tools/vm/page_owner_sort: fix -f option

The -f option is to filter out the information of blocks whose memory has
not been released, I noticed some blocks should not be filtered out.

Commit 9cc7e96a ("mm/page_owner: record timestamp and pid") records
the allocation timestamp (ts_nsec) of all pages.

Commit 866b4852 ("mm/page_owner: record the timestamp of all pages
during free") records the free timestamp (free_ts_nsec) of all pages. 
When the page is allocated for the first time, the initial value of
free_ts_nsec is 0, and the corresponding time will be obtained when the
page is released.  But during reallocation the free_ts_nsec will not reset
to 0 again.  In particular, when page migration occurs, these two
timestamps will be the same.

Now page_owner_sort removes all text blocks whose free_ts_nsec is not 0
when using -f option.  However, this way can only select pages allocated
for the first time.  If a freed page is reallocated, free_ts_nsec will be
less than ts_nsec; if page migration occurs, the two timestamps will be
equal.  These cases should be considered as pages are not released.

So I fix the function is_need() to keep text blocks that meet the above
two conditions when using -f option.

Link: https://lkml.kernel.org/r/20220812155515.30846-1-caoyixuan2019@email.szu.edu.cnSigned-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Chongxi Zhao <zhaochongxi2019@email.szu.edu.cn>
Cc: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Yuhong Feng <yuhongf@szu.edu.cn>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Georgi Djakov <georgi.djakov@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/vm/page_owner_sort.c

@@ -470,7 +470,12 @@ static bool match_str_list(const char *str, char **list, int list_size)
 
 static bool is_need(char *buf)
 {
-	if ((filter & FILTER_UNRELEASE) && get_free_ts_nsec(buf) != 0)
+	__u64 ts_nsec, free_ts_nsec;
+
+	ts_nsec = get_ts_nsec(buf);
+	free_ts_nsec = get_free_ts_nsec(buf);
+
+	if ((filter & FILTER_UNRELEASE) && free_ts_nsec != 0 && ts_nsec < free_ts_nsec)
 		return false;
 	if ((filter & FILTER_PID) && !match_num_list(get_pid(buf), fc.pids, fc.pids_size))
 		return false;