tools/vm/page_owner_sort.c: use fprintf() to send error messages to stderr

Error messages should be send to stderr using fprintf() instead of
printf().

This work is coauthored by
        Yixuan Cao
        Shenghong Han
        Yinan Zhang
        Chongxi Zhao
        Yuhong Feng
        Yongqiang Liu

Link: https://lkml.kernel.org/r/20220401024856.767-1-yejiajian2018@email.szu.edu.cnSigned-off-by: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Shenghong Han <hanshenghong2019@email.szu.edu.cn>
Cc: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Yinan Zhang <zhangyinan2019@email.szu.edu.cn>
Cc: Chongxi Zhao <zhaochongxi2019@email.szu.edu.cn>
Cc: Yuhong Feng <yuhongf@szu.edu.cn>
Cc: Yongqiang Liu <liuyongqiang13@huawei.com>
Cc: Haowen Bai <baihaowen@meizu.com>
Cc: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/vm/page_owner_sort.c

@@ -186,7 +186,7 @@ static int search_pattern(regex_t *pattern, char *pattern_str, char *buf)
 
 	err = regexec(pattern, buf, 2, pmatch, REG_NOTBOL);
 	if (err != 0 || pmatch[1].rm_so == -1) {
-		printf("no matching pattern in %s\n", buf);
+		fprintf(stderr, "no matching pattern in %s\n", buf);
 		return -1;
 	}
 	val_len = pmatch[1].rm_eo - pmatch[1].rm_so;
@@ -202,7 +202,7 @@ static void check_regcomp(regex_t *pattern, const char *regex)
 
 	err = regcomp(pattern, regex, REG_EXTENDED | REG_NEWLINE);
 	if (err != 0 || pattern->re_nsub != 1) {
-		printf("Invalid pattern %s code %d\n", regex, err);
+		fprintf(stderr, "Invalid pattern %s code %d\n", regex, err);
 		exit(1);
 	}
 }
@@ -251,7 +251,7 @@ static int get_page_num(char *buf)
 	errno = 0;
 	order_val = strtol(order_str, &endptr, 10);
 	if (order_val > 64 || errno != 0 || endptr == order_str || *endptr != '\0') {
-		printf("wrong order in follow buf:\n%s\n", buf);
+		fprintf(stderr, "wrong order in follow buf:\n%s\n", buf);
 		return 0;
 	}
 
@@ -268,7 +268,7 @@ static pid_t get_pid(char *buf)
 	errno = 0;
 	pid = strtol(pid_str, &endptr, 10);
 	if (errno != 0 || endptr == pid_str || *endptr != '\0') {
-		printf("wrong/invalid pid in follow buf:\n%s\n", buf);
+		fprintf(stderr, "wrong/invalid pid in follow buf:\n%s\n", buf);
 		return -1;
 	}
 
@@ -286,7 +286,7 @@ static pid_t get_tgid(char *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);
+		fprintf(stderr, "wrong/invalid tgid in follow buf:\n%s\n", buf);
 		return -1;
 	}
 
@@ -304,7 +304,7 @@ static __u64 get_ts_nsec(char *buf)
 	errno = 0;
 	ts_nsec = strtoull(ts_nsec_str, &endptr, 10);
 	if (errno != 0 || endptr == ts_nsec_str || *endptr != '\0') {
-		printf("wrong ts_nsec in follow buf:\n%s\n", buf);
+		fprintf(stderr, "wrong ts_nsec in follow buf:\n%s\n", buf);
 		return -1;
 	}
 
@@ -321,7 +321,7 @@ static __u64 get_free_ts_nsec(char *buf)
 	errno = 0;
 	free_ts_nsec = strtoull(free_ts_nsec_str, &endptr, 10);
 	if (errno != 0 || endptr == free_ts_nsec_str || *endptr != '\0') {
-		printf("wrong free_ts_nsec in follow buf:\n%s\n", buf);
+		fprintf(stderr, "wrong free_ts_nsec in follow buf:\n%s\n", buf);
 		return -1;
 	}
 
@@ -337,7 +337,7 @@ static char *get_comm(char *buf)
 	search_pattern(&comm_pattern, comm_str, buf);
 	errno = 0;
 	if (errno != 0) {
-		printf("wrong comm in follow buf:\n%s\n", buf);
+		fprintf(stderr, "wrong comm in follow buf:\n%s\n", buf);
 		return NULL;
 	}
 
@@ -373,7 +373,7 @@ static void add_list(char *buf, int len)
 		return;
 	}
 	if (list_size == max_size) {
-		printf("max_size too small??\n");
+		fprintf(stderr, "max_size too small??\n");
 		exit(1);
 	}
 	if (!is_need(buf))
@@ -383,7 +383,7 @@ static void add_list(char *buf, int len)
 	list[list_size].comm = get_comm(buf);
 	list[list_size].txt = malloc(len+1);
 	if (!list[list_size].txt) {
-		printf("Out of memory\n");
+		fprintf(stderr, "Out of memory\n");
 		exit(1);
 	}
 	memcpy(list[list_size].txt, buf, len);
@@ -499,7 +499,8 @@ int main(int argc, char **argv)
 			errno = 0;
 			fc.pid = strtol(optarg, &endptr, 10);
 			if (errno != 0 || endptr == optarg || *endptr != '\0') {
-				printf("wrong/invalid pid in from the command line:%s\n", optarg);
+				fprintf(stderr, "wrong/invalid pid in from the command line:%s\n",
+						optarg);
 				exit(1);
 			}
 			break;
@@ -508,7 +509,8 @@ int main(int argc, char **argv)
 			errno = 0;
 			fc.tgid = strtol(optarg, &endptr, 10);
 			if (errno != 0 || endptr == optarg || *endptr != '\0') {
-				printf("wrong/invalid tgid in from the command line:%s\n", optarg);
+				fprintf(stderr, "wrong/invalid tgid in from the command line:%s\n",
+						optarg);
 				exit(1);
 			}
 			break;
@@ -519,7 +521,7 @@ int main(int argc, char **argv)
 			break;
 		case 4:
 			if (!parse_cull_args(optarg)) {
-				printf("wrong argument after --cull in from the command line:%s\n",
+				fprintf(stderr, "wrong argument after --cull option:%s\n",
 						optarg);
 				exit(1);
 			}
@@ -554,7 +556,7 @@ int main(int argc, char **argv)
 	list = malloc(max_size * sizeof(*list));
 	buf = malloc(BUF_SIZE);
 	if (!list || !buf) {
-		printf("Out of memory\n");
+		fprintf(stderr, "Out of memory\n");
 		exit(1);
 	}