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The preferred demotion node (migration_target_control.nid) should be the one closest to the source node to minimize migration latency. Currently, a discrepancy exists where demote_folio_list() randomly selects an allowed node if the preferred node from next_demotion_node() is not set in mems_effective. To address it, update next_demotion_node() to select a preferred target against allowed nodes; and to return the closest demotion target if all preferred nodes are not in mems_effective via next_demotion_node(). It ensures that the preferred demotion target is consistently the closest available node to the source node. [akpm@linux-foundation.org: fix comment typo, per Shakeel] Link: https://lkml.kernel.org/r/20260114205305.2869796-3-bingjiao@google.com Signed-off-by: Bing Jiao <bingjiao@google.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@kernel.org> Cc: Gregory Price <gourry@gourry.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joshua Hahn <joshua.hahnjy@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Waiman Long <longman@redhat.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>