[failures] mm-thp-restore-shrinker_nonslab-on-the-deferred-split-shrinker.patch removed from -mm tree

[failures] mm-thp-restore-shrinker_nonslab-on-the-deferred-split-shrinker.patch removed from -mm tree

[Andrew Morton]

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The quilt patch titled
     Subject: mm: thp: restore SHRINKER_NONSLAB on the deferred split shrinker
has been removed from the -mm tree.  Its filename was
     mm-thp-restore-shrinker_nonslab-on-the-deferred-split-shrinker.patch

This patch was dropped because it had testing failures

------------------------------------------------------
From: Qinyun Tan <qinyuntan@linux.alibaba.com>
Subject: mm: thp: restore SHRINKER_NONSLAB on the deferred split shrinker
Date: Thu, 10 Sep 2026 16:07:21 +0800

On a system booted with cgroup.memory=nokmem, the deferred split shrinker
is demoted to a non-memcg-aware one.  As a result, partially unmapped THPs
are only split under global reclaim; memcg (limit-induced) reclaim never
splits them, so a cgroup under memory pressure keeps its underused THPs
intact.

The shrinker has carried SHRINKER_NONSLAB since commit 0a432dcbeb32 ("mm:
shrinker: make shrinker not depend on memcg kmem") precisely so it would
keep working with kmem accounting disabled.  Commit fafaeceb89a5 ("mm:
switch deferred split shrinker to list_lru") dropped it knowingly: under
nokmem the list_lru collapses into a shared per-node list while
__list_lru_add() still sets the shrinker bit on whichever memcg happens to
add the first item, and with the flag set the shrinker would run twice per
reclaim cycle [1].

NONSLAB-backed lrus keep their per-memcg lists under nokmem now, so the
shrinker bit identifies the owning memcg again.  Restore the flag.

This was noticed by Michal during review of the patch "mm/list_lru: don't
copy stale shrinker id from non-memcg-aware shrinkers" [2].

Link: https://lore.kernel.org/20260910080722.3961351-4-qinyuntan@linux.alibaba.com
Link: https://lore.kernel.org/all/ah9PGv12mqai84ES@cmpxchg.org/ [1]
Link: https://lore.kernel.org/lkml/697713c4-0857-485b-aba7-c74f37a3c8b4@linux.alibaba.com/ [2]
Fixes: fafaeceb89a5 ("mm: switch deferred split shrinker to list_lru")
Signed-off-by: Qinyun Tan <qinyuntan@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Usama Arif <usama.arif@linux.dev>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Yosry Ahmed <yosry@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Xunlei Pang <xlpang@linux.alibaba.com>
Cc: Kairui Song <ryncsn@gmail.com>
---

 mm/huge_memory.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/huge_memory.c~mm-thp-restore-shrinker_nonslab-on-the-deferred-split-shrinker
+++ a/mm/huge_memory.c
@@ -1059,7 +1059,8 @@ int folio_memcg_alloc_deferred(struct fo
 static int __init thp_shrinker_init(void)
 {
 	deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
-						 SHRINKER_MEMCG_AWARE,
+						 SHRINKER_MEMCG_AWARE |
+						 SHRINKER_NONSLAB,
 						 "thp-deferred_split");
 	if (!deferred_split_shrinker)
 		return -ENOMEM;
_

Patches currently in -mm which might be from qinyuntan@linux.alibaba.com are

mm-list_lru-disable-memcg-awareness-under-cgroup_disable=memory.patch
mm-list_lru-dont-copy-stale-shrinker-id-from-non-memcg-aware-shrinkers.patch
mm-zswap-mark-the-zswap-shrinker-shrinker_nonslab.patch