Re: [PATCH v4 -next 06/15] mm: mmap: move sysctl to mm/mmap.c

On 2025/1/2 22:08, Lorenzo Stoakes wrote:
> On Mon, Dec 23, 2024 at 10:15:25PM +0800, Kaixiong Yu wrote:
>> This moves all mmap related sysctls to mm/mmap.c, as part of the
>> kernel/sysctl.c cleaning, also move the variable declaration from
>> kernel/sysctl.c into mm/mmap.c.
>>
>> Signed-off-by: Kaixiong Yu <[email protected]>
>> Reviewed-by: Kees Cook <[email protected]>
> Looks good to me, thanks!
>
> Reviewed-by: Lorenzo Stoakes <[email protected]>

Thanks for your review!

Best ...
>> ---
>> v4:
>>   - const qualify struct ctl_table mmap_table
>> v3:
>>   - change the title
>> v2:
>>   - fix sysctl_max_map_count undeclared issue in mm/nommu.c
>> ---
>> ---
>>   kernel/sysctl.c | 50 +--------------------------------------------
>>   mm/mmap.c       | 54 +++++++++++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 55 insertions(+), 49 deletions(-)
>>
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index aea3482106e0..9c245898f535 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -127,12 +127,6 @@ enum sysctl_writes_mode {
>>
>>   static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
>>   #endif /* CONFIG_PROC_SYSCTL */
>> -
>> -#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
>> -    defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
>> -int sysctl_legacy_va_layout;
>> -#endif
>> -
>>   #endif /* CONFIG_SYSCTL */
>>
>>   /*
>> @@ -2037,16 +2031,7 @@ static struct ctl_table vm_table[] = {
>>   		.extra1		= SYSCTL_ONE,
>>   		.extra2		= SYSCTL_FOUR,
>>   	},
>> -#ifdef CONFIG_MMU
>> -	{
>> -		.procname	= "max_map_count",
>> -		.data		= &sysctl_max_map_count,
>> -		.maxlen		= sizeof(sysctl_max_map_count),
>> -		.mode		= 0644,
>> -		.proc_handler	= proc_dointvec_minmax,
>> -		.extra1		= SYSCTL_ZERO,
>> -	},
>> -#else
>> +#ifndef CONFIG_MMU
>>   	{
>>   		.procname	= "nr_trim_pages",
>>   		.data		= &sysctl_nr_trim_pages,
>> @@ -2064,17 +2049,6 @@ static struct ctl_table vm_table[] = {
>>   		.proc_handler	= proc_dointvec_minmax,
>>   		.extra1		= SYSCTL_ZERO,
>>   	},
> Nitty, but  this bit belongs in mm/nommu.c?
>
>> -#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
>> -    defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
>> -	{
>> -		.procname	= "legacy_va_layout",
>> -		.data		= &sysctl_legacy_va_layout,
>> -		.maxlen		= sizeof(sysctl_legacy_va_layout),
>> -		.mode		= 0644,
>> -		.proc_handler	= proc_dointvec_minmax,
>> -		.extra1		= SYSCTL_ZERO,
>> -	},
>> -#endif
>>   #ifdef CONFIG_MMU
>>   	{
>>   		.procname	= "mmap_min_addr",
>> @@ -2100,28 +2074,6 @@ static struct ctl_table vm_table[] = {
>>   		.extra1		= SYSCTL_ZERO,
>>   	},
>>   #endif
>> -#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
>> -	{
>> -		.procname	= "mmap_rnd_bits",
>> -		.data		= &mmap_rnd_bits,
>> -		.maxlen		= sizeof(mmap_rnd_bits),
>> -		.mode		= 0600,
>> -		.proc_handler	= proc_dointvec_minmax,
>> -		.extra1		= (void *)&mmap_rnd_bits_min,
>> -		.extra2		= (void *)&mmap_rnd_bits_max,
>> -	},
>> -#endif
>> -#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
>> -	{
>> -		.procname	= "mmap_rnd_compat_bits",
>> -		.data		= &mmap_rnd_compat_bits,
>> -		.maxlen		= sizeof(mmap_rnd_compat_bits),
>> -		.mode		= 0600,
>> -		.proc_handler	= proc_dointvec_minmax,
>> -		.extra1		= (void *)&mmap_rnd_compat_bits_min,
>> -		.extra2		= (void *)&mmap_rnd_compat_bits_max,
>> -	},
>> -#endif
>>   };
>>
>>   int __init sysctl_init_bases(void)
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index aef835984b1c..cc579aafd7ba 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -1603,6 +1603,57 @@ struct vm_area_struct *_install_special_mapping(
>>   					&special_mapping_vmops);
>>   }
>>
>> +#ifdef CONFIG_SYSCTL
>> +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
>> +		defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
>> +int sysctl_legacy_va_layout;
>> +#endif
>> +
>> +static const struct ctl_table mmap_table[] = {
>> +		{
>> +				.procname       = "max_map_count",
>> +				.data           = &sysctl_max_map_count,
>> +				.maxlen         = sizeof(sysctl_max_map_count),
>> +				.mode           = 0644,
>> +				.proc_handler   = proc_dointvec_minmax,
>> +				.extra1         = SYSCTL_ZERO,
>> +		},
>> +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
>> +		defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
>> +		{
>> +				.procname       = "legacy_va_layout",
>> +				.data           = &sysctl_legacy_va_layout,
>> +				.maxlen         = sizeof(sysctl_legacy_va_layout),
>> +				.mode           = 0644,
>> +				.proc_handler   = proc_dointvec_minmax,
>> +				.extra1         = SYSCTL_ZERO,
>> +		},
>> +#endif
>> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
>> +		{
>> +				.procname       = "mmap_rnd_bits",
>> +				.data           = &mmap_rnd_bits,
>> +				.maxlen         = sizeof(mmap_rnd_bits),
>> +				.mode           = 0600,
>> +				.proc_handler   = proc_dointvec_minmax,
>> +				.extra1         = (void *)&mmap_rnd_bits_min,
>> +				.extra2         = (void *)&mmap_rnd_bits_max,
>> +		},
>> +#endif
>> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
>> +		{
>> +				.procname       = "mmap_rnd_compat_bits",
>> +				.data           = &mmap_rnd_compat_bits,
>> +				.maxlen         = sizeof(mmap_rnd_compat_bits),
>> +				.mode           = 0600,
>> +				.proc_handler   = proc_dointvec_minmax,
>> +				.extra1         = (void *)&mmap_rnd_compat_bits_min,
>> +				.extra2         = (void *)&mmap_rnd_compat_bits_max,
>> +		},
>> +#endif
>> +};
>> +#endif /* CONFIG_SYSCTL */
>> +
>>   /*
>>    * initialise the percpu counter for VM
>>    */
>> @@ -1612,6 +1663,9 @@ void __init mmap_init(void)
>>
>>   	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
>>   	VM_BUG_ON(ret);
>> +#ifdef CONFIG_SYSCTL
>> +	register_sysctl_init("vm", mmap_table);
>> +#endif
>>   }
>>
>>   /*
>> --
>> 2.34.1
>>
> .
>