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

[Zi Yan]

On 25 Jun 2026, at 15:20, Andrew Morton wrote:

> 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);
> _

Looks good to me.

Best Regards,
Yan, Zi