+ mm-list_lru-dont-pass-unnecessary-key-parameters.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/list_lru: don't pass unnecessary key parameters
has been added to the -mm mm-unstable branch.  Its filename is
     mm-list_lru-dont-pass-unnecessary-key-parameters.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-list_lru-dont-pass-unnecessary-key-parameters.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: Kairui Song <kasong@tencent.com>
Subject: mm/list_lru: don't pass unnecessary key parameters
Date: Tue, 5 Nov 2024 01:52:52 +0800

Patch series "mm/list_lru: Split list_lru lock into per-cgroup scope".

When LOCKDEP is not enabled, lock_class_key is an empty struct that is
never used.  But the list_lru initialization function still takes a
placeholder pointer as parameter, and the compiler cannot optimize it
because the function is not static and exported.

Remove this parameter and move it inside the list_lru struct.  Only use it
when LOCKDEP is enabled.  Kernel builds with LOCKDEP will be slightly
larger, while !LOCKDEP builds without it will be slightly smaller (the
common case).

Link: https://lkml.kernel.org/r/20241104175257.60853-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20241104175257.60853-2-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/list_lru.h |   18 +++++++++++++++---
 mm/list_lru.c            |    9 +++++----
 mm/workingset.c          |    4 ++--
 3 files changed, 22 insertions(+), 9 deletions(-)

--- a/include/linux/list_lru.h~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/include/linux/list_lru.h
@@ -56,16 +56,28 @@ struct list_lru {
 	bool			memcg_aware;
 	struct xarray		xa;
 #endif
+#ifdef CONFIG_LOCKDEP
+	struct lock_class_key	*key;
+#endif
 };
 
 void list_lru_destroy(struct list_lru *lru);
 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
-		    struct lock_class_key *key, struct shrinker *shrinker);
+		    struct shrinker *shrinker);
 
 #define list_lru_init(lru)				\
-	__list_lru_init((lru), false, NULL, NULL)
+	__list_lru_init((lru), false, NULL)
 #define list_lru_init_memcg(lru, shrinker)		\
-	__list_lru_init((lru), true, NULL, shrinker)
+	__list_lru_init((lru), true, shrinker)
+
+static inline int list_lru_init_memcg_key(struct list_lru *lru, struct shrinker *shrinker,
+					  struct lock_class_key *key)
+{
+#ifdef CONFIG_LOCKDEP
+	lru->key = key;
+#endif
+	return list_lru_init_memcg(lru, shrinker);
+}
 
 int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
 			 gfp_t gfp);
--- a/mm/list_lru.c~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/mm/list_lru.c
@@ -562,8 +562,7 @@ static void memcg_destroy_list_lru(struc
 }
 #endif /* CONFIG_MEMCG */
 
-int __list_lru_init(struct list_lru *lru, bool memcg_aware,
-		    struct lock_class_key *key, struct shrinker *shrinker)
+int __list_lru_init(struct list_lru *lru, bool memcg_aware, struct shrinker *shrinker)
 {
 	int i;
 
@@ -583,8 +582,10 @@ int __list_lru_init(struct list_lru *lru
 
 	for_each_node(i) {
 		spin_lock_init(&lru->node[i].lock);
-		if (key)
-			lockdep_set_class(&lru->node[i].lock, key);
+#ifdef CONFIG_LOCKDEP
+		if (lru->key)
+			lockdep_set_class(&lru->node[i].lock, lru->key);
+#endif
 		init_one_lru(&lru->node[i].lru);
 	}
 
--- a/mm/workingset.c~mm-list_lru-dont-pass-unnecessary-key-parameters
+++ a/mm/workingset.c
@@ -813,8 +813,8 @@ static int __init workingset_init(void)
 	if (!workingset_shadow_shrinker)
 		goto err;
 
-	ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key,
-			      workingset_shadow_shrinker);
+	ret = list_lru_init_memcg_key(&shadow_nodes, workingset_shadow_shrinker,
+				      &shadow_nodes_key);
 	if (ret)
 		goto err_list_lru;
 
_

Patches currently in -mm which might be from kasong@tencent.com are

mm-zswap-avoid-touching-xarray-for-unnecessary-invalidation.patch
mm-list_lru-dont-pass-unnecessary-key-parameters.patch
mm-list_lru-dont-export-list_lru_add.patch
mm-list_lru-code-clean-up-for-reparenting.patch
mm-list_lru-simplify-reparenting-and-initial-allocation.patch
mm-list_lru-split-the-lock-to-per-cgroup-scope.patch
mm-list_lru-simplify-the-list_lru-walk-callback-function.patch