Re: [PATCH v11 1/4] mm/page_owner: add print_mode filter

[Andrew Morton]

On Thu, 25 Jun 2026 14:26:51 -0400 "Zi Yan" <ziy@xxxxxxxxxx> wrote:

> > +static ssize_t page_owner_write(struct file *file,
> > +				 const char __user *buf,
> > +				 size_t count, loff_t *ppos)
> > +{
> > +	char *kbuf;
> > +	char *orig;
> > +	char *token;
> > +	int ret;
> > +	size_t max_input_len;
> 
> This can be const size_t max_input_len = 32 with the comment above it.

I don't think that local adds any value, really.  How about

--- a/mm/page_owner.c~mm-page_owner-add-print_mode-filter-fix
+++ a/mm/page_owner.c
@@ -933,7 +933,6 @@ static ssize_t page_owner_write(struct f
 	char *orig;
 	char *token;
 	int ret;
-	size_t max_input_len;
 	struct page_owner_filter_state *state = file->private_data;
 	enum page_owner_print_mode new_print_mode;
 	unsigned long flags;
@@ -942,9 +941,7 @@ static ssize_t page_owner_write(struct f
 	 * Maximum input length for filter commands:
 	 * 32: print_mode command max length is 17 ("mode=stack_handle").
 	 */
-	max_input_len = 32;
-
-	if (count > max_input_len)
+	if (count > 32)
 		return -EINVAL;
 
 	kbuf = memdup_user_nul(buf, count);
_