[PATCH v7 0/2] mm/vmscan: fix demotion targets checks in reclaim/demotion

[Bing Jiao]

Hi Andrew,

I am sorry for issuing a new patch version after v6 has been merged into
mm-hotfixes-unstable.

Main updates in v7:

1. Fixed a bug in v6.

   Specifically, next_demotion_node() may return NUMA_NO_NODE if nodes
   were hot-unplugged. V6 directly checks
   node_isset(target_nid, allowed_mask), which will cause out-of-boundary
   bug if target_nid is NUMA_NO_NODE (-1).

2. Preferred node selection.

   [Patch 1/2] originally implemented a random selection from
   allowed nodes if the preferred node from next_demotion_node()
   was missing from mems_allowed. This behavior contradicts the
   purpose of migration_target_control.nid, which is intended to
   identify the preferred node nearest to the source.

   To resolve this inconsistency, incorporat the preferred node
   selection patch into this series.


If there is a consensus among reviewers to backport Patch 2/2
alongside Patch 1/2, they can be combined.
Otherwise, I will post Patch 2/2 in another series.

Many thanks!

Best regards,
Bing

Bing Jiao (2):
  mm/vmscan: fix demotion targets checks in reclaim/demotion
  mm/vmscan: select the closest preferred node in demote_folio_list()

 include/linux/cpuset.h       |  6 ++--
 include/linux/memcontrol.h   |  6 ++--
 include/linux/memory-tiers.h |  6 ++--
 kernel/cgroup/cpuset.c       | 54 ++++++++++++++++++++++++------------
 mm/memcontrol.c              | 16 +++++++++--
 mm/memory-tiers.c            | 11 +++++---
 mm/vmscan.c                  | 49 +++++++++++++++++++++++++-------
 7 files changed, 105 insertions(+), 43 deletions(-)

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2.52.0.457.g6b5491de43-goog