[net-next-2.6.git] / mm / page_cgroup.c

#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/bit_spinlock.h>
#include <linux/page_cgroup.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/cgroup.h>
#include <linux/swapops.h>

static void __meminit
__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
{
	pc->flags = 0;
	pc->mem_cgroup = NULL;
	pc->page = pfn_to_page(pfn);
	INIT_LIST_HEAD(&pc->lru);
}
static unsigned long total_usage;

#if !defined(CONFIG_SPARSEMEM)


void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
	pgdat->node_page_cgroup = NULL;
}

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	unsigned long offset;
	struct page_cgroup *base;

	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
	if (unlikely(!base))
		return NULL;

	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
	return base + offset;
}

static int __init alloc_node_page_cgroup(int nid)
{
	struct page_cgroup *base, *pc;
	unsigned long table_size;
	unsigned long start_pfn, nr_pages, index;

	start_pfn = NODE_DATA(nid)->node_start_pfn;
	nr_pages = NODE_DATA(nid)->node_spanned_pages;

	if (!nr_pages)
		return 0;

	table_size = sizeof(struct page_cgroup) * nr_pages;

	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
	if (!base)
		return -ENOMEM;
	for (index = 0; index < nr_pages; index++) {
		pc = base + index;
		__init_page_cgroup(pc, start_pfn + index);
	}
	NODE_DATA(nid)->node_page_cgroup = base;
	total_usage += table_size;
	return 0;
}

void __init page_cgroup_init(void)
{

	int nid, fail;

	if (mem_cgroup_disabled())
		return;

	for_each_online_node(nid)  {
		fail = alloc_node_page_cgroup(nid);
		if (fail)
			goto fail;
	}
	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
	printk(KERN_INFO "please try cgroup_disable=memory option if you"
	" don't want\n");
	return;
fail:
	printk(KERN_CRIT "allocation of page_cgroup was failed.\n");
	printk(KERN_CRIT "please try cgroup_disable=memory boot option\n");
	panic("Out of memory");
}

#else /* CONFIG_FLAT_NODE_MEM_MAP */

struct page_cgroup *lookup_page_cgroup(struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	struct mem_section *section = __pfn_to_section(pfn);

	return section->page_cgroup + pfn;
}

/* __alloc_bootmem...() is protected by !slab_available() */
static int __init_refok init_section_page_cgroup(unsigned long pfn)
{
	struct mem_section *section = __pfn_to_section(pfn);
	struct page_cgroup *base, *pc;
	unsigned long table_size;
	int nid, index;

	if (!section->page_cgroup) {
		nid = page_to_nid(pfn_to_page(pfn));
		table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
		if (slab_is_available()) {
			base = kmalloc_node(table_size,
					GFP_KERNEL | __GFP_NOWARN, nid);
			if (!base)
				base = vmalloc_node(table_size, nid);
		} else {
			base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
				table_size,
				PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
		}
	} else {
		/*
 		 * We don't have to allocate page_cgroup again, but
		 * address of memmap may be changed. So, we have to initialize
		 * again.
		 */
		base = section->page_cgroup + pfn;
		table_size = 0;
		/* check address of memmap is changed or not. */
		if (base->page == pfn_to_page(pfn))
			return 0;
	}

	if (!base) {
		printk(KERN_ERR "page cgroup allocation failure\n");
		return -ENOMEM;
	}

	for (index = 0; index < PAGES_PER_SECTION; index++) {
		pc = base + index;
		__init_page_cgroup(pc, pfn + index);
	}

	section->page_cgroup = base - pfn;
	total_usage += table_size;
	return 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
void __free_page_cgroup(unsigned long pfn)
{
	struct mem_section *ms;
	struct page_cgroup *base;

	ms = __pfn_to_section(pfn);
	if (!ms || !ms->page_cgroup)
		return;
	base = ms->page_cgroup + pfn;
	if (is_vmalloc_addr(base)) {
		vfree(base);
		ms->page_cgroup = NULL;
	} else {
		struct page *page = virt_to_page(base);
		if (!PageReserved(page)) { /* Is bootmem ? */
			kfree(base);
			ms->page_cgroup = NULL;
		}
	}
}

int __meminit online_page_cgroup(unsigned long start_pfn,
			unsigned long nr_pages,
			int nid)
{
	unsigned long start, end, pfn;
	int fail = 0;

	start = start_pfn & ~(PAGES_PER_SECTION - 1);
	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);

