mm: memory-failure: Move memory failure sysctls to its own file

The sysctl_memory_failure_early_kill and memory_failure_recovery
are only used in memory-failure.c, move them to its own file.
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
[mcgrof: fix by adding empty ctl entry, this caused a crash]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

include/linux/mm.h

@@ -3442,8 +3442,6 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
 extern int memory_failure(unsigned long pfn, int flags);
 extern void memory_failure_queue_kick(int cpu);
 extern int unpoison_memory(unsigned long pfn);
-extern int sysctl_memory_failure_early_kill;
-extern int sysctl_memory_failure_recovery;
 extern void shake_page(struct page *p);
 extern atomic_long_t num_poisoned_pages __read_mostly;
 extern int soft_offline_page(unsigned long pfn, int flags);

kernel/sysctl.c

@@ -2350,26 +2350,6 @@ static struct ctl_table vm_table[] = {
 		.proc_handler	= proc_dointvec,
 		.extra1		= SYSCTL_ZERO,
 	},
-#endif
-#ifdef CONFIG_MEMORY_FAILURE
-	{
-		.procname	= "memory_failure_early_kill",
-		.data		= &sysctl_memory_failure_early_kill,
-		.maxlen		= sizeof(sysctl_memory_failure_early_kill),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-	{
-		.procname	= "memory_failure_recovery",
-		.data		= &sysctl_memory_failure_recovery,
-		.maxlen		= sizeof(sysctl_memory_failure_recovery),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
 #endif
 	{
 		.procname	= "user_reserve_kbytes",

mm/memory-failure.c

@@ -62,13 +62,14 @@
 #include <linux/page-isolation.h>
 #include <linux/pagewalk.h>
 #include <linux/shmem_fs.h>
+#include <linux/sysctl.h>
 #include "swap.h"
 #include "internal.h"
 #include "ras/ras_event.h"
 
-int sysctl_memory_failure_early_kill __read_mostly = 0;
+static int sysctl_memory_failure_early_kill __read_mostly;
 
-int sysctl_memory_failure_recovery __read_mostly = 1;
+static int sysctl_memory_failure_recovery __read_mostly = 1;
 
 atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
@@ -122,6 +123,37 @@ const struct attribute_group memory_failure_attr_group = {
 	.attrs = memory_failure_attr,
 };
 
+#ifdef CONFIG_SYSCTL
+static struct ctl_table memory_failure_table[] = {
+	{
+		.procname	= "memory_failure_early_kill",
+		.data		= &sysctl_memory_failure_early_kill,
+		.maxlen		= sizeof(sysctl_memory_failure_early_kill),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{
+		.procname	= "memory_failure_recovery",
+		.data		= &sysctl_memory_failure_recovery,
+		.maxlen		= sizeof(sysctl_memory_failure_recovery),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{ }
+};
+
+static int __init memory_failure_sysctl_init(void)
+{
+	register_sysctl_init("vm", memory_failure_table);
+	return 0;
+}
+late_initcall(memory_failure_sysctl_init);
+#endif /* CONFIG_SYSCTL */
+
 /*
  * Return values:
  *   1:   the page is dissolved (if needed) and taken off from buddy,