[PATCH v4 -next 03/15] mm: swap: move sysctl to mm/swap.c

The page-cluster belongs to mm/swap.c, move it to mm/swap.c .
Removes the redundant external variable declaration and unneeded
include(linux/swap.h).

Signed-off-by: Kaixiong Yu <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
---
v4:
 - const qualify struct ctl_table swap_sysctl_table
v3:
 - change the title
---
---
 include/linux/mm.h |  2 --
 kernel/sysctl.c    | 10 ----------
 mm/swap.c          | 16 +++++++++++++++-
 mm/swap.h          |  1 +
 4 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dbdf8950d681..8941ba3d9a77 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -76,8 +76,6 @@ static inline void totalram_pages_add(long count)
 }
 
 extern void * high_memory;
-extern int page_cluster;
-extern const int page_cluster_max;
 
 #ifdef CONFIG_SYSCTL
 extern int sysctl_legacy_va_layout;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 23c8db80da5d..ab5d94f07e53 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -21,7 +21,6 @@
 
 #include <linux/module.h>
 #include <linux/mm.h>
-#include <linux/swap.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
 #include <linux/bitmap.h>
@@ -2044,15 +2043,6 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= overcommit_kbytes_handler,
 	},
-	{
-		.procname	= "page-cluster",
-		.data		= &page_cluster,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= (void *)&page_cluster_max,
-	},
 	{
 		.procname	= "dirtytime_expire_seconds",
 		.data		= &dirtytime_expire_interval,
diff --git a/mm/swap.c b/mm/swap.c
index 062c8565b899..d3344123381c 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -45,7 +45,7 @@
 
 /* How many pages do we try to swap or page in/out together? As a power of 2 */
 int page_cluster;
-const int page_cluster_max = 31;
+static const int page_cluster_max = 31;
 
 struct cpu_fbatches {
 	/*
@@ -1072,6 +1072,18 @@ void folio_batch_remove_exceptionals(struct folio_batch *fbatch)
 	fbatch->nr = j;
 }
 
+static const struct ctl_table swap_sysctl_table[] = {
+	{
+		.procname	= "page-cluster",
+		.data		= &page_cluster,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= (void *)&page_cluster_max,
+	}
+};
+
 /*
  * Perform any setup for the swap system
  */
@@ -1088,4 +1100,6 @@ void __init swap_setup(void)
 	 * Right now other parts of the system means that we
 	 * _really_ don't want to cluster much more
 	 */
+
+	register_sysctl_init("vm", swap_sysctl_table);
 }
diff --git a/mm/swap.h b/mm/swap.h
index ad2f121de970..274dcc6219a0 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -3,6 +3,7 @@
 #define _MM_SWAP_H
 
 struct mempolicy;
+extern int page_cluster;
 
 #ifdef CONFIG_SWAP
 #include <linux/swapops.h> /* for swp_offset */
-- 
2.34.1