	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
		if (!pfn_present(pfn))
			continue;
		fail = init_section_page_cgroup(pfn);
	}
	if (!fail)
		return 0;

	/* rollback */
	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
		__free_page_cgroup(pfn);

	return -ENOMEM;
}

int __meminit offline_page_cgroup(unsigned long start_pfn,
		unsigned long nr_pages, int nid)
{
	unsigned long start, end, pfn;

	start = start_pfn & ~(PAGES_PER_SECTION - 1);
	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);

	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
		__free_page_cgroup(pfn);
	return 0;

}

static int __meminit page_cgroup_callback(struct notifier_block *self,
			       unsigned long action, void *arg)
{
	struct memory_notify *mn = arg;
	int ret = 0;
	switch (action) {
	case MEM_GOING_ONLINE:
		ret = online_page_cgroup(mn->start_pfn,
				   mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_OFFLINE:
		offline_page_cgroup(mn->start_pfn,
				mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_CANCEL_ONLINE:
	case MEM_GOING_OFFLINE:
		break;
	case MEM_ONLINE:
	case MEM_CANCEL_OFFLINE:
		break;
	}

	if (ret)
		ret = notifier_from_errno(ret);
	else
		ret = NOTIFY_OK;

	return ret;
}

#endif

void __init page_cgroup_init(void)
{
	unsigned long pfn;
	int fail = 0;

	if (mem_cgroup_disabled())
		return;

	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
		if (!pfn_present(pfn))
			continue;
		fail = init_section_page_cgroup(pfn);
	}
	if (fail) {
		printk(KERN_CRIT "try cgroup_disable=memory boot option\n");
		panic("Out of memory");
	} else {
		hotplug_memory_notifier(page_cgroup_callback, 0);
	}
	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
	printk(KERN_INFO "please try cgroup_disable=memory option if you don't"
	" want\n");
}

void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
{
	return;
}

#endif


#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP

static DEFINE_MUTEX(swap_cgroup_mutex);
struct swap_cgroup_ctrl {
	struct page **map;
	unsigned long length;
};

struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];

/*
 * This 8bytes seems big..maybe we can reduce this when we can use "id" for
 * cgroup rather than pointer.
 */
struct swap_cgroup {
	struct mem_cgroup	*val;
};
#define SC_PER_PAGE	(PAGE_SIZE/sizeof(struct swap_cgroup))
#define SC_POS_MASK	(SC_PER_PAGE - 1)

/*
 * SwapCgroup implements "lookup" and "exchange" operations.
 * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
 * against SwapCache. At swap_free(), this is accessed directly from swap.
 *
 * This means,
 *  - we have no race in "exchange" when we're accessed via SwapCache because
 *    SwapCache(and its swp_entry) is under lock.
 *  - When called via swap_free(), there is no user of this entry and no race.
 * Then, we don't need lock around "exchange".
 *
 * TODO: we can push these buffers out to HIGHMEM.
 */

