Re: [PATCH v6 0/3] mm/page_owner: add filter infrastructure for print_mode and NUMA filtering

[Michal Hocko <mhocko@suse.com>]

On Mon 11-05-26 20:40:07, zhen.ni wrote:
> 
> 
> 在 2026/5/11 20:23, Michal Hocko 写道:
> > On Mon 11-05-26 11:30:14, Zhen Ni wrote:
> > > Solution
> > > ========
> > > 
> > > This patch series introduces a flexible filter infrastructure with
> > > two initial filters:
> > > 
> > > 1. **Print Mode Filter**: Outputs only stack handles instead of
> > >     full stack traces. The handle-to-stack mapping can be retrieved
> > >     from the existing show_stacks_handles interface. This dramatically
> > >     reduces output size while preserving all allocation metadata.
> > > 
> > > 2. **NUMA Node Filter**: Allows filtering pages by specific NUMA node(s)
> > >     using flexible nodelist format, enabling targeted analysis of memory
> > >     issues in NUMA-aware deployments.
> > 
> > How does this work when there are multiple consumers of the interface?
> > E.g per numa tool to watch node lock page_owner information?
> > 
> I understand your concern about concurrent access. Are you asking
> about this scenario?
> 
> Scenario: Multiple tools monitoring different NUMA nodes
>   Tool 1: echo "0" > nid && cat page_owner > node0.log
>   Tool 2: echo "1" > nid && cat page_owner > node1.log
> 
> The current global filter implementation would have race conditions
> in this case.

That makes the interface rather broken in my eyes TBH. Is there any way
to make the filter local to the fd?
-- 
Michal Hocko
SUSE Labs