[PATCH 1/2] tools/vm/page_owner_sort.c: Sort by stacktrace before culling

From: Sean Anderson
Date: Wed Nov 24 2021 - 14:35:24 EST


The contents of page_owner have changed to include more information than
the stack trace. On a modern kernel, the blocks look like

Page allocated via order 0, mask 0x0(), pid 1, ts 165564237 ns, free_ts 0 ns
register_early_stack+0x4b/0x90
init_page_owner+0x39/0x250
kernel_init_freeable+0x11e/0x242
kernel_init+0x16/0x130

Sorting by the contents of .txt will result in almost no repeated pages, as
the pid, ts, and free_ts will almost never be the same. Instead, sort by
the contents of the stack trace, which we assume to be whatever is after
the first line.

Signed-off-by: Sean Anderson <seanga2@xxxxxxxxx>
---

tools/vm/page_owner_sort.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/vm/page_owner_sort.c b/tools/vm/page_owner_sort.c
index 9ebb84a9c731..9ad3772a294d 100644
--- a/tools/vm/page_owner_sort.c
+++ b/tools/vm/page_owner_sort.c
@@ -23,6 +23,7 @@

struct block_list {
char *txt;
+ char *stacktrace;
int len;
int num;
int page_num;
@@ -51,11 +52,11 @@ int read_block(char *buf, int buf_size, FILE *fin)
return -1; /* EOF or no space left in buf. */
}

-static int compare_txt(const void *p1, const void *p2)
+static int compare_stacktrace(const void *p1, const void *p2)
{
const struct block_list *l1 = p1, *l2 = p2;

- return strcmp(l1->txt, l2->txt);
+ return strcmp(l1->stacktrace ?: "", l2->stacktrace ?: "");
}

static int compare_num(const void *p1, const void *p2)
@@ -121,6 +122,7 @@ static void add_list(char *buf, int len)
list[list_size].page_num = get_page_num(buf);
memcpy(list[list_size].txt, buf, len);
list[list_size].txt[len] = 0;
+ list[list_size].stacktrace = strchr(list[list_size].txt, '\n');
list_size++;
if (list_size % 1000 == 0) {
printf("loaded %d\r", list_size);
@@ -199,7 +201,7 @@ int main(int argc, char **argv)

printf("sorting ....\n");

- qsort(list, list_size, sizeof(list[0]), compare_txt);
+ qsort(list, list_size, sizeof(list[0]), compare_stacktrace);

list2 = malloc(sizeof(*list) * list_size);
if (!list2) {
@@ -211,7 +213,7 @@ int main(int argc, char **argv)

for (i = count = 0; i < list_size; i++) {
if (count == 0 ||
- strcmp(list2[count-1].txt, list[i].txt) != 0) {
+ strcmp(list2[count-1].stacktrace, list[i].stacktrace) != 0) {
list2[count++] = list[i];
} else {
list2[count-1].num += list[i].num;
--
2.33.0