+ mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node.patch added to mm-unstable branch

+ mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: memcg: add cache line padding to mem_cgroup_per_node
has been added to the -mm mm-unstable branch.  Its filename is
     mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node.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: Roman Gushchin <roman.gushchin@linux.dev>
Subject: mm: memcg: add cache line padding to mem_cgroup_per_node
Date: Mon, 1 Jul 2024 18:59:32 +0000

Memcg v1-specific fields serve a buffer function between read-mostly and
update often parts of the mem_cgroup_per_node structure.  If
CONFIG_MEMCG_V1 is not set and these fields are not present, an explicit
cacheline padding is needed.

Link: https://lkml.kernel.org/r/20240701185932.704807-2-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Suggested-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/memcontrol.h |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/include/linux/memcontrol.h~mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node
+++ a/include/linux/memcontrol.h
@@ -95,14 +95,16 @@ struct mem_cgroup_per_node {
 #ifdef CONFIG_MEMCG_V1
 	/*
 	 * Memcg-v1 only stuff in middle as buffer between read mostly fields
-	 * and update often fields to avoid false sharing. Once v1 stuff is
-	 * moved in a separate struct, an explicit padding is needed.
+	 * and update often fields to avoid false sharing. If v1 stuff is
+	 * not present, an explicit padding is needed.
 	 */
 
 	struct rb_node		tree_node;	/* RB tree node */
 	unsigned long		usage_in_excess;/* Set to the value by which */
 						/* the soft limit is exceeded*/
 	bool			on_tree;
+#else
+	CACHELINE_PADDING(_pad1_);
 #endif
 
 	/* Fields which get updated often at the end. */
_

Patches currently in -mm which might be from roman.gushchin@linux.dev are

mm-memcg-introduce-memcontrol-v1c.patch
mm-memcg-move-soft-limit-reclaim-code-to-memcontrol-v1c.patch
mm-memcg-rename-soft-limit-reclaim-related-functions.patch
mm-memcg-move-charge-migration-code-to-memcontrol-v1c.patch
mm-memcg-rename-charge-move-related-functions.patch
mm-memcg-move-legacy-memcg-event-code-into-memcontrol-v1c.patch
mm-memcg-rename-memcg_check_events.patch
mm-memcg-move-cgroup-v1-oom-handling-code-into-memcontrol-v1c.patch
mm-memcg-rename-memcg_oom_recover.patch
mm-memcg-move-cgroup-v1-interface-files-to-memcontrol-v1c.patch
mm-memcg-make-memcg1_update_tree-static.patch
mm-memcg-group-cgroup-v1-memcg-related-declarations.patch
mm-memcg-put-cgroup-v1-related-members-of-task_struct-under-config-option.patch
mm-memcg-put-cgroup-v1-related-members-of-task_struct-under-config-option-fix.patch
maintainers-add-mm-memcontrol-v1c-h-to-the-list-of-maintained-files.patch
mm-memcg-move-memcg_account_kmem-to-memcontrol-v1c.patch
mm-memcg-factor-out-legacy-socket-memory-accounting-code.patch
mm-memcg-guard-cgroup-v1-specific-code-in-mem_cgroup_print_oom_meminfo.patch
mm-memcg-gather-memcg1-specific-fields-initialization-in-memcg1_memcg_init.patch
mm-memcg-guard-memcg1-specific-fields-accesses-in-mm-memcontrolc.patch
mm-memcg-put-memcg1-specific-struct-mem_cgroups-members-under-config_memcg_v1.patch
mm-memcg-guard-memcg1-specific-members-of-struct-mem_cgroup_per_node.patch
mm-memcg-put-struct-task_struct-memcg_in_oom-under-config_memcg_v1.patch
mm-memcg-put-struct-task_struct-in_user_fault-under-config_memcg_v1.patch
mm-memcg-drop-obsolete-cache-line-padding-in-struct-mem_cgroup.patch
mm-memcg-add-cache-line-padding-to-mem_cgroup_per_node.patch