linux/mm/hugetlb_sysctl.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * HugeTLB sysfs interfaces.
 * (C) Nadia Yvette Chambers, April 2004
 */

#include <linux/sysctl.h>

#include "hugetlb_internal.h"

#ifdef CONFIG_SYSCTL
static int proc_hugetlb_doulongvec_minmax(const struct ctl_table *table, int write,
					  void *buffer, size_t *length,
					  loff_t *ppos, unsigned long *out)
{
	struct ctl_table dup_table;

	/*
	 * In order to avoid races with __do_proc_doulongvec_minmax(), we
	 * can duplicate the @table and alter the duplicate of it.
	 */
	dup_table = *table;
	dup_table.data = out;

	return proc_doulongvec_minmax(&dup_table, write, buffer, length, ppos);
}

static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
			 const struct ctl_table *table, int write,
			 void *buffer, size_t *length, loff_t *ppos)
{
	struct hstate *h = &default_hstate;
	unsigned long tmp = h->max_huge_pages;
	int ret;

	if (!hugepages_supported())
		return -EOPNOTSUPP;

	ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
					     &tmp);
	if (ret)
		goto out;

	if (write)
		ret = __nr_hugepages_store_common(obey_mempolicy, h,
						  NUMA_NO_NODE, tmp, *length);
out:
	return ret;
}

static int hugetlb_sysctl_handler(const struct ctl_table *table, int write,
			  void *buffer, size_t *length, loff_t *ppos)
{

	return hugetlb_sysctl_handler_common(false, table, write,
							buffer, length, ppos);
}

#ifdef CONFIG_NUMA
static int hugetlb_mempolicy_sysctl_handler(const struct ctl_table *table, int write,
			  void *buffer, size_t *length, loff_t *ppos)
{
	return hugetlb_sysctl_handler_common(true, table, write,
							buffer, length, ppos);
}
#endif /* CONFIG_NUMA */

static int hugetlb_overcommit_handler(const struct ctl_table *table, int write,
		void *buffer, size_t *length, loff_t *ppos)
{
	struct hstate *h = &default_hstate;
	unsigned long tmp;
	int ret;

	if (!hugepages_supported())
		return -EOPNOTSUPP;

	tmp = h->nr_overcommit_huge_pages;

	if (write && hstate_is_gigantic_no_runtime(h))
		return -EINVAL;

	ret = proc_hugetlb_doulongvec_minmax(table, write, buffer, length, ppos,
					     &tmp);
	if (ret)
		goto out;

	if (write) {
		spin_lock_irq(&hugetlb_lock);
		h->nr_overcommit_huge_pages = tmp;
		spin_unlock_irq(&hugetlb_lock);
	}
out:
	return ret;
}

static const struct ctl_table hugetlb_table[] = {
	{
		.procname	= "nr_hugepages",
		.data		= NULL,
		.maxlen		= sizeof(unsigned long),
		.mode		= 0644,
		.proc_handler	= hugetlb_sysctl_handler,
	},
#ifdef CONFIG_NUMA
	{
		.procname       = "nr_hugepages_mempolicy",
		.data           = NULL,
		.maxlen         = sizeof(unsigned long),
		.mode           = 0644,
		.proc_handler   = &hugetlb_mempolicy_sysctl_handler,
	},
#endif
	{
		.procname	= "hugetlb_shm_group",
		.data		= &sysctl_hugetlb_shm_group,
		.maxlen		= sizeof(gid_t),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{
		.procname	= "nr_overcommit_hugepages",
		.data		= NULL,
		.maxlen		= sizeof(unsigned long),
		.mode		= 0644,
		.proc_handler	= hugetlb_overcommit_handler,
	},
};

void __init hugetlb_sysctl_init(void)
{
	register_sysctl_init("vm", hugetlb_table);
}
#endif /* CONFIG_SYSCTL */