Re: [PATCH v3 0/7] mm/page_owner: add bpf_iter and kfuncs

[zhen.ni]

在 2026/10/22 02:52, Andrew Morton 写道:
> On Wed, 21 Oct 2026 19:24:30 +0800 Zhen Ni <zhen.ni@xxxxxxxxxxxx> wrote:
>
> > page_owner records who allocated every page and is a core memory-debug
> > facility, but it currently reaches userspace as the debugfs flat dump:
> > slicing allocations by pid, comm, NUMA node, cgroup or stack, etc.,
> > means streaming and parsing the entire file in userspace, which is
> > expensive on large hosts and hard to query live.
>
> Confused.  Your series 8570b65220e8 ("mm/page_owner: add print_mode
> filter") addressed this significantly?

Thank you. I'd like to share some background on how this new approach
came about.

After series 8570b65220e8 ("mm/page_owner: add print_mode filter"), I
attempted to further extend the filter capabilities so that userspace
could more selectively capture page owner results. This effort led to
the series [PATCH v3 0/8] mm/page_owner: Add PID/TGID/COMM and cgroup
filtering.

During that discussion, we gradually reached a consensus that "a BPF
iter" might be a better solution to this problem. The main concerns
with continuing to extend the kernel-side filter approach were:

 1. As filter capabilities grow, the kernel side needs to handle
 increasingly complex parameter parsing and various combinations of
 different filter attributes, which is not conducive to maintainability.

 2. More fundamentally, kernel-side filters cannot provide truly
 flexible filtering because the filtering logic is hardcoded in the
 kernel.

At that point, I did a POC to verify the BPF iter direction:

 
https://lore.kernel.org/linux-mm/99a94068-ab37-47c0-878c-7c1ada5204b2@xxxxxxxxxxxx/

It seems there is broad agreement on this direction. This new series is
the implementation of that approach.


Thanks,
Zhen