Re: [PATCH v3 4/4] mm/page_owner: document page_owner filter features

["zhen.ni" <zhen.ni@easystack.cn>]

在 2026/4/29 09:35, SeongJae Park 写道:
> On Tue, 28 Apr 2026 15:11:12 +0800 Zhen Ni <zhen.ni@easystack.cn> wrote:
> 
>> Add documentation for the page_owner filter functionality, including:
>> - Print mode filter (full stack vs stack handle)
>> - NUMA node filter (single node, multiple nodes, ranges)
>> - Usage examples for both filters
>>
>> Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
>> ---
>>
>> Changes in v3:
>> - New patch to document filter features as requested by Andrew Morton
>> ---
>>   Documentation/mm/page_owner.rst | 55 ++++++++++++++++++++++++++++++++-
>>   1 file changed, 54 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/mm/page_owner.rst b/Documentation/mm/page_owner.rst
>> index 6b12f3b007ec..6261366d33fe 100644
>> --- a/Documentation/mm/page_owner.rst
>> +++ b/Documentation/mm/page_owner.rst
>> @@ -74,7 +74,17 @@ Usage
>>   
>>   3) Do the job that you want to debug.
>>   
>> -4) Analyze information from page owner::
>> +4) (Optional) Use filters to focus on specific memory allocations::
>> +
>> +    cd /sys/kernel/debug/page_owner_filter
>> +
>> +    # Print only stack handles instead of full traces
>> +    echo 1 > print_mode
>> +
>> +    # Filter by NUMA nodes
>> +    echo "0,2-3" > nid
> 
> Nit.  Other parts of the document uses tab for the indentation, while the above
> new snippet is using four spaces.  How about using tab for the consistency?
> 
>> +
>> +5) Analyze information from page owner::
>>   
>>   	cat /sys/kernel/debug/page_owner_stacks/show_stacks > stacks.txt
>>   	cat stacks.txt
>> @@ -238,6 +248,49 @@ Usage
>>   				./page_owner_sort <input> <output> --tgid=1,2,3
>>   				./page_owner_sort <input> <output> --name name1,name2
>>   
>> +Page Owner Filters
>> +==================
>> +
>> +The page_owner feature provides filtering capabilities to focus on specific
>> +memory allocations (e.g., by NUMA node). Filters are controlled through debugfs
>> +files in ``/sys/kernel/debug/page_owner_filter/``.
>> +
>> +Print Mode Filter
>> +-----------------
>> +
>> +The ``print_mode`` file controls the level of detail in stack trace output.
>> +
>> +Available modes:
>> +
>> +- ``0`` (default): Print full stack traces
>> +- ``1``: Print only stack handles
>> +
>> +The ``print_mode=1`` output format::
>> +
>> +    Page allocated via order 0, mask 0x42800(GFP_NOWAIT|__GFP_COMP),
>> +    pid 1, tgid 1 (systemd), ts 349667370 ns
>> +    PFN 0xa00a2 type Unmovable Block 1280 type Unmovable
>> +    Flags 0x33fffe0000004124(...)
>> +    handle: 17432583
> 
> Tab for indentation?
> 
>> +
>> +To retrieve the full stack trace for a handle, use::
>> +
>> +    cat /sys/kernel/debug/page_owner_stacks/show_stacks_handles
> 
> Tab?
> 
>> +
>> +NUMA Node Filter
>> +----------------
>> +
>> +The ``nid`` file filters pages by NUMA node. This is useful for NUMA-aware
>> +environments to analyze node-specific memory allocation.
>> +
>> +Supported input formats:
>> +
>> +- Single node: ``echo "2" > nid``
>> +- Multiple nodes: ``echo "0,2,3" > nid``
>> +- Node range: ``echo "0-3" > nid``
>> +- Mixed format: ``echo "0,2-4,7" > nid``
>> +- Disable filter: ``echo "-1" > nid``
>> +
>>   STANDARD FORMAT SPECIFIERS
>>   ==========================
>>   ::
>> -- 
>> 2.20.1
> 
> 
> Thanks,
> SJ
> 
> 
I will fix all instances to use tab .

Thanks,
Zhen