tools/mm: filter out timestamps for correct collation

With the introduction of allocation timestamps being included in
page_owner output, each record becomes unique due to the timestamp
nanosecond granularity.  Remove the check in add_list that tries to
collate each record during processing as the memcmp() is just additional
overhead at this point.

Also keep the allocation timestamps, but allow collation to occur without
consideration of the allocation timestamp except in the case were
allocation timestamps are requested by the user (the -a option).

Link: https://lkml.kernel.org/r/20231013190350.579407-4-audra@redhat.comSigned-off-by: Audra Mitchell <audra@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Georgi Djakov <djakov@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/mm/page_owner_sort.c

@@ -203,6 +203,21 @@ static int compare_sort_condition(const void *p1, const void *p2)
 	return cmp;
 }
 
+static int remove_pattern(regex_t *pattern, char *buf, int len)
+{
+	regmatch_t pmatch[2];
+	int err;
+
+	err = regexec(pattern, buf, 2, pmatch, REG_NOTBOL);
+	if (err != 0 || pmatch[1].rm_so == -1)
+		return len;
+
+	memcpy(buf + pmatch[1].rm_so,
+		buf + pmatch[1].rm_eo, len - pmatch[1].rm_eo);
+
+	return len - (pmatch[1].rm_eo - pmatch[1].rm_so);
+}
+
 static int search_pattern(regex_t *pattern, char *pattern_str, char *buf)
 {
 	int err, val_len;
@@ -443,13 +458,6 @@ static bool is_need(char *buf)
 
 static bool add_list(char *buf, int len, char *ext_buf)
 {
-	if (list_size != 0 &&
-		len == list[list_size-1].len &&
-		memcmp(buf, list[list_size-1].txt, len) == 0) {
-		list[list_size-1].num++;
-		list[list_size-1].page_num += get_page_num(buf);
-		return true;
-	}
 	if (list_size == max_size) {
 		fprintf(stderr, "max_size too small??\n");
 		return false;
@@ -465,6 +473,9 @@ static bool add_list(char *buf, int len, char *ext_buf)
 		return false;
 	}
 	memcpy(list[list_size].txt, buf, len);
+	if (sc.cmps[0] != compare_ts) {
+		len = remove_pattern(&ts_nsec_pattern, list[list_size].txt, len);
+	}
 	list[list_size].txt[len] = 0;
 	list[list_size].len = len;
 	list[list_size].num = 1;