[PATCH v7 4/4] mm,page_owner: Filter out stacks by a threshold

Oscar Salvador
2024-02-08T23:45:23Z

We want to be able to filter out the stacks based on
a threshold we can tune.
By writing to 'page_owner_threshold' file, we can adjust
the threshold value.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
mm/page_owner.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index aea212734557..d95a73cf2581 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -780,14 +780,18 @@ static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
return stack;
}

+static unsigned long page_owner_stack_threshold;
+
static int stack_print(struct seq_file *m, void *v)
{
char *buf;
int ret = 0;
struct stack_iterator *iter = m->private;
struct stack_record *stack = iter->last_stack;
+ int stack_count = refcount_read(&stack->count);

- if (!stack->size || stack->size < 0 || refcount_read(&stack->count) < 2)
+ if (!stack->size || stack->size < 0 || stack_count < 2 ||
+ stack_count < page_owner_stack_threshold)
return 0;

buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
@@ -832,6 +836,21 @@ const struct file_operations page_owner_stack_operations = {
.release = seq_release,
};

+static int page_owner_threshold_get(void *data, u64 *val)
+{
+ *val = page_owner_stack_threshold;
+ return 0;
+}
+
+static int page_owner_threshold_set(void *data, u64 val)
+{
+ page_owner_stack_threshold = val;
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
+ &page_owner_threshold_set, "%llu");
+
static int __init pageowner_init(void)
{
if (!static_branch_unlikely(&page_owner_inited)) {
@@ -843,6 +862,8 @@ static int __init pageowner_init(void)
&proc_page_owner_operations);
debugfs_create_file("page_owner_stacks", 0400, NULL, NULL,
&page_owner_stack_operations);
+ debugfs_create_file("page_owner_threshold", 0600, NULL, NULL,
+ &proc_page_owner_threshold);

return 0;
}
--
2.43.0