[PATCH v4 0/6] mm/damon: add support for hugepages

[Usama Arif <usamaarif642@gmail.com>]

This includes adding support for larger folios in damon for paddr,
which means largers folios will have their access checked and will
be considered for different DAMOS actions like pageout, prioritization
and migration.

Patches 3-6 add support for DAMOS hugepage filter type. This is to
gather statistics to check if memory regions of specific access
tempratures are backed by hugepages of a size in a specific
range. This filter can help to observe and prove the effectivenes of
different schemes for shrinking/collapsing hugepages.

I have kept patches 1-2 as part of these series as the later patches
are dependent on them.

The corresponding damo PR is at https://github.com/damonitor/damo/pull/20.

v3 -> v4:
- Add support for large folios of all sizes, and not just
  PMD mapped hugepages (David and SJ).
- only get folio while checking access/ applying DAMOS
  scheme if the head page is also part of that region.

v2 -> v3:
- expose hugepage via sysfs even if the kernel is
  built without hugepage support. DAMON will just
  just return 0. (SJ Park)

v1 -> v2:
- Wrap DAMOS_FILTER_TYPE_HUGEPAGE case with
  CONFIG_PGTABLE_HAS_HUGE_LEAVES (SJ Park)

Usama Arif (6):
  mm/damon: have damon_get_folio return folio even for tail pages
  mm/damon/paddr: use damon_get_folio_in_region to obtain folio
  mm/damon/sysfs-schemes: add files for setting damos_filter->folio_size
  mm/damon: introduce DAMOS filter type hugepage
  Docs/ABI/damon: document DAMOS sysfs files to set the min/max
    folio_size
  Docs/admin-guide/mm/damon/usage: Document hugepage filter type

 .../ABI/testing/sysfs-kernel-mm-damon         | 12 +++
 Documentation/admin-guide/mm/damon/usage.rst  | 17 +++--
 include/linux/damon.h                         | 13 ++++
 mm/damon/core.c                               |  3 +
 mm/damon/ops-common.c                         |  2 +-
 mm/damon/paddr.c                              | 75 +++++++++++++++----
 mm/damon/sysfs-schemes.c                      | 54 +++++++++++++
 7 files changed, 151 insertions(+), 25 deletions(-)

-- 
2.43.5