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

[yukaixiong <yukaixiong@xxxxxxxxxx>]

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 <yukaixiong@xxxxxxxxxx>
> > Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
> Looks good to me, thanks!
>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>

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
> .