path: root/mm/hugetlb.c

/*
 * Generic hugetlb support.
 * (C) William Irwin, April 2004
 */
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/sysctl.h>
#include <linux/highmem.h>
#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>

#include <asm/page.h>
#include <asm/pgtable.h>

#include <linux/hugetlb.h>
#include "internal.h"

const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
unsigned long max_huge_pages;
static struct list_head hugepage_freelists[MAX_NUMNODES];
static unsigned int nr_huge_pages_node[MAX_NUMNODES];
static unsigned int free_huge_pages_node[MAX_NUMNODES];
/*
 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
 */
static DEFINE_SPINLOCK(hugetlb_lock);

static void clear_huge_page(struct page *page, unsigned long addr)
{
	int i;

	might_sleep();
	for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
		cond_resched();
		clear_user_highpage(page + i, addr);
	}
}

static void copy_huge_page(struct page *dst, struct page *src,
			   unsigned long addr)
{
	int i;

	might_sleep();
	for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
		cond_resched();
		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE);
	}
}

static void enqueue_huge_page(struct page *page)
{
	int nid = page_to_nid(page);
	list_add(&page->lru, &hugepage_freelists[nid]);
	free_huge_pages++;
	free_huge_pages_node[nid]++;
}

static struct page *dequeue_huge_page(struct vm_area_struct *vma,
				unsigned long address)
{
	int nid = numa_node_id();
	struct page *page = NULL;
	struct zonelist *zonelist = huge_zonelist(vma, address);
	struct zone **z;

	for (z = zonelist->zones; *z; z++) {
		nid = zone_to_nid(*z);
		if (cpuset_zone_allowed_softwall(*z, GFP_HIGHUSER) &&
		    !list_empty(&hugepage_freelists[nid]))
			break;
	}

	if (*z) {
		page = list_entry(hugepage_freelists[nid].next,
				  struct page, lru);
		list_del(&page->lru);
		free_huge_pages--;
		free_huge_pages_node[nid]--;
	}
	return page;
}

static void free_huge_page(struct page *page)
{
	BUG_ON(page_count(page));

	INIT_LIST_HEAD(&page->lru);

	spin_lock(&hugetlb_lock);
	enqueue_huge_page(page);
	spin_unlock(&hugetlb_lock);
}

static int alloc_fresh_huge_page(void)
{
	static int nid = 0;
	struct page *page;
	page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
					HUGETLB_PAGE_ORDER);
	nid = next_node(nid, node_online_map);
	if (nid == MAX_NUMNODES)
		nid = first_node(node_online_map);
	if (page) {
		set_compound_page_dtor(page, free_huge_page);
		spin_lock(&hugetlb_lock);
		nr_huge_pages++;
		nr_huge_pages_node[page_to_nid(page)]++;
		spin_unlock(&hugetlb_lock);
		put_page(page); /* free it into the hugepage allocator */
		return 1;
	}
	return 0;
}

static struct page *alloc_huge_page(struct vm_area_struct *vma,
				    unsigned long addr)
{
	struct page *page;

	spin_lock(&hugetlb_lock);
	if (vma->vm_flags & VM_MAYSHARE)
		resv_huge_pages--;
	else if (free_huge_pages <= resv_huge_pages)
		goto fail;

	page = dequeue_huge_page(vma, addr);
	if (!page)
		goto fail;

	spin_unlock(&hugetlb_lock);
	set_page_refcounted(page);
	return page;

fail:
	spin_unlock(&hugetlb_lock);
	return NULL;
}

static int __init hugetlb_init(void)
{
	unsigned long i;

	if (HPAGE_SHIFT == 0)
		return 0;

	for (i = 0; i < MAX_NUMNODES; ++i)
		INIT_LIST_HEAD(&hugepage_freelists[i]);

	for (i = 0; i < max_huge_pages; ++i) {
		if (!alloc_fresh_huge_page())
			break;
	}
	max_huge_pages = free_huge_pages = nr_huge_pages = i;
	printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
	return 0;
}
module_init(hugetlb_init);

static int __init hugetlb_setup(char *s)
{
	if (sscanf(s, "%lu", &max_huge_pages) <= 0)
		max_huge_pages = 0;
	return 1;
}
__setup("hugepages=", hugetlb_setup);

#ifdef CONFIG_SYSCTL
static void update_and_free_page(struct page *page)
{
	int i;
	nr_huge_pages--;
	nr_huge_pages_node[page_to_nid(page)]--;
	for (i = 0; i <