Re: [PATCH 3/3] mm/page_owner: add NUMA node filter

[Zi Yan]

On 17 Apr 2026, at 11:46, Zhen Ni wrote:

> Add NUMA node filtering functionality to page_owner to allow
> filtering pages by specific NUMA node.

Would a NUMA node bitmask be more generally applicable?
For sysfs, input and output can be a list of NUMA nodes that will be printed.

>
> The filter allows users to focus on pages from a specific NUMA node,
> which is useful for NUMA-aware memory allocation analysis and debugging.
> Setting nid to -1 disables filtering (default behavior).
>
> Signed-off-by: Zhen Ni <zhen.ni@xxxxxxxxxxxx>
> ---
>  mm/page_owner.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 214b58eef3d8..ebc29f3f516d 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -726,6 +726,13 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>  		if (unlikely(!page_ext))
>  			continue;
>
> +		if (READ_ONCE(owner_filter.nid) >= 0) {
> +			int nid = page_to_nid(page);
> +
> +			if (nid != READ_ONCE(owner_filter.nid))
> +				goto ext_put_continue;
> +		}
> +
>  		/*
>  		 * Some pages could be missed by concurrent allocation or free,
>  		 * because we don't hold the zone lock.
> @@ -987,6 +994,24 @@ static int page_owner_threshold_set(void *data, u64 val)
>  DEFINE_SIMPLE_ATTRIBUTE(page_owner_threshold_fops, &page_owner_threshold_get,
>  			&page_owner_threshold_set, "%llu");
>
> +static int page_owner_nid_filter_get(void *data, u64 *val)
> +{
> +	*val = READ_ONCE(owner_filter.nid);
> +	return 0;
> +}
> +
> +static int page_owner_nid_filter_set(void *data, u64 val)
> +{
> +	if (val >= MAX_NUMNODES && val != (u64)-1)
> +		return -EINVAL;
> +	WRITE_ONCE(owner_filter.nid, val);
> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(page_owner_nid_filter_fops,
> +			&page_owner_nid_filter_get,
> +			&page_owner_nid_filter_set, "%lld");
> +
>  static int page_owner_compact_get(void *data, u64 *val)
>  {
>  	*val = READ_ONCE(owner_filter.compact);
> @@ -1018,6 +1043,8 @@ static int __init pageowner_init(void)
>  	debugfs_create_file("page_owner", 0400, NULL, NULL, &page_owner_fops);
>
>  	filter_dir = debugfs_create_dir("page_owner_filter", NULL);
> +	debugfs_create_file("nid", 0600, filter_dir, NULL,
> +			    &page_owner_nid_filter_fops);
>  	debugfs_create_file("compact", 0600, filter_dir, NULL,
>  			    &page_owner_compact_fops);
>
> -- 
> 2.20.1


Best Regards,
Yan, Zi