mm: filemap: move sysctl to mm/filemap.c

This moves the filemap related sysctl to mm/filemap.c, and
removes the redundant external variable declaration.

Signed-off-by: Kaixiong Yu <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Joel Granados <[email protected]>

Author: yukaixiong

include/linux/mm.h

@@ -40,8 +40,6 @@ 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);
 

kernel/sysctl.c

@@ -2079,14 +2079,6 @@ static const 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",

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 <linux/fsnotify.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
@@ -1078,6 +1079,19 @@ 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 const 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;
@@ -1086,6 +1100,7 @@ void __init pagecache_init(void)
 		init_waitqueue_head(&folio_wait_table[i]);
 
 	page_writeback_init();
+	register_sysctl_init("vm", filemap_sysctl_table);
 }
 
 /*
@@ -1233,9 +1248,6 @@ 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)
 {