_pagesize))
 		ksft_exit_fail_msg("Still AnonHugePages not split\n");
@@ -188,22 +204,6 @@ void split_pte_mapped_thp(void)
 	size_t len = 4 * pmd_pagesize;
 	uint64_t thp_size;
 	size_t i;
-	const char *pagemap_template = "/proc/%d/pagemap";
-	const char *kpageflags_proc = "/proc/kpageflags";
-	char pagemap_proc[255];
-	int pagemap_fd;
-	int kpageflags_fd;
-
-	if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0)
-		ksft_exit_fail_msg("get pagemap proc error: %s\n", strerror(errno));
-
-	pagemap_fd = open(pagemap_proc, O_RDONLY);
-	if (pagemap_fd == -1)
-		ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
-
-	kpageflags_fd = open(kpageflags_proc, O_RDONLY);
-	if (kpageflags_fd == -1)
-		ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
 
 	one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
 			MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
@@ -261,8 +261,6 @@ void split_pte_mapped_thp(void)
 
 	ksft_test_result_pass("Split PTE-mapped huge pages successful\n");
 	munmap(one_page, len);
-	close(pagemap_fd);
-	close(kpageflags_fd);
 }
 
 void split_file_backed_thp(int order)
@@ -471,6 +469,7 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
 	size_t i;
 	char testfile[INPUT_MAX];
 	int err = 0;
+	int orders[NR_ORDERS];
 
 	err = snprintf(testfile, INPUT_MAX, "%s/test", fs_loc);
 
@@ -482,12 +481,21 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
 		return;
 	err = 0;
 
-	if (offset == -1)
+	memset(orders, 0, sizeof(int) * NR_ORDERS);
+	if (offset == -1) {
 		write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
 			      (uint64_t)addr + fd_size, order);
-	else
+		orders[order] = fd_size / (pagesize << order);
+	} else {
+		int times = fd_size / pmd_pagesize;
+
 		write_debugfs(PID_FMT_OFFSET, getpid(), (uint64_t)addr,
 			      (uint64_t)addr + fd_size, order, offset);
+		for (i = order + 1; i < pmd_order; i++)
+			orders[i] = times;
+
+		orders[order] = 2 * times;
+	}
 
 	for (i = 0; i < fd_size; i++)
 		if (*(addr + i) != (char)i) {
@@ -496,6 +504,12 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size, const char *fs_loc,
 			goto out;
 		}
 
+	if (check_folio_orders((uint64_t)addr >> pageshift,
+				fd_size >> pageshift, pagemap_fd, kpageflags_fd,
+				orders, NR_ORDERS))
+		ksft_exit_fail_msg("Unexpected THP split\n");
+
+
 	if (!check_huge_file(addr, 0, pmd_pagesize)) {
 		ksft_print_msg("Still FilePmdMapped not split\n");
 		err = EXIT_FAILURE;
@@ -526,7 +540,6 @@ int main(int argc, char **argv)
 	const char *fs_loc;
 	bool created_tmp;
 	int offset;
-	unsigned int max_order;
 	unsigned int nr_pages;
 	unsigned int tests;
 
@@ -543,6 +556,7 @@ int main(int argc, char **argv)
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
 	pmd_pagesize = read_pmd_pagesize();
+	pmd_order = GET_ORDER(pmd_pagesize / pagesize);
 	if (!pmd_pagesize)
 		ksft_exit_fail_msg("Reading PMD pagesize failed\n");
 
@@ -551,6 +565,14 @@ int main(int argc, char **argv)
 	tests = 2 + (max_order - 1) + (2 * max_order) + (max_order - 1) * 4 + 2;
 	ksft_set_plan(tests);
 
+	pagemap_fd = open(pagemap_proc, O_RDONLY);
+	if (pagemap_fd == -1)
+		ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
+
+	kpageflags_fd = open(kpageflags_proc, O_RDONLY);
+	if (kpageflags_fd == -1)
+		ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
+
 	fd_size = 2 * pmd_pagesize;
 
 	split_pmd_zero_pages();
@@ -575,6 +597,9 @@ int main(int argc, char **argv)
 			split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i, offset);
 	cleanup_thp_fs(fs_loc, created_tmp);
 
+	close(pagemap_fd);
+	close(kpageflags_fd);
+
 	ksft_finished();
 
 	return 0;
-- 
2.47.2