+ mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache.patch added to mm-unstable branch

+ mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/shrinker: allocate shrinker_info_unit from a dedicated kmem_cache
has been added to the -mm mm-unstable branch.  Its filename is
     mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Konstantin Khorenko <khorenko@virtuozzo.com>
Subject: mm/shrinker: allocate shrinker_info_unit from a dedicated kmem_cache
Date: Mon, 19 Oct 2026 18:11:44 +0200

shrinker_info_unit holds BITS_PER_LONG atomic_long_t of deferred work plus
a one-word bitmap, 520 bytes on 64-bit.  kzalloc_node() takes it from
kmalloc-1k, so almost half of every unit is padding.

Allocate the units from a cache of their own, sized to the unit.  The
cache is not cache-line aligned: the counters of a unit already share
cache lines between shrinkers, and aligning the unit would only keep
neighbouring units off each other's boundary line, at the cost of part of
the saving.

Link: https://lore.kernel.org/20261019-vstor-144715-shrinker_info_unit-kmem_cache-v3-1-0fb061e09bf4@virtuozzo.com
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Harry Yoo (Meta) <harry@kernel.org>
Reviewed-by: Qi Zheng <qi.zheng@linux.dev>
Acked-by: Muchun Song <muchun.song@linux.dev>
Assisted-by: LLM
Cc: Dave Chinner <david@fromorbit.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
---

 include/linux/memcontrol.h |    1 +
 mm/memcontrol.c            |    2 ++
 mm/shrinker.c              |   11 +++++++++--
 3 files changed, 12 insertions(+), 2 deletions(-)

--- a/include/linux/memcontrol.h~mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache
+++ a/include/linux/memcontrol.h
@@ -1717,6 +1717,7 @@ static inline u64 mem_cgroup_get_socket_
 }
 #endif
 
+void shrinker_unit_cache_init(void);
 int alloc_shrinker_info(struct mem_cgroup *memcg);
 void free_shrinker_info(struct mem_cgroup *memcg);
 void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id);
--- a/mm/memcontrol.c~mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache
+++ a/mm/memcontrol.c
@@ -5984,6 +5984,8 @@ int __init mem_cgroup_init(void)
 	memcg_pn_cachep = KMEM_CACHE(mem_cgroup_per_node,
 				     SLAB_PANIC | SLAB_HWCACHE_ALIGN);
 
+	shrinker_unit_cache_init();
+
 	return 0;
 }
 
--- a/mm/shrinker.c~mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache
+++ a/mm/shrinker.c
@@ -12,6 +12,12 @@ DEFINE_MUTEX(shrinker_mutex);
 
 #ifdef CONFIG_MEMCG
 static int shrinker_nr_max;
+static struct kmem_cache *shrinker_unit_cachep;
+
+void __init shrinker_unit_cache_init(void)
+{
+	shrinker_unit_cachep = KMEM_CACHE(shrinker_info_unit, SLAB_PANIC);
+}
 
 static inline int shrinker_unit_size(int nr_items)
 {
@@ -33,7 +39,7 @@ static inline void shrinker_unit_free(st
 		if (!unit[i])
 			break;
 
-		kfree(unit[i]);
+		kmem_cache_free(shrinker_unit_cachep, unit[i]);
 		unit[i] = NULL;
 	}
 }
@@ -47,7 +53,8 @@ static inline int shrinker_unit_alloc(st
 	int i;
 
 	for (i = start; i < nr; i++) {
-		unit = kzalloc_node(sizeof(*unit), GFP_KERNEL, nid);
+		unit = kmem_cache_alloc_node(shrinker_unit_cachep,
+					     GFP_KERNEL | __GFP_ZERO, nid);
 		if (!unit) {
 			shrinker_unit_free(new, start);
 			return -ENOMEM;
_

Patches currently in -mm which might be from khorenko@virtuozzo.com are

mm-shrinker-allocate-shrinker_info_unit-from-a-dedicated-kmem_cache.patch