selftests/mm: hugepage_settings: rename and rework get_free_hugepages()

...  to hugetlb_free_default_pages() for consistency with
hugetlb_nr_default_pages().

Make hugetlb_free_default_pages() use hugetlb_sysfs_path() helper instead
of parsing /proc/meminfo.

Link: https://lore.kernel.org/20260511162840.375890-28-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Luiz Capitulino <luizcap@redhat.com>
Tested-by: Sarthak Sharma <sarthak.sharma@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam@infradead.org>
Cc: Li Wang <li.wang@linux.dev>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/hugepage_settings.c

@@ -445,25 +445,6 @@ unsigned long default_huge_page_size(void)
 	return hps;
 }
 
-unsigned long get_free_hugepages(void)
-{
-	unsigned long fhp = 0;
-	char *line = NULL;
-	size_t linelen = 0;
-	FILE *f = fopen("/proc/meminfo", "r");
-
-	if (!f)
-		return fhp;
-	while (getline(&line, &linelen, f) > 0) {
-		if (sscanf(line, "HugePages_Free:      %lu", &fhp) == 1)
-			break;
-	}
-
-	free(line);
-	fclose(f);
-	return fhp;
-}
-
 static void hugetlb_sysfs_path(char *buf, size_t buflen,
 			       unsigned long size, const char *attr)
 {
@@ -488,3 +469,12 @@ void hugetlb_set_nr_pages(unsigned long size, unsigned long nr)
 
 	write_num(path, nr);
 }
+
+unsigned long hugetlb_free_pages(unsigned long size)
+{
+	char path[PATH_MAX];
+
+	hugetlb_sysfs_path(path, sizeof(path), size, "free_hugepages");
+
+	return read_num(path);
+}

tools/testing/selftests/mm/hugepage_settings.h

@@ -92,10 +92,10 @@ bool thp_is_enabled(void);
 
 int detect_hugetlb_page_sizes(unsigned long sizes[], int max);
 unsigned long default_huge_page_size(void);
-unsigned long get_free_hugepages(void);
 
 unsigned long hugetlb_nr_pages(unsigned long size);
 void hugetlb_set_nr_pages(unsigned long size, unsigned long nr);
+unsigned long hugetlb_free_pages(unsigned long size);
 
 static inline unsigned long hugetlb_nr_default_pages(void)
 {
@@ -117,4 +117,14 @@ static inline void hugetlb_set_nr_default_pages(unsigned long nr)
 	hugetlb_set_nr_pages(size, nr);
 }
 
+static inline unsigned long hugetlb_free_default_pages(void)
+{
+	unsigned long size = default_huge_page_size();
+
+	if (!size)
+		return 0;
+
+	return hugetlb_free_pages(size);
+}
+
 #endif /* __HUGEPAGE_SETTINGS_H__ */

tools/testing/selftests/mm/hugetlb-madvise.c

@@ -27,7 +27,7 @@
 
 #define validate_free_pages(exp_free)					\
 	do {								\
-		unsigned long fhp = get_free_hugepages();		\
+		unsigned long fhp = hugetlb_free_default_pages();		\
 		if (fhp != (exp_free))					\
 			ksft_exit_fail_msg("Unexpected number of free "	\
 				"huge pages %lu, expected %lu line %d\n", \
@@ -68,7 +68,7 @@ int main(int argc, char **argv)
 	if (!base_page_size)
 		ksft_exit_fail_msg("Unable to determine base page size\n");
 
-	free_hugepages = get_free_hugepages();
+	free_hugepages = hugetlb_free_default_pages();
 	if (free_hugepages < MIN_FREE_PAGES)
 		ksft_exit_skip("Not enough free huge pages (have %lu, need %d)\n", free_hugepages, MIN_FREE_PAGES);
 

tools/testing/selftests/mm/hugetlb_dio.c

@@ -93,7 +93,7 @@ static void run_dio_using_hugetlb(int fd, unsigned int start_off,
 		ksft_exit_fail_perror("lseek failed\n");
 
 	/* Get the free huge pages before allocation */
-	free_hpage_b = get_free_hugepages();
+	free_hpage_b = hugetlb_free_default_pages();
 	if (free_hpage_b == 0) {
 		close(fd);
 		ksft_exit_skip("No free hugepage, exiting!\n");
@@ -121,7 +121,7 @@ static void run_dio_using_hugetlb(int fd, unsigned int start_off,
 	munmap(orig_buffer, h_pagesize);
 
 	/* Get the free huge pages after unmap*/
-	free_hpage_a = get_free_hugepages();
+	free_hpage_a = hugetlb_free_default_pages();
 
 	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);
@@ -142,7 +142,7 @@ int main(void)
 	ksft_print_header();
 
 	/* Check if huge pages are free */
-	if (!get_free_hugepages())
+	if (!hugetlb_free_default_pages())
 		ksft_exit_skip("No free hugepage, exiting\n");
 
 	fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);

tools/testing/selftests/mm/hugetlb_fault_after_madv.c

@@ -78,7 +78,7 @@ int main(void)
 	ksft_print_msg("[INFO] detected default hugetlb page size: %zu KiB\n",
 		       huge_page_size / 1024);
 
-	free_hugepages = get_free_hugepages();
+	free_hugepages = hugetlb_free_default_pages();
 	if (free_hugepages != 1) {
 		ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",
 			       free_hugepages);

tools/testing/selftests/mm/hugetlb_madv_vs_map.c

@@ -89,7 +89,7 @@ int main(void)
 	ksft_print_header();
 	ksft_set_plan(1);
 
-	free_hugepages = get_free_hugepages();
+	free_hugepages = hugetlb_free_default_pages();
 
 	if (free_hugepages != 1)
 		ksft_exit_skip("This test needs one and only one page to execute. Got %lu\n",

tools/testing/selftests/mm/uffd-stress.c

@@ -481,7 +481,7 @@ int main(int argc, char **argv)
 	 * for racy extra reservation of hugepages.
 	 */
 	if (gopts->test_type == TEST_HUGETLB &&
-	   get_free_hugepages() < 2 * (bytes / gopts->page_size) + gopts->nr_parallel - 1)
+	   hugetlb_free_default_pages() < 2 * (bytes / gopts->page_size) + gopts->nr_parallel - 1)
 		ksft_exit_skip("Skipping userfaultfd... not enough hugepages\n");
 
 	gopts->nr_pages_per_cpu = bytes / gopts->page_size / gopts->nr_parallel;