Re: [PATCH v4 -next 08/15] mm: nommu: move sysctl to mm/nommu.c

On Mon, Dec 23, 2024 at 10:15:27PM +0800, Kaixiong Yu wrote:
> 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]>

Looks good to me,

Reviewed-by: Lorenzo Stoakes <[email protected]>

> ---
> v4:
>  - const qualify struct ctl_table nommu_table
> v3:
>  - change the title
> v2:
>  - fix the build error: expected ';' after top level declarator
>  - fix the build error: call to undeclared function 'register_syscall_init',
>    use 'register_sysctl_init' to replace it.
> ---
> ---
>  include/linux/mm.h |  2 --
>  kernel/sysctl.c    | 10 ----------
>  mm/nommu.c         | 15 ++++++++++++++-
>  3 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index b3b87c1dc1e4..9813b5b9c093 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4080,8 +4080,6 @@ 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_PRINTK
>  void mem_dump_obj(void *object);
>  #else
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 62a58e417c40..97f9abffff0f 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2031,16 +2031,6 @@ static 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

Of course later on in the series you do what I asked in a previous commit :P Nice.

>  	{
>  		.procname	= "vfs_cache_pressure",
>  		.data		= &sysctl_vfs_cache_pressure,
> diff --git a/mm/nommu.c b/mm/nommu.c
> index baa79abdaf03..3c32f8b1eb54 100644
> --- a/mm/nommu.c
> +++ b/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);
>  }
>
>  /*
> --
> 2.34.1
>