selftests/mm: support multi-size THP interface in thp_settings

Save and restore the new per-size hugepage enabled setting, if available
on the running kernel.

Since the number of per-size directories is not fixed, solve this as
simply as possible by catering for a maximum number in the thp_settings
struct (20). Each array index is the order. The value of THP_NEVER is
changed to 0 so that all of these new settings default to THP_NEVER and
the user only needs to fill in the ones they want to enable.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ryan Roberts <[e-mail]>
Tested-by: Kefeng Wang <[e-mail]>
Tested-by: John Hubbard <[e-mail]>
Cc: Alistair Popple <[e-mail]>
Cc: Anshuman Khandual <[e-mail]>
Cc: Barry Song <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: "Huang, Ying" <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Itaru Kitayama <[e-mail]>
Cc: Kirill A. Shutemov <[e-mail]>
Cc: Luis Chamberlain <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Cc: Yang Shi <[e-mail]>
Cc: Yin Fengwei <[e-mail]>
Cc: Yu Zhao <[e-mail]>
Cc: Zi Yan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/mm/khugepaged.c

···
 
 int main(int argc, const char **argv)
 {
+	int hpage_pmd_order;
 	struct thp_settings default_settings = {
 		.thp_enabled = THP_MADVISE,
 		.thp_defrag = THP_DEFRAG_ALWAYS,
···
 		exit(EXIT_FAILURE);
 	}
 	hpage_pmd_nr = hpage_pmd_size / page_size;
+	hpage_pmd_order = __builtin_ctz(hpage_pmd_nr);
 
 	default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;
 	default_settings.khugepaged.max_ptes_swap = hpage_pmd_nr / 8;
 	default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2;
 	default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
+	default_settings.hugepages[hpage_pmd_order].enabled = THP_INHERIT;
 
 	save_settings();
 	thp_push_settings(&default_settings);

tools/testing/selftests/mm/thp_settings.c

···
 static char dev_queue_read_ahead_path[PATH_MAX];
 
 static const char * const thp_enabled_strings[] = {
-	"always",
-	"madvise",
 	"never",
+	"always",
+	"inherit",
+	"madvise",
 	NULL
 };
 
···
 
 void thp_read_settings(struct thp_settings *settings)
 {
+	unsigned long orders = thp_supported_orders();
+	char path[PATH_MAX];
+	int i;
+
 	*settings = (struct thp_settings) {
 		.thp_enabled = thp_read_string("enabled", thp_enabled_strings),
 		.thp_defrag = thp_read_string("defrag", thp_defrag_strings),
···
 	};
 	if (dev_queue_read_ahead_path[0])
 		settings->read_ahead_kb = read_num(dev_queue_read_ahead_path);
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		if (!((1 << i) & orders)) {
+			settings->hugepages[i].enabled = THP_NEVER;
+			continue;
+		}
+		snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		settings->hugepages[i].enabled =
+			thp_read_string(path, thp_enabled_strings);
+	}
 }
 
 void thp_write_settings(struct thp_settings *settings)
 {
 	struct khugepaged_settings *khugepaged = &settings->khugepaged;
+	unsigned long orders = thp_supported_orders();
+	char path[PATH_MAX];
+	int enabled;
+	int i;
 
 	thp_write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
 	thp_write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
···
 
 	if (dev_queue_read_ahead_path[0])
 		write_num(dev_queue_read_ahead_path, settings->read_ahead_kb);
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		if (!((1 << i) & orders))
+			continue;
+		snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		enabled = settings->hugepages[i].enabled;
+		thp_write_string(path, thp_enabled_strings[enabled]);
+	}
 }
 
 struct thp_settings *thp_current_settings(void)
···
 	strncpy(dev_queue_read_ahead_path, path,
 		sizeof(dev_queue_read_ahead_path));
 	dev_queue_read_ahead_path[sizeof(dev_queue_read_ahead_path) - 1] = '\0';
+}
+
+unsigned long thp_supported_orders(void)
+{
+	unsigned long orders = 0;
+	char path[PATH_MAX];
+	char buf[256];
+	int ret;
+	int i;
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		ret = snprintf(path, PATH_MAX, THP_SYSFS "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		if (ret >= PATH_MAX) {
+			printf("%s: Pathname is too long\n", __func__);
+			exit(EXIT_FAILURE);
+		}
+
+		ret = read_file(path, buf, sizeof(buf));
+		if (ret)
+			orders |= 1UL << i;
+	}
+
+	return orders;
 }

tools/testing/selftests/mm/thp_settings.h

···
 #include <stdint.h>
 
 enum thp_enabled {
-	THP_ALWAYS,
-	THP_MADVISE,
 	THP_NEVER,
+	THP_ALWAYS,
+	THP_INHERIT,
+	THP_MADVISE,
 };
 
 enum thp_defrag {
···
 	SHMEM_FORCE,
 };
 
+#define NR_ORDERS 20
+
+struct hugepages_settings {
+	enum thp_enabled enabled;
+};
+
 struct khugepaged_settings {
 	bool defrag;
 	unsigned int alloc_sleep_millisecs;
···
 	bool use_zero_page;
 	struct khugepaged_settings khugepaged;
 	unsigned long read_ahead_kb;
+	struct hugepages_settings hugepages[NR_ORDERS];
 };
 
 int read_file(const char *path, char *buf, size_t buflen);
···
 void thp_save_settings(void);
 
 void thp_set_read_ahead_path(char *path);
+unsigned long thp_supported_orders(void);
 
 #endif /* __THP_SETTINGS_H__ */