Re: [PATCH v11 2/4] mm/page_owner: add NUMA node filter

[Andrew Morton]

On Thu, 25 Jun 2026 15:27:57 -0400 "Zi Yan" <ziy@xxxxxxxxxx> wrote:

> >  
> >  	/*
> >  	 * Maximum input length for filter commands:
> > -	 * 32: print_mode command max length is 17 ("mode=stack_handle").
> > +	 * - 32: print_mode command max length is 17 ("mode=stack_handle")
> > +	 *        with sufficient buffer
> > +	 * - 6 * MAX_NUMNODES: worst case for nid list
> > +	 *   Worst case per node: ",NNNNN" (comma + 5-digit node number) = 6 bytes
> >  	 */
> > -	max_input_len = 32;
> > +	max_input_len = 32 + 6 * MAX_NUMNODES;
> >  
> >  	if (count > max_input_len)
> >  		return -EINVAL;
> 
> Hi Andrew,
> 
> This needs to be fixed as well.

yep, I did that in the obvious way:

@@ -934,14 +961,20 @@ static ssize_t page_owner_write(struct f
 	char *token;
 	int ret;
 	struct page_owner_filter_state *state = file->private_data;
+	nodemask_t new_nid_filter;
+	bool new_nid_filter_enabled;
 	enum page_owner_print_mode new_print_mode;
 	unsigned long flags;
 
 	/*
 	 * Maximum input length for filter commands:
-	 * 32: print_mode command max length is 17 ("mode=stack_handle").
+	 * - 32: print_mode command max length is 17 ("mode=stack_handle")
+	 *        with sufficient buffer
+	 * - 6 * MAX_NUMNODES: worst case for nid list
+	 *   Worst case per node: ",NNNNN" (comma + 5-digit node number) = 6
+	 *   bytes
 	 */
-	if (count > 32)
+	if (count > 32 + 6 * MAX_NUMNODES)
 		return -EINVAL;
 
 	kbuf = memdup_user_nul(buf, count);