Re: [PATCH v2 1/3] mm/page_owner: add filter infrastructure

[Zi Yan <ziy@nvidia.com>]

On 27 Apr 2026, at 23:33, zhen.ni wrote:

> 在 2026/4/27 23:35, Zi Yan 写道:
>> On 19 Apr 2026, at 11:55, Zhen Ni wrote:
>>
>>> Add data structure for page_owner filtering functionality and create
>>> debugfs directory for filter controls.
>>>
>>> This adds:
>>> - enum page_owner_print_mode with values for full_stack and stack_handle
>>> - struct page_owner_filter with print_mode and nid_mask fields
>>> - Static owner_filter instance initialized with default values
>>> - page_owner_filter debugfs directory
>>>
>>> The filter infrastructure will be used to add print_mode and NUMA node
>>> filtering capabilities in subsequent commits.
>>>
>>> Link: https://lore.kernel.org/linux-mm/20260417154638.22370-2-zhen.ni@easystack.cn/
>>> Suggested-by: Zi Yan <ziy@nvidia.com>
>>> Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
>>> ---
>>>
>>> Changes in v2:
>>> - Use enum page_owner_print_mode instead of bool 'compact' for better clarity
>>> - Use nodemask_t instead of int 'nid' to support multi-node filtering
>>> ---
>>>   mm/page_owner.c | 20 +++++++++++++++++++-
>>>   1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> The patch can be folded into Patch 2. Otherwise, these new types are not
>> used and page_owner_filter folder is just empty.
>>
>
>
> Thanks for your review and suggestion.
>
> I kept the 3-patch structure mainly for clear functional separation,
> which also makes review easier. Patch 1 adds the infrastructure,

What is the point of adding unused code in a separate patch?
Patch 1 has no functional addition and should be part of Patch 2.

> patch 2 adds print_mode filter, and patch 3 adds NUMA filter.
>
> I discussed this with Andrew and he has already accepted the
> current 3-patch structure into mm-new for testing. Since he's okay
> with it and mentioned that bisection holes are acceptable in this

The patches are still in mm-new, not mm-stable. It is totally acceptable
to reorganize them.

> case, I'll keep the current structure in v3.

Please refrain from posting a new version when the discussion is still
going on.

>
>>>
>>> diff --git a/mm/page_owner.c b/mm/page_owner.c
>>> index 8178e0be557f..5884d883837e 100644
>>> --- a/mm/page_owner.c
>>> +++ b/mm/page_owner.c
>>> @@ -54,6 +54,21 @@ struct stack_print_ctx {
>>>   	u8 flags;
>>>   };
>>>
>>> +enum page_owner_print_mode {
>>> +	PAGE_OWNER_PRINT_FULL_STACK,
>>> +	PAGE_OWNER_PRINT_STACK_HANDLE,
>>> +};
>>> +
>>> +struct page_owner_filter {
>>> +	enum page_owner_print_mode print_mode;
>>> +	nodemask_t nid_mask;
>>> +};
>>> +
>>> +static struct page_owner_filter owner_filter = {
>>> +	.print_mode = PAGE_OWNER_PRINT_FULL_STACK,
>>> +	.nid_mask = NODE_MASK_NONE,
>>> +};
>>> +
>>>   static bool page_owner_enabled __initdata;
>>>   DEFINE_STATIC_KEY_FALSE(page_owner_inited);
>>>
>>> @@ -973,7 +988,7 @@ DEFINE_SIMPLE_ATTRIBUTE(page_owner_threshold_fops, &page_owner_threshold_get,
>>>
>>>   static int __init pageowner_init(void)
>>>   {
>>> -	struct dentry *dir;
>>> +	struct dentry *dir, *filter_dir;
>>>
>>>   	if (!static_branch_unlikely(&page_owner_inited)) {
>>>   		pr_info("page_owner is disabled\n");
>>> @@ -981,6 +996,9 @@ 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);
>>> +
>>>   	dir = debugfs_create_dir("page_owner_stacks", NULL);
>>>   	debugfs_create_file("show_stacks", 0400, dir,
>>>   			    (void *)(STACK_PRINT_FLAG_STACK |
>>> -- 
>>> 2.20.1
>>
>>
>> Best Regards,
>> Yan, Zi
>>
>>
> Best regards,
> Zhen


Best Regards,
Yan, Zi