tools/vm/page_owner_sort.c: support sorting by tgid and update documentation

When the "page owner" information is read, the information sorted
by TGID is expected.

As a result, the following adjustments have been made:

1. Add a new -P option to sort the information of blocks by TGID in
   ascending order.

2. Adjust the order of member variables in block_list strust to avoid
   one 4 byte hole.

3. Add -P option explanation in the document.

Link: https://lkml.kernel.org/r/20220301151438.166118-3-yejiajian2018@email.szu.edu.cnSigned-off-by: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Zhenliang Wei <weizhenliang@huawei.com>
Cc: Yinan Zhang <zhangyinan2019@email.szu.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/page_owner.rst

@@ -116,6 +116,7 @@ Usage
 		-a		Sort by memory allocation time.
 		-m		Sort by total memory.
 		-p		Sort by pid.
+		-P		Sort by tgid.
 		-r		Sort by memory release time.
 		-s		Sort by stack trace.
 		-t		Sort by times (default).

tools/vm/page_owner_sort.c

@@ -25,16 +25,18 @@
 struct block_list {
 	char *txt;
 	char *stacktrace;
+	__u64 ts_nsec;
+	__u64 free_ts_nsec;
 	int len;
 	int num;
 	int page_num;
 	pid_t pid;
-	__u64 ts_nsec;
-	__u64 free_ts_nsec;
+	pid_t tgid;
 };
 
 static regex_t order_pattern;
 static regex_t pid_pattern;
+static regex_t tgid_pattern;
 static regex_t ts_nsec_pattern;
 static regex_t free_ts_nsec_pattern;
 static struct block_list *list;
@@ -91,6 +93,13 @@ static int compare_pid(const void *p1, const void *p2)
 	return l1->pid - l2->pid;
 }
 
+static int compare_tgid(const void *p1, const void *p2)
+{
+	const struct block_list *l1 = p1, *l2 = p2;
+
+	return l1->tgid - l2->tgid;
+}
+
 static int compare_ts(const void *p1, const void *p2)
 {
 	const struct block_list *l1 = p1, *l2 = p2;
@@ -170,6 +179,24 @@ static pid_t get_pid(char *buf)
 
 }
 
+static pid_t get_tgid(char *buf)
+{
+	pid_t tgid;
+	char tgid_str[FIELD_BUFF] = {0};
+	char *endptr;
+
+	search_pattern(&tgid_pattern, tgid_str, buf);
+	errno = 0;
+	tgid = strtol(tgid_str, &endptr, 10);
+	if (errno != 0 || endptr == tgid_str || *endptr != '\0') {
+		printf("wrong/invalid tgid in follow buf:\n%s\n", buf);
+		return -1;
+	}
+
+	return tgid;
+
+}
+
 static __u64 get_ts_nsec(char *buf)
 {
 	__u64 ts_nsec;
@@ -231,6 +258,7 @@ static void add_list(char *buf, int len)
 	list[list_size].txt[len] = 0;
 	list[list_size].stacktrace = strchr(list[list_size].txt, '\n') ?: "";
 	list[list_size].pid = get_pid(buf);
+	list[list_size].tgid = get_tgid(buf);
 	list[list_size].ts_nsec = get_ts_nsec(buf);
 	list[list_size].free_ts_nsec = get_free_ts_nsec(buf);
 	list_size++;
@@ -249,6 +277,7 @@ static void usage(void)
 		"-s	Sort by the stack trace.\n"
 		"-t	Sort by times (default).\n"
 		"-p	Sort by pid.\n"
+		"-P	Sort by tgid.\n"
 		"-a	Sort by memory allocate time.\n"
 		"-r	Sort by memory release time.\n"
 		"-c	Cull by comparing stacktrace instead of total block.\n"
@@ -268,7 +297,7 @@ int main(int argc, char **argv)
 	struct stat st;
 	int opt;
 
-	while ((opt = getopt(argc, argv, "acfmprst")) != -1)
+	while ((opt = getopt(argc, argv, "acfmprstP")) != -1)
 		switch (opt) {
 		case 'a':
 			cmp = compare_ts;
@@ -294,6 +323,9 @@ int main(int argc, char **argv)
 		case 't':
 			cmp = compare_num;
 			break;
+		case 'P':
+			cmp = compare_tgid;
+			break;
 		default:
 			usage();
 			exit(1);
@@ -314,6 +346,7 @@ int main(int argc, char **argv)
 
 	check_regcomp(&order_pattern, "order\\s*([0-9]*),");
 	check_regcomp(&pid_pattern, "pid\\s*([0-9]*),");
+	check_regcomp(&tgid_pattern, "tgid\\s*([0-9]*) ");
 	check_regcomp(&ts_nsec_pattern, "ts\\s*([0-9]*)\\s*ns,");
 	check_regcomp(&free_ts_nsec_pattern, "free_ts\\s*([0-9]*)\\s*ns");
 	fstat(fileno(fin), &st);
@@ -373,6 +406,7 @@ int main(int argc, char **argv)
 	}
 	regfree(&order_pattern);
 	regfree(&pid_pattern);
+	regfree(&tgid_pattern);
 	regfree(&ts_nsec_pattern);
 	regfree(&free_ts_nsec_pattern);
 	return 0;