[PATCH v2 00/11] mm: memcontrol: constify the read side of the memcg API

[Tal Zussman]

The memcg accessors, lruvec helpers, and stat readers only read from
the memcg, folio, or lruvec they are given, but take non-const
pointers. Constify them, along with a couple other helper functions in
mm/page_counter.c along the way.

This started as a follow-up to [1] that quickly grew in proportions :)

[1]: https://lore.kernel.org/linux-mm/anYqSDnC2BbJXv1h@xxxxxxxxxxxxxxxxxxxx/

---
Changes in v2:
- Patch 3: Constify the folio argument of folio_lruvec_relock_irq() and
  folio_lruvec_relock_irqsave() as well, per Sashiko
- Patch 3: Note that mem_cgroup_lruvec() updates lruvec->pgdat in the
  per-node structure, not the memcg, per Sashiko
- Patches 3 and 8: Use container_of_const() in lruvec_memcg() and the
  lruvec_page_state() family, per Sashiko
- Link to v1: https://patch.msgid.link/20260902-folio_memcg-const-v1-0-e2c1da22246d@xxxxxxxxxxxx

---
Tal Zussman (11):
      mm: memcontrol: take a const folio in folio_memcg() and friends
      mm: memcontrol: constify obj_cgroup_memcg() and friends
      mm: memcontrol: constify the lruvec helpers
      mm/page_io: take a const folio in bio_associate_blkg_from_folio()
      mm: memcontrol: constify the mem_cgroup accessors
      mm: page_counter: constify page_counter_read() and page_counter_margin()
      mm: memcontrol: constify the reclaim protection helpers
      mm: memcontrol: constify the memcg and lruvec stat readers
      mm: memcontrol: constify the swap accounting helpers
      mm: memcontrol: constify mem_cgroup_swappiness() and mem_cgroup_get_max()
      mm: memcontrol: constify the zswap and socket pressure helpers

 include/linux/memcontrol.h   | 204 ++++++++++++++++++++++---------------------
 include/linux/mmzone.h       |   2 +-
 include/linux/page_counter.h |   4 +-
 include/linux/swap.h         |  12 +--
 mm/memcontrol.c              |  49 ++++++-----
 mm/page_counter.c            |   2 +-
 mm/page_io.c                 |  14 +--
 mm/swap.h                    |   2 +-
 8 files changed, 148 insertions(+), 141 deletions(-)
---
base-commit: 9d3243fc689fef444f87e0a703b4c99653137e1b
change-id: 20260807-folio_memcg-const-4a67e40d485b

Best regards,
--  
Tal Zussman <tz2294@xxxxxxxxxxxx>