linux-kernel - [PATCH] tools/vm/page_owner

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Date:   Fri, 12 Aug 2022 23:55:15 +0800
From:   Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
To:     akpm@...ux-foundation.org
Cc:     zhaochongxi2019@...il.szu.edu.cn, yejiajian2018@...il.szu.edu.cn,
        linux-kernel@...r.kernel.org, yuhongf@....edu.cn,
        Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
Subject: [PATCH] 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 <9cc7e96aa846> ("mm/page_owner: record timestamp and pid")
records the allocation timestamp (ts_nsec) of all pages.

Commit <866b48526217> ("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.

Signed-off-by: Yixuan Cao <caoyixuan2019@...il.szu.edu.cn>
---
 tools/vm/page_owner_sort.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/vm/page_owner_sort.c b/tools/vm/page_owner_sort.c
index ec2e67c85b84..ce860ab94162 100644
--- a/tools/vm/page_owner_sort.c
+++ b/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;
-- 
2.17.1