[PATCH v2 -next 02/15] mm: filemap: move sysctl to its own file

[Kaixiong Yu <yukaixiong@xxxxxxxxxx>]

This moves the filemap related sysctl to its own file, and
removes the redundant external variable declaration.

Signed-off-by: Kaixiong Yu <yukaixiong@xxxxxxxxxx>
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
---
 include/linux/mm.h |  2 --
 kernel/sysctl.c    |  8 --------
 mm/filemap.c       | 18 +++++++++++++++---
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a7c74a840249..ca196ba1e2d8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -39,8 +39,6 @@ struct user_struct;
 struct pt_regs;
 struct folio_batch;
 
-extern int sysctl_page_lock_unfairness;
-
 void mm_core_init(void);
 void init_mm_internals(void);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 726b866af57b..2a875b739054 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2089,14 +2089,6 @@ static struct ctl_table vm_table[] = {
 		.extra1		= SYSCTL_ONE,
 		.extra2		= SYSCTL_FOUR,
 	},
-	{
-		.procname	= "page_lock_unfairness",
-		.data		= &sysctl_page_lock_unfairness,
-		.maxlen		= sizeof(sysctl_page_lock_unfairness),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
 #ifdef CONFIG_MMU
 	{
 		.procname	= "max_map_count",
diff --git a/mm/filemap.c b/mm/filemap.c
index 065d130c1c07..98e36e2b7290 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -47,6 +47,7 @@
 #include <linux/splice.h>
 #include <linux/rcupdate_wait.h>
 #include <linux/sched/mm.h>
+#include <linux/sysctl.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -1069,6 +1070,19 @@ static wait_queue_head_t *folio_waitqueue(struct folio *folio)
 	return &folio_wait_table[hash_ptr(folio, PAGE_WAIT_TABLE_BITS)];
 }
 
+/* How many times do we accept lock stealing from under a waiter? */
+static int sysctl_page_lock_unfairness = 5;
+static struct ctl_table filemap_sysctl_table[] = {
+	{
+		.procname	= "page_lock_unfairness",
+		.data		= &sysctl_page_lock_unfairness,
+		.maxlen		= sizeof(sysctl_page_lock_unfairness),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+	}
+};
+
 void __init pagecache_init(void)
 {
 	int i;
@@ -1077,6 +1091,7 @@ void __init pagecache_init(void)
 		init_waitqueue_head(&folio_wait_table[i]);
 
 	page_writeback_init();
+	register_sysctl_init("vm", filemap_sysctl_table);
 }
 
 /*
@@ -1224,9 +1239,6 @@ static inline bool folio_trylock_flag(struct folio *folio, int bit_nr,
 	return true;
 }
 
-/* How many times do we accept lock stealing from under a waiter? */
-int sysctl_page_lock_unfairness = 5;
-
 static inline int folio_wait_bit_common(struct folio *folio, int bit_nr,
 		int state, enum behavior behavior)
 {
-- 
2.25.1