Hi
On 2024/2/16 5:59, Oscar Salvador wrote:
We want to be able to filter out the stacks based on a threshold we can
can tune.
By writing to 'count_threshold' file, we can adjust the threshold value.
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
---
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 e99fbf822dd6..e56c1e92eccf 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -846,6 +846,8 @@ 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)
{
int i, stack_count;
@@ -858,7 +860,8 @@ static int stack_print(struct seq_file *m, void *v)
entries = stack_record->entries;
stack_count = refcount_read(&stack_record->count) - 1;
- if (!nr_entries || nr_entries < 0 || stack_count < 1)
+ if (!nr_entries || nr_entries < 0 || stack_count < 1 ||
+ stack_count < page_owner_stack_threshold)
return 0;
for (i = 0; i < nr_entries; i++)
@@ -891,6 +894,22 @@ static const struct file_operations page_owner_stack_operations = {
.release = seq_release,
};
+static int page_owner_threshold_get(void *data, u64 *val)
+{
+ *val = READ_ONCE(page_owner_stack_threshold);
+ return 0;
+}
+
+static int page_owner_threshold_set(void *data, u64 val)
+{
+ WRITE_ONCE(page_owner_stack_threshold, val);
+ return 0;
+}
no need READ/WRITE_ONCE between get/set, since simple_attr_read/write()
with a mutex, but set and stack_print could date race
+
+DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
+ &page_owner_threshold_set, "%llu");
%llu\n"
In addition, since we have a stack_list, could we add a new feature to
dump stack info with threshold with OOM notifier, because many users
directly call alloc_page family, which makes it too difficult to debug
during OOM.
Thanks
+
+
static int __init pageowner_init(void)
{
struct dentry *dir;
@@ -905,6 +924,8 @@ static int __init pageowner_init(void)
dir = debugfs_create_dir("page_owner_stacks", NULL);
debugfs_create_file("show_stacks", 0400, dir, NULL,
&page_owner_stack_operations);
+ debugfs_create_file("count_threshold", 0600, dir, NULL,
+ &proc_page_owner_threshold);
return 0;
}
