[GitHub/mt8127/android_kernel_alcatel_ttab.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_subsys.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, 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_subsys.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
94b6da5a KH	77	if (mem_cgroup_subsys.disabled)
	78	return;
	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()) {
	117	base = kmalloc_node(table_size, GFP_KERNEL, nid);
	118	if (!base)
	119	base = vmalloc_node(table_size, nid);
	120	} else {
	121	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
	122	table_size,
94b6da5a	123	PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
dc19f9db KH	124	}
	125	} else {
	126	/*
	127	* We don't have to allocate page_cgroup again, but
	128	* address of memmap may be changed. So, we have to initialize
	129	* again.
	130	*/
	131	base = section->page_cgroup + pfn;
	132	table_size = 0;
	133	/* check address of memmap is changed or not. */
	134	if (base->page == pfn_to_page(pfn))
	135	return 0;
94b6da5a	136	}
52d4b9ac KH	137
	138	if (!base) {
	139	printk(KERN_ERR "page cgroup allocation failure\n");
	140	return -ENOMEM;
	141	}
	142
	143	for (index = 0; index < PAGES_PER_SECTION; index++) {
	144	pc = base + index;
	145	__init_page_cgroup(pc, pfn + index);
	146	}
	147
52d4b9ac KH	148	section->page_cgroup = base - pfn;
	149	total_usage += table_size;
	150	return 0;
	151	}
	152	#ifdef CONFIG_MEMORY_HOTPLUG
	153	void __free_page_cgroup(unsigned long pfn)
	154	{
	155	struct mem_section *ms;
	156	struct page_cgroup *base;
	157
	158	ms = __pfn_to_section(pfn);
	159	if (!ms \|\| !ms->page_cgroup)
	160	return;
	161	base = ms->page_cgroup + pfn;
94b6da5a	162	if (is_vmalloc_addr(base)) {
52d4b9ac	163	vfree(base);
94b6da5a KH	164	ms->page_cgroup = NULL;
	165	} else {
	166	struct page *page = virt_to_page(base);
	167	if (!PageReserved(page)) { /* Is bootmem ? */
	168	kfree(base);
	169	ms->page_cgroup = NULL;
	170	}
	171	}
52d4b9ac KH	172	}
52d4b9ac KH	173
31168481	174	int __meminit online_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	175	unsigned long nr_pages,
	176	int nid)
	177	{
	178	unsigned long start, end, pfn;
	179	int fail = 0;
	180
33c5d3d6	181	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	182	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	183
	184	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
	185	if (!pfn_present(pfn))
	186	continue;
	187	fail = init_section_page_cgroup(pfn);
	188	}
	189	if (!fail)
	190	return 0;
	191
	192	/* rollback */
	193	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	194	__free_page_cgroup(pfn);
	195
	196	return -ENOMEM;
	197	}
	198
31168481	199	int __meminit offline_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	200	unsigned long nr_pages, int nid)
	201	{
	202	unsigned long start, end, pfn;
	203
33c5d3d6	204	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	205	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	206
	207	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	208	__free_page_cgroup(pfn);
	209	return 0;
	210
	211	}
	212
31168481	213	static int __meminit page_cgroup_callback(struct notifier_block *self,
52d4b9ac KH	214	unsigned long action, void *arg)
	215	{
	216	struct memory_notify *mn = arg;
	217	int ret = 0;
	218	switch (action) {
	219	case MEM_GOING_ONLINE:
	220	ret = online_page_cgroup(mn->start_pfn,
	221	mn->nr_pages, mn->status_change_nid);
	222	break;
52d4b9ac KH	223	case MEM_OFFLINE:
	224	offline_page_cgroup(mn->start_pfn,
	225	mn->nr_pages, mn->status_change_nid);
	226	break;
dc19f9db	227	case MEM_CANCEL_ONLINE:
52d4b9ac KH	228	case MEM_GOING_OFFLINE:
	229	break;
	230	case MEM_ONLINE:
	231	case MEM_CANCEL_OFFLINE:
	232	break;
	233	}
dc19f9db KH	234
	235	if (ret)
	236	ret = notifier_from_errno(ret);
	237	else
	238	ret = NOTIFY_OK;
	239
52d4b9ac KH	240	return ret;
	241	}
	242
	243	#endif
	244
	245	void __init page_cgroup_init(void)
	246	{
	247	unsigned long pfn;
	248	int fail = 0;
	249
94b6da5a KH	250	if (mem_cgroup_subsys.disabled)
	251	return;
	252
52d4b9ac KH	253	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
	254	if (!pfn_present(pfn))
	255	continue;
	256	fail = init_section_page_cgroup(pfn);
	257	}
	258	if (fail) {
	259	printk(KERN_CRIT "try cgroup_disable=memory boot option\n");
	260	panic("Out of memory");
	261	} else {
	262	hotplug_memory_notifier(page_cgroup_callback, 0);
	263	}
	264	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
	265	printk(KERN_INFO "please try cgroup_disable=memory option if you don't"
	266	" want\n");
	267	}
	268
31168481	269	void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
52d4b9ac KH	270	{
	271	return;
	272	}
	273
	274	#endif
27a7faa0 KH	275
	276
	277	#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
	278
	279	static DEFINE_MUTEX(swap_cgroup_mutex);
	280	struct swap_cgroup_ctrl {
	281	struct page **map;
	282	unsigned long length;
	283	};
	284
	285	struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
	286
	287	/*
	288	* This 8bytes seems big..maybe we can reduce this when we can use "id" for
	289	* cgroup rather than pointer.
	290	*/
	291	struct swap_cgroup {
	292	struct mem_cgroup *val;
	293	};
	294	#define SC_PER_PAGE (PAGE_SIZE/sizeof(struct swap_cgroup))
	295	#define SC_POS_MASK (SC_PER_PAGE - 1)
	296
	297	/*
	298	* SwapCgroup implements "lookup" and "exchange" operations.
