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

The sysctl_nr_trim_pages belongs to nommu.c, move it to mm/nommu.c
from /kernel/sysctl.c. And remove the useless extern variable declaration
from include/linux/mm.h

Signed-off-by: Kaixiong Yu <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Signed-off-by: Joel Granados <[email protected]>

Author: yukaixiong

include/linux/mm.h

@@ -4066,8 +4066,6 @@ unsigned long wp_shared_mapping_range(struct address_space *mapping,
 				      pgoff_t first_index, pgoff_t nr);
 #endif
 
-extern int sysctl_nr_trim_pages;
-
 #ifdef CONFIG_ANON_VMA_NAME
 int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
 			  unsigned long len_in,

kernel/sysctl.c

@@ -2031,16 +2031,6 @@ static const struct ctl_table vm_table[] = {
 		.extra1		= SYSCTL_ONE,
 		.extra2		= SYSCTL_FOUR,
 	},
-#ifndef CONFIG_MMU
-	{
-		.procname	= "nr_trim_pages",
-		.data		= &sysctl_nr_trim_pages,
-		.maxlen		= sizeof(sysctl_nr_trim_pages),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
-#endif
 	{
 		.procname	= "vfs_cache_pressure",
 		.data		= &sysctl_vfs_cache_pressure,

mm/nommu.c

@@ -48,7 +48,6 @@ struct page *mem_map;
 unsigned long max_mapnr;
 EXPORT_SYMBOL(max_mapnr);
 unsigned long highest_memmap_pfn;
-int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
 int heap_stack_gap = 0;
 
 atomic_long_t mmap_pages_allocated;
@@ -392,6 +391,19 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	return mm->brk = brk;
 }
 
+static int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
+
+static const struct ctl_table nommu_table[] = {
+	{
+		.procname	= "nr_trim_pages",
+		.data		= &sysctl_nr_trim_pages,
+		.maxlen		= sizeof(sysctl_nr_trim_pages),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+	},
+};
+
 /*
  * initialise the percpu counter for VM and region record slabs
  */
@@ -402,6 +414,7 @@ void __init mmap_init(void)
 	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
 	VM_BUG_ON(ret);
 	vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT);
+	register_sysctl_init("vm", nommu_table);
 }
 
 /*