/*
 * allocate buffer for swap_cgroup.
 */
static int swap_cgroup_prepare(int type)
{
	struct page *page;
	struct swap_cgroup_ctrl *ctrl;
	unsigned long idx, max;

	if (!do_swap_account)
		return 0;
	ctrl = &swap_cgroup_ctrl[type];

	for (idx = 0; idx < ctrl->length; idx++) {
		page = alloc_page(GFP_KERNEL | __GFP_ZERO);
		if (!page)
			goto not_enough_page;
		ctrl->map[idx] = page;
	}
	return 0;
not_enough_page:
	max = idx;
	for (idx = 0; idx < max; idx++)
		__free_page(ctrl->map[idx]);

	return -ENOMEM;
}

/**
 * swap_cgroup_record - record mem_cgroup for this swp_entry.
 * @ent: swap entry to be recorded into
 * @mem: mem_cgroup to be recorded
 *
 * Returns old value at success, NULL at failure.
 * (Of course, old value can be NULL.)
 */
struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem)
{
	int type = swp_type(ent);
	unsigned long offset = swp_offset(ent);
	unsigned long idx = offset / SC_PER_PAGE;
	unsigned long pos = offset & SC_POS_MASK;
	struct swap_cgroup_ctrl *ctrl;
	struct page *mappage;
	struct swap_cgroup *sc;
	struct mem_cgroup *old;

	if (!do_swap_account)
		return NULL;

	ctrl = &swap_cgroup_ctrl[type];

	mappage = ctrl->map[idx];
	sc = page_address(mappage);
	sc += pos;
	old = sc->val;
	sc->val = mem;

	return old;
}

/**
 * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
 * @ent: swap entry to be looked up.
 *
 * Returns pointer to mem_cgroup at success. NULL at failure.
 */
struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
{
	int type = swp_type(ent);
	unsigned long offset = swp_offset(ent);
	unsigned long idx = offset / SC_PER_PAGE;
	unsigned long pos = offset & SC_POS_MASK;
	struct swap_cgroup_ctrl *ctrl;
	struct page *mappage;
	struct swap_cgroup *sc;
	struct mem_cgroup *ret;

	if (!do_swap_account)
		return NULL;

	ctrl = &swap_cgroup_ctrl[type];
	mappage = ctrl->map[idx];
	sc = page_address(mappage);
	sc += pos;
	ret = sc->val;
	return ret;
}

int swap_cgroup_swapon(int type, unsigned long max_pages)
{
	void *array;
	unsigned long array_size;
	unsigned long length;
	struct swap_cgroup_ctrl *ctrl;

	if (!do_swap_account)
		return 0;

	length = ((max_pages/SC_PER_PAGE) + 1);
	array_size = length * sizeof(void *);

	array = vmalloc(array_size);
	if (!array)
		goto nomem;

	memset(array, 0, array_size);
	ctrl = &swap_cgroup_ctrl[type];
	mutex_lock(&swap_cgroup_mutex);
	ctrl->length = length;
	ctrl->map = array;
	if (swap_cgroup_prepare(type)) {
		/* memory shortage */
		ctrl->map = NULL;
		ctrl->length = 0;
		vfree(array);
		mutex_unlock(&swap_cgroup_mutex);
		goto nomem;
	}
	mutex_unlock(&swap_cgroup_mutex);

	printk(KERN_INFO
		"swap_cgroup: uses %ld bytes of vmalloc for pointer array space"
		" and %ld bytes to hold mem_cgroup pointers on swap\n",
		array_size, length * PAGE_SIZE);
	printk(KERN_INFO
	"swap_cgroup can be disabled by noswapaccount boot option.\n");

	return 0;
nomem:
	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
	printk(KERN_INFO
		"swap_cgroup can be disabled by noswapaccount boot option\n");
	return -ENOMEM;
}

void swap_cgroup_swapoff(int type)
{
	int i;
	struct swap_cgroup_ctrl *ctrl;

	if (!do_swap_account)
		return;

	mutex_lock(&swap_cgroup_mutex);
	ctrl = &swap_cgroup_ctrl[type];
	if (ctrl->map) {
		for (i = 0; i < ctrl->length; i++) {
			struct page *page = ctrl->map[i];
			if (page)
				__free_page(page);
		}
		vfree(ctrl->map);
		ctrl->map = NULL;
		ctrl->length = 0;
	}
	mutex_unlock(&swap_cgroup_mutex);
}

