Hi all, Introduction ============
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. Exposing the same walk to eBPF lets a program filter and aggregate in the kernel and surface only the records it cares about. This series adds that access as a seq_file bpf_iter target and an open-coded iterator. Implementation ============== The page walk is factored into page_owner_next_eligible(), shared by the read path and the iterators so eligibility stays identical. Three kfuncs expose information that a BPF program cannot decode from the snapshot alone: the NUMA node, per-page memcg info including the full cgroup path, and the stack trace behind a stack_depot handle. Each record is snapshotted under the page_ext RCU lock, so consumers read a consistent copy. Testing ======= The selftest exercises the seq_file and open-coded iterators, and validates the get_nid, stack_snprint and get_memcg_info kfuncs. Zhen Ni (6): mm/page_owner: extract page_owner_next_eligible() from read loop mm/page_owner: add bpf_iter target "page_owner" mm/page_owner: add open-coded page_owner iterator mm/page_owner: add bpf_page_owner_get_nid() kfunc mm/page_owner: add bpf_page_owner_get_memcg_info() kfunc selftests/bpf: add tests for the page_owner bpf_iter target kernel/bpf/helpers.c | 8 + mm/Makefile | 3 + mm/page_owner.c | 219 +++++++++++------- mm/page_owner.h | 58 +++++ mm/page_owner_iter.c | 180 ++++++++++++++ .../bpf/prog_tests/page_owner_iter.c | 173 ++++++++++++++ .../selftests/bpf/progs/bpf_iter_page_owner.c | 161 +++++++++++++ 7 files changed, 722 insertions(+), 80 deletions(-) create mode 100644 mm/page_owner.h create mode 100644 mm/page_owner_iter.c create mode 100644 tools/testing/selftests/bpf/prog_tests/page_owner_iter.c create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_page_owner.c -- 2.20.1
