[RFC PATCH v2 0/6] mm/damon: introduce perf event based access check

[Akinobu Mita <akinobu.mita@gmail.com>]

DAMON currently only provides PTE accessed-bit based access check, this
patch series adds a new perf event based access check.

Since perf event-based access checks do not require modifying the PTE
accessed-bit for pages representing each damon region, it reduces the
overhead of monitoring at a fixed granularity of the page size.
Furthermore, this patch series also includes a feature that allows you
to set a minimum region size for each target, enabling you to monitor
at any fixed size greater than the page size for each target.

Using these features also requires modifications to damo, but these are
not included in this patch series and are currently under development in
the following branch:

* https://github.com/mita/damo/tree/damo-perf-for-v3.1.8

Any feedback or advice on the patch set would be greatly appreciated.

* v2
- reintroduce damon_operations->cleanup()
- introduce struct damon_access_report
- use struct damon_access_report instead of introducing struct
  damon_perf_record
- remove maximum region size setting

* v1
- https://lore.kernel.org/damon/20260123021014.26915-1-akinobu.mita@gmail.com/T/

* TODO
- Currently, it is possible to unintentionally specify a perf_event
  that cannot obtain either PERF_SAMPLE_ADDR or PERF_SAMPLE_PHYS_ADDR
- Check if it works in a virtual environment using vPMU

Akinobu Mita (6):
  mm/damon: reintroduce damon_operations->cleanup()
  mm/damon/core: introduce struct damon_access_report
  mm/damon/core: add common code for perf event based access check
  mm/damon/vaddr: support perf event based access check
  mm/damon/paddr: support perf event based access check
  mm/damon: allow user to set min size of region

 .../ABI/testing/sysfs-kernel-mm-damon         |  10 +
 include/linux/damon.h                         |  63 ++
 mm/damon/core.c                               |  77 ++-
 mm/damon/ops-common.h                         |  39 ++
 mm/damon/paddr.c                              | 105 ++-
 mm/damon/sysfs-common.c                       |  11 +
 mm/damon/sysfs-common.h                       |   1 +
 mm/damon/sysfs.c                              | 399 ++++++++++-
 mm/damon/tests/sysfs-kunit.h                  |   2 +
 mm/damon/tests/vaddr-kunit.h                  |   5 +-
 mm/damon/vaddr.c                              | 654 +++++++++++++++++-
 11 files changed, 1332 insertions(+), 34 deletions(-)

-- 
2.43.0