#endif
Commit	Line	Data
52d4b9ac KH	1	#include <linux/mm.h>
	2	#include <linux/mmzone.h>
	3	#include <linux/bootmem.h>
	4	#include <linux/bit_spinlock.h>
	5	#include <linux/page_cgroup.h>
	6	#include <linux/hash.h>
94b6da5a	7	#include <linux/slab.h>
52d4b9ac	8	#include <linux/memory.h>
4c821042	9	#include <linux/vmalloc.h>
94b6da5a	10	#include <linux/cgroup.h>
27a7faa0	11	#include <linux/swapops.h>
52d4b9ac KH	12
	13	static void __meminit
	14	__init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
	15	{
	16	pc->flags = 0;
	17	pc->mem_cgroup = NULL;
	18	pc->page = pfn_to_page(pfn);
08e552c6	19	INIT_LIST_HEAD(&pc->lru);
52d4b9ac KH	20	}
	21	static unsigned long total_usage;
	22
	23	#if !defined(CONFIG_SPARSEMEM)
	24
	25
31168481	26	void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
52d4b9ac KH	27	{
	28	pgdat->node_page_cgroup = NULL;
	29	}
	30
	31	struct page_cgroup lookup_page_cgroup(struct page page)
	32	{
	33	unsigned long pfn = page_to_pfn(page);
	34	unsigned long offset;
	35	struct page_cgroup *base;
	36
	37	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;
	38	if (unlikely(!base))
	39	return NULL;
	40
	41	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
	42	return base + offset;
	43	}
	44
	45	static int __init alloc_node_page_cgroup(int nid)
	46	{
	47	struct page_cgroup base, pc;
	48	unsigned long table_size;
	49	unsigned long start_pfn, nr_pages, index;
	50
	51	start_pfn = NODE_DATA(nid)->node_start_pfn;
	52	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	53
653d22c0 KH	54	if (!nr_pages)
	55	return 0;
	56
52d4b9ac KH	57	table_size = sizeof(struct page_cgroup) * nr_pages;
	58
	59	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
	60	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
	61	if (!base)
	62	return -ENOMEM;
	63	for (index = 0; index < nr_pages; index++) {
	64	pc = base + index;
	65	__init_page_cgroup(pc, start_pfn + index);
	66	}
	67	NODE_DATA(nid)->node_page_cgroup = base;
	68	total_usage += table_size;
	69	return 0;
	70	}
	71
	72	void __init page_cgroup_init(void)
	73	{
	74
	75	int nid, fail;
	76
f8d66542	77	if (mem_cgroup_disabled())
94b6da5a KH	78	return;
94b6da5a KH	79
52d4b9ac KH	80	for_each_online_node(nid) {
	81	fail = alloc_node_page_cgroup(nid);
	82	if (fail)
	83	goto fail;
	84	}
	85	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
	86	printk(KERN_INFO "please try cgroup_disable=memory option if you"
	87	" don't want\n");
	88	return;
	89	fail:
	90	printk(KERN_CRIT "allocation of page_cgroup was failed.\n");
	91	printk(KERN_CRIT "please try cgroup_disable=memory boot option\n");
	92	panic("Out of memory");
	93	}
	94
	95	#else /* CONFIG_FLAT_NODE_MEM_MAP */
	96
	97	struct page_cgroup lookup_page_cgroup(struct page page)
	98	{
	99	unsigned long pfn = page_to_pfn(page);
	100	struct mem_section *section = __pfn_to_section(pfn);
	101
	102	return section->page_cgroup + pfn;
	103	}
	104
31168481	105	/* __alloc_bootmem...() is protected by !slab_available() */
feb16694	106	static int __init_refok init_section_page_cgroup(unsigned long pfn)
52d4b9ac	107	{
0753b0ef	108	struct mem_section *section = __pfn_to_section(pfn);
52d4b9ac KH	109	struct page_cgroup base, pc;
	110	unsigned long table_size;
	111	int nid, index;
