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8a90519585
sc_swappiness() had two separate definitions depending on CONFIG_MEMCG.
The !CONFIG_MEMCG variant simply returned vm_swappiness, ignoring the
proactive_swappiness value passed through scan_control. This caused the
swappiness parameter written to /sys/devices/system/node/nodeX/reclaim to
have no effect when CONFIG_MEMCG is disabled.
Fix this by consolidating sc_swappiness() into a single definition that
checks sc->proactive_swappiness first, then falls back to
mem_cgroup_swappiness() which already handles both CONFIG_MEMCG and
!CONFIG_MEMCG.
Before fix (swappiness=max ignored, mostly file pages reclaimed):
# cat /proc/sys/vm/swappiness
60
# cat /proc/vmstat | grep pgsteal
pgsteal_kswapd 0
pgsteal_direct 0
pgsteal_khugepaged 0
pgsteal_proactive 1840
pgsteal_anon 25
pgsteal_file 1815
# echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim
# cat /proc/vmstat | grep pgsteal
pgsteal_kswapd 0
pgsteal_direct 0
pgsteal_khugepaged 0
pgsteal_proactive 18013
pgsteal_anon 337
pgsteal_file 17676
After fix (swappiness=max honored, anon pages reclaimed as expected):
# cat /proc/vmstat | grep pgsteal
pgsteal_kswapd 0
pgsteal_direct 0
pgsteal_khugepaged 0
pgsteal_proactive 0
pgsteal_anon 0
pgsteal_file 0
# echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim
# cat /proc/vmstat | grep pgsteal
pgsteal_kswapd 0
pgsteal_direct 0
pgsteal_khugepaged 0
pgsteal_proactive 16283
pgsteal_anon 16283
pgsteal_file 0
Link: https://lore.kernel.org/20260723032434.2016749-3-ridong.chen@linux.dev
Fixes: b980077899 ("mm: introduce per-node proactive reclaim interface")
Signed-off-by: Ridong Chen <chenridong@xiaomi.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Tested-by: Song Hu <husong@kylinos.cn>
Reviewed-by: Song Hu <husong@kylinos.cn>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: <stable@vger.kernel.org> [6.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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