	299	* In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
	300	* against SwapCache. At swap_free(), this is accessed directly from swap.
	301	*
	302	* This means,
	303	* - we have no race in "exchange" when we're accessed via SwapCache because
	304	* SwapCache(and its swp_entry) is under lock.
	305	* - When called via swap_free(), there is no user of this entry and no race.
	306	* Then, we don't need lock around "exchange".
	307	*
	308	* TODO: we can push these buffers out to HIGHMEM.
	309	*/
	310
	311	/*
	312	* allocate buffer for swap_cgroup.
	313	*/
	314	static int swap_cgroup_prepare(int type)
	315	{
	316	struct page *page;
	317	struct swap_cgroup_ctrl *ctrl;
	318	unsigned long idx, max;
	319
	320	if (!do_swap_account)
	321	return 0;
	322	ctrl = &swap_cgroup_ctrl[type];
	323
	324	for (idx = 0; idx < ctrl->length; idx++) {
	325	page = alloc_page(GFP_KERNEL \| __GFP_ZERO);
	326	if (!page)
	327	goto not_enough_page;
	328	ctrl->map[idx] = page;
	329	}
	330	return 0;
	331	not_enough_page:
	332	max = idx;
	333	for (idx = 0; idx < max; idx++)
	334	__free_page(ctrl->map[idx]);
	335
	336	return -ENOMEM;
	337	}
	338
339	/**
340	* swap_cgroup_record - record mem_cgroup for this swp_entry.
341	* @ent: swap entry to be recorded into
342	* @mem: mem_cgroup to be recorded
343	*
344	* Returns old value at success, NULL at failure.
345	* (Of course, old value can be NULL.)
346	*/
347	struct mem_cgroup swap_cgroup_record(swp_entry_t ent, struct mem_cgroup mem)
348	{
349	int type = swp_type(ent);
350	unsigned long offset = swp_offset(ent);
351	unsigned long idx = offset / SC_PER_PAGE;
352	unsigned long pos = offset & SC_POS_MASK;
353	struct swap_cgroup_ctrl *ctrl;
354	struct page *mappage;
355	struct swap_cgroup *sc;
356	struct mem_cgroup *old;
357
358	if (!do_swap_account)
359	return NULL;
360
361	ctrl = &swap_cgroup_ctrl[type];
362
363	mappage = ctrl->map[idx];
364	sc = page_address(mappage);
365	sc += pos;
366	old = sc->val;
367	sc->val = mem;
368
369	return old;
370	}
371
372	/**
373	* lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
374	* @ent: swap entry to be looked up.
375	*
376	* Returns pointer to mem_cgroup at success. NULL at failure.
377	*/
378	struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
379	{
380	int type = swp_type(ent);
381	unsigned long offset = swp_offset(ent);
382	unsigned long idx = offset / SC_PER_PAGE;
383	unsigned long pos = offset & SC_POS_MASK;
384	struct swap_cgroup_ctrl *ctrl;
385	struct page *mappage;
386	struct swap_cgroup *sc;
387	struct mem_cgroup *ret;
388
389	if (!do_swap_account)
390	return NULL;
391
392	ctrl = &swap_cgroup_ctrl[type];
393	mappage = ctrl->map[idx];
394	sc = page_address(mappage);
395	sc += pos;
396	ret = sc->val;
397	return ret;
398	}
399
400	int swap_cgroup_swapon(int type, unsigned long max_pages)
401	{
402	void *array;
403	unsigned long array_size;
404	unsigned long length;
405	struct swap_cgroup_ctrl *ctrl;
406
407	if (!do_swap_account)
408	return 0;
409
410	length = ((max_pages/SC_PER_PAGE) + 1);
411	array_size = length * sizeof(void *);
412
413	array = vmalloc(array_size);
414	if (!array)
415	goto nomem;
416
417	memset(array, 0, array_size);
418	ctrl = &swap_cgroup_ctrl[type];
419	mutex_lock(&swap_cgroup_mutex);
420	ctrl->length = length;
421	ctrl->map = array;
422	if (swap_cgroup_prepare(type)) {
423	/* memory shortage */
424	ctrl->map = NULL;
425	ctrl->length = 0;
426	vfree(array);
427	mutex_unlock(&swap_cgroup_mutex);
428	goto nomem;
429	}
430	mutex_unlock(&swap_cgroup_mutex);
431
432	printk(KERN_INFO
433	"swap_cgroup: uses %ld bytes of vmalloc for pointer array space"
434	" and %ld bytes to hold mem_cgroup pointers on swap\n",
435	array_size, length * PAGE_SIZE);
436	printk(KERN_INFO
437	"swap_cgroup can be disabled by noswapaccount boot option.\n");
438
439	return 0;
440	nomem:
441	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
442	printk(KERN_INFO
443	"swap_cgroup can be disabled by noswapaccount boot option\n");
444	return -ENOMEM;
445	}
446
447	void swap_cgroup_swapoff(int type)
448	{
449	int i;
450	struct swap_cgroup_ctrl *ctrl;
451
452	if (!do_swap_account)
453	return;
454
455	mutex_lock(&swap_cgroup_mutex);
456	ctrl = &swap_cgroup_ctrl[type];
457	if (ctrl->map) {
458	for (i = 0; i < ctrl->length; i++) {
459	struct page *page = ctrl->map[i];
460	if (page)
461	__free_page(page);
462	}
463	vfree(ctrl->map);
464	ctrl->map = NULL;
465	ctrl->length = 0;
466	}
467	mutex_unlock(&swap_cgroup_mutex);
468	}
469
470	#endif