	112
dc19f9db KH	113	if (!section->page_cgroup) {
	114	nid = page_to_nid(pfn_to_page(pfn));
	115	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
	116	if (slab_is_available()) {
2e9c2372 KH	117	base = kmalloc_node(table_size,
2e9c2372 KH	118	GFP_KERNEL \| __GFP_NOWARN, nid);
dc19f9db KH	119	if (!base)
	120	base = vmalloc_node(table_size, nid);
	121	} else {
	122	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
	123	table_size,
94b6da5a	124	PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
dc19f9db KH	125	}
	126	} else {
	127	/*
	128	* We don't have to allocate page_cgroup again, but
	129	* address of memmap may be changed. So, we have to initialize
	130	* again.
	131	*/
	132	base = section->page_cgroup + pfn;
	133	table_size = 0;
	134	/* check address of memmap is changed or not. */
	135	if (base->page == pfn_to_page(pfn))
	136	return 0;
94b6da5a	137	}
52d4b9ac KH	138
	139	if (!base) {
	140	printk(KERN_ERR "page cgroup allocation failure\n");
	141	return -ENOMEM;
	142	}
	143
	144	for (index = 0; index < PAGES_PER_SECTION; index++) {
	145	pc = base + index;
	146	__init_page_cgroup(pc, pfn + index);
	147	}
	148
52d4b9ac KH	149	section->page_cgroup = base - pfn;
	150	total_usage += table_size;
	151	return 0;
	152	}
	153	#ifdef CONFIG_MEMORY_HOTPLUG
	154	void __free_page_cgroup(unsigned long pfn)
	155	{
	156	struct mem_section *ms;
	157	struct page_cgroup *base;
	158
	159	ms = __pfn_to_section(pfn);
	160	if (!ms \|\| !ms->page_cgroup)
	161	return;
	162	base = ms->page_cgroup + pfn;
94b6da5a	163	if (is_vmalloc_addr(base)) {
52d4b9ac	164	vfree(base);
94b6da5a KH	165	ms->page_cgroup = NULL;
	166	} else {
	167	struct page *page = virt_to_page(base);
	168	if (!PageReserved(page)) { /* Is bootmem ? */
	169	kfree(base);
	170	ms->page_cgroup = NULL;
	171	}
	172	}
52d4b9ac KH	173	}
52d4b9ac KH	174
31168481	175	int __meminit online_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	176	unsigned long nr_pages,
	177	int nid)
	178	{
	179	unsigned long start, end, pfn;
	180	int fail = 0;
	181
33c5d3d6	182	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	183	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	184
	185	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
	186	if (!pfn_present(pfn))
	187	continue;
	188	fail = init_section_page_cgroup(pfn);
	189	}
	190	if (!fail)
	191	return 0;
	192
	193	/* rollback */
	194	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	195	__free_page_cgroup(pfn);
	196
	197	return -ENOMEM;
	198	}
	199
31168481	200	int __meminit offline_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	201	unsigned long nr_pages, int nid)
	202	{
	203	unsigned long start, end, pfn;
	204
33c5d3d6	205	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	206	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	207
	208	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	209	__free_page_cgroup(pfn);
	210	return 0;
	211
	212	}
	213
31168481	214	static int __meminit page_cgroup_callback(struct notifier_block *self,
52d4b9ac KH	215	unsigned long action, void *arg)
	216	{
	217	struct memory_notify *mn = arg;
	218	int ret = 0;
	219	switch (action) {
	220	case MEM_GOING_ONLINE:
	221	ret = online_page_cgroup(mn->start_pfn,
	222	mn->nr_pages, mn->status_change_nid);
	223	break;
52d4b9ac KH	224	case MEM_OFFLINE:
	225	offline_page_cgroup(mn->start_pfn,
	226	mn->nr_pages, mn->status_change_nid);
	227	break;
dc19f9db	228	case MEM_CANCEL_ONLINE:
52d4b9ac KH	229	case MEM_GOING_OFFLINE:
	230	break;
	231	case MEM_ONLINE:
	232	case MEM_CANCEL_OFFLINE:
	233	break;
	234	}
dc19f9db KH	235
	236	if (ret)
	237	ret = notifier_from_errno(ret);
	238	else
	239	ret = NOTIFY_OK;
	240
52d4b9ac KH	241	return ret;
	242	}
	243
	244	#endif
	245
	246	void __init page_cgroup_init(void)
	247	{
	248	unsigned long pfn;
	249	int fail = 0;
	250
f8d66542	251	if (mem_cgroup_disabled())
94b6da5a KH	252	return;
94b6da5a KH	253
52d4b9ac KH	254	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
	255	if (!pfn_present(pfn))
	256	continue;
	257	fail = init_section_page_cgroup(pfn);
	258	}
	259	if (fail) {
	260	printk(KERN_CRIT "try cgroup_disable=memory boot option\n");
	261	panic("Out of memory");
	262	} else {
	263	hotplug_memory_notifier(page_cgroup_callback, 0);
	264	}
	265	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
	266	printk(KERN_INFO "please try cgroup_disable=memory option if you don't"
	267	" want\n");
	268	}
	269
31168481	270	void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
52d4b9ac KH	271	{
	272	return;
	273	}
	274
	275	#endif
27a7faa0 KH	276
	277
	278	#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
	279
	280	static DEFINE_MUTEX(swap_cgroup_mutex);
	281	struct swap_cgroup_ctrl {
	282	struct page **map;
	283	unsigned long length;
	284	};
	285
	286	struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
	287
	288	/*
	289	* This 8bytes seems big..maybe we can reduce this when we can use "id" for
	290	* cgroup rather than pointer.
	291	*/
	292	struct swap_cgroup {
	293	struct mem_cgroup *val;
	294	};
	295	#define SC_PER_PAGE (PAGE_SIZE/sizeof(struct swap_cgroup))
	296	#define SC_POS_MASK (SC_PER_PAGE - 1)
	297
	298	/*
	299	* SwapCgroup implements "lookup" and "exchange" operations.
	300	* In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
	301	* against SwapCache. At swap_free(), this is accessed directly from swap.
	302	*
	303	* This means,
	304	* - we have no race in "exchange" when we're accessed via SwapCache because
	305	* SwapCache(and its swp_entry) is under lock.
	306	* - When called via swap_free(), there is no user of this entry and no race.
	307	* Then, we don't need lock around "exchange".
	308	*
	309	* TODO: we can push these buffers out to HIGHMEM.
	310	*/
	311
	312	/*
	313	* allocate buffer for swap_cgroup.
	314	*/
	315	static int swap_cgroup_prepare(int type)
	316	{
	317	struct page *page;
	318	struct swap_cgroup_ctrl *ctrl;
	319	unsigned long idx, max;
	320
	321	if (!do_swap_account)
	322	return 0;
	323	ctrl = &swap_cgroup_ctrl[type];
	324
	325	for (idx = 0; idx < ctrl->length; idx++) {
	326	page = alloc_page(GFP_KERNEL \| __GFP_ZERO);
	327	if (!page)
	328	goto not_enough_page;
	329	ctrl->map[idx] = page;
	330	}
	331	return 0;
	332	not_enough_page:
	333	max = idx;
	334	for (idx = 0; idx < max; idx++)
	335	__free_page(ctrl->map[idx]);
	336
	337	return -ENOMEM;
	338	}
	339
340	/**
341	* swap_cgroup_record - record mem_cgroup for this swp_entry.
342	* @ent: swap entry to be recorded into
343	* @mem: mem_cgroup to be recorded
344	*
345	* Returns old value at success, NULL at failure.
346	* (Of course, old value can be NULL.)
347	*/
348	struct mem_cgroup swap_cgroup_record(swp_entry_t ent, struct mem_cgroup mem)
349	{
350	int type = swp_type(ent);
351	unsigned long offset = swp_offset(ent);
352	unsigned long idx = offset / SC_PER_PAGE;
353	unsigned long pos = offset & SC_POS_MASK;
354	struct swap_cgroup_ctrl *ctrl;
355	struct page *mappage;
356	struct swap_cgroup *sc;
357	struct mem_cgroup *old;
358
359	if (!do_swap_account)
360	return NULL;
361
362	ctrl = &swap_cgroup_ctrl[type];
363
364	mappage = ctrl->map[idx];
365	sc = page_address(mappage);
366	sc += pos;
367	old = sc->val;
368	sc->val = mem;
369
370	return old;
371	}
372
373	/**
374	* lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
375	* @ent: swap entry to be looked up.
376	*
377	* Returns pointer to mem_cgroup at success. NULL at failure.
378	*/
379	struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
380	{
381	int type = swp_type(ent);
382	unsigned long offset = swp_offset(ent);
383	unsigned long idx = offset / SC_PER_PAGE;
384	unsigned long pos = offset & SC_POS_MASK;
385	struct swap_cgroup_ctrl *ctrl;
386	struct page *mappage;
387	struct swap_cgroup *sc;
388	struct mem_cgroup *ret;
389
390	if (!do_swap_account)
391	return NULL;
392
393	ctrl = &swap_cgroup_ctrl[type];
394	mappage = ctrl->map[idx];
395	sc = page_address(mappage);
396	sc += pos;
397	ret = sc->val;
398	return ret;
399	}
400
401	int swap_cgroup_swapon(int type, unsigned long max_pages)
402	{
403	void *array;
404	unsigned long array_size;
405	unsigned long length;
406	struct swap_cgroup_ctrl *ctrl;
407
408	if (!do_swap_account)
409	return 0;
410
411	length = ((max_pages/SC_PER_PAGE) + 1);
412	array_size = length * sizeof(void *);
413
414	array = vmalloc(array_size);
415	if (!array)
416	goto nomem;
417
418	memset(array, 0, array_size);
419	ctrl = &swap_cgroup_ctrl[type];
420	mutex_lock(&swap_cgroup_mutex);
421	ctrl->length = length;
422	ctrl->map = array;
423	if (swap_cgroup_prepare(type)) {
424	/* memory shortage */
425	ctrl->map = NULL;
426	ctrl->length = 0;
427	vfree(array);
428	mutex_unlock(&swap_cgroup_mutex);
429	goto nomem;
430	}
431	mutex_unlock(&swap_cgroup_mutex);
432
433	printk(KERN_INFO
434	"swap_cgroup: uses %ld bytes of vmalloc for pointer array space"
435	" and %ld bytes to hold mem_cgroup pointers on swap\n",
436	array_size, length * PAGE_SIZE);
437	printk(KERN_INFO
438	"swap_cgroup can be disabled by noswapaccount boot option.\n");
439
440	return 0;
441	nomem:
442	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
443	printk(KERN_INFO
444	"swap_cgroup can be disabled by noswapaccount boot option\n");
445	return -ENOMEM;
446	}
447
448	void swap_cgroup_swapoff(int type)
449	{
450	int i;
451	struct swap_cgroup_ctrl *ctrl;
452
453	if (!do_swap_account)
454	return;
455
456	mutex_lock(&swap_cgroup_mutex);
457	ctrl = &swap_cgroup_ctrl[type];
458	if (ctrl->map) {
459	for (i = 0; i < ctrl->length; i++) {
460	struct page *page = ctrl->map[i];
461	if (page)
462	__free_page(page);
463	}
464	vfree(ctrl->map);
465	ctrl->map = NULL;
466	ctrl->length = 0;
467	}
468	mutex_unlock(&swap_cgroup_mutex);
469	}
470
471	#endif