[linux.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_flatmem(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 memory cgroups\n");
	return;
fail:
	printk(KERN_CRIT "allocation of page_cgroup 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);

	if (!section->page_cgroup)
		return NULL;
	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;
		VM_BUG_ON(!slab_is_available());
		base = kmalloc_node(table_size,
				GFP_KERNEL | __GFP_NOWARN, nid);
		if (!base)
			base = vmalloc_node(table_size, nid);
	} 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 memory cgroups\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];

struct swap_cgroup {
	unsigned short		id;
};
#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;

	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, 0 at failure.
 * (Of course, old value can be 0.)
 */
unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
{
	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;
	unsigned short old;

	ctrl = &swap_cgroup_ctrl[type];

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

	return old;
}

/**
 * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
 * @ent: swap entry to be looked up.
 *
 * Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
 */
unsigned short 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;
	unsigned short ret;

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

	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	57	table_size = sizeof(struct page_cgroup) * nr_pages;
ca371c0d KH	58
	59	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
	60	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
	61	if (!base)
52d4b9ac KH	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
ca371c0d	72	void __init page_cgroup_init_flatmem(void)
52d4b9ac KH	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);
8ca739e3 RD	86	printk(KERN_INFO "please try 'cgroup_disable=memory' option if you"
8ca739e3 RD	87	" don't want memory cgroups\n");
52d4b9ac KH	88	return;
52d4b9ac KH	89	fail:
8ca739e3 RD	90	printk(KERN_CRIT "allocation of page_cgroup failed.\n");
8ca739e3 RD	91	printk(KERN_CRIT "please try 'cgroup_disable=memory' boot option\n");
52d4b9ac KH	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
d69b042f BS	102	if (!section->page_cgroup)
d69b042f BS	103	return NULL;
52d4b9ac KH	104	return section->page_cgroup + pfn;
	105	}
	106
31168481	107	/* __alloc_bootmem...() is protected by !slab_available() */
feb16694	108	static int __init_refok init_section_page_cgroup(unsigned long pfn)
52d4b9ac	109	{
0753b0ef	110	struct mem_section *section = __pfn_to_section(pfn);
52d4b9ac KH	111	struct page_cgroup base, pc;
	112	unsigned long table_size;
	113	int nid, index;
	114
dc19f9db KH	115	if (!section->page_cgroup) {
	116	nid = page_to_nid(pfn_to_page(pfn));
	117	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
ca371c0d KH	118	VM_BUG_ON(!slab_is_available());
	119	base = kmalloc_node(table_size,
	120	GFP_KERNEL \| __GFP_NOWARN, nid);
	121	if (!base)
	122	base = vmalloc_node(table_size, nid);
dc19f9db KH	123	} else {
	124	/*
	125	* We don't have to allocate page_cgroup again, but
	126	* address of memmap may be changed. So, we have to initialize
	127	* again.
	128	*/
	129	base = section->page_cgroup + pfn;
	130	table_size = 0;
	131	/* check address of memmap is changed or not. */
	132	if (base->page == pfn_to_page(pfn))
	133	return 0;
94b6da5a	134	}
52d4b9ac KH	135
	136	if (!base) {
	137	printk(KERN_ERR "page cgroup allocation failure\n");
	138	return -ENOMEM;
	139	}
	140
	141	for (index = 0; index < PAGES_PER_SECTION; index++) {
	142	pc = base + index;
	143	__init_page_cgroup(pc, pfn + index);
	144	}
	145
52d4b9ac KH	146	section->page_cgroup = base - pfn;
	147	total_usage += table_size;
	148	return 0;
	149	}
	150	#ifdef CONFIG_MEMORY_HOTPLUG
	151	void __free_page_cgroup(unsigned long pfn)
	152	{
	153	struct mem_section *ms;
	154	struct page_cgroup *base;
	155
	156	ms = __pfn_to_section(pfn);
	157	if (!ms \|\| !ms->page_cgroup)
	158	return;
	159	base = ms->page_cgroup + pfn;
94b6da5a	160	if (is_vmalloc_addr(base)) {
52d4b9ac	161	vfree(base);
94b6da5a KH	162	ms->page_cgroup = NULL;
	163	} else {
	164	struct page *page = virt_to_page(base);
	165	if (!PageReserved(page)) { /* Is bootmem ? */
	166	kfree(base);
	167	ms->page_cgroup = NULL;
	168	}
	169	}
52d4b9ac KH	170	}
52d4b9ac KH	171
31168481	172	int __meminit online_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	173	unsigned long nr_pages,
	174	int nid)
	175	{
	176	unsigned long start, end, pfn;
	177	int fail = 0;
	178
33c5d3d6	179	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	180	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	181
	182	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
	183	if (!pfn_present(pfn))
	184	continue;
	185	fail = init_section_page_cgroup(pfn);
	186	}
	187	if (!fail)
	188	return 0;
	189
	190	/* rollback */
	191	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	192	__free_page_cgroup(pfn);
	193
	194	return -ENOMEM;
	195	}
	196
31168481	197	int __meminit offline_page_cgroup(unsigned long start_pfn,
52d4b9ac KH	198	unsigned long nr_pages, int nid)
	199	{
	200	unsigned long start, end, pfn;
	201
33c5d3d6	202	start = start_pfn & ~(PAGES_PER_SECTION - 1);
52d4b9ac KH	203	end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION);
	204
	205	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	206	__free_page_cgroup(pfn);
	207	return 0;
	208
	209	}
	210
31168481	211	static int __meminit page_cgroup_callback(struct notifier_block *self,
52d4b9ac KH	212	unsigned long action, void *arg)
	213	{
	214	struct memory_notify *mn = arg;
	215	int ret = 0;
	216	switch (action) {
	217	case MEM_GOING_ONLINE:
	218	ret = online_page_cgroup(mn->start_pfn,
	219	mn->nr_pages, mn->status_change_nid);
	220	break;
52d4b9ac KH	221	case MEM_OFFLINE:
	222	offline_page_cgroup(mn->start_pfn,
	223	mn->nr_pages, mn->status_change_nid);
	224	break;
dc19f9db	225	case MEM_CANCEL_ONLINE:
52d4b9ac KH	226	case MEM_GOING_OFFLINE:
	227	break;
	228	case MEM_ONLINE:
	229	case MEM_CANCEL_OFFLINE:
	230	break;
	231	}
dc19f9db KH	232
	233	if (ret)
	234	ret = notifier_from_errno(ret);
	235	else
	236	ret = NOTIFY_OK;
	237
52d4b9ac KH	238	return ret;
	239	}
	240
	241	#endif
	242
	243	void __init page_cgroup_init(void)
	244	{
	245	unsigned long pfn;
	246	int fail = 0;
	247
f8d66542	248	if (mem_cgroup_disabled())
94b6da5a KH	249	return;
94b6da5a KH	250
52d4b9ac KH	251	for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
	252	if (!pfn_present(pfn))
	253	continue;
	254	fail = init_section_page_cgroup(pfn);
	255	}
	256	if (fail) {
8ca739e3	257	printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n");
52d4b9ac KH	258	panic("Out of memory");
	259	} else {
	260	hotplug_memory_notifier(page_cgroup_callback, 0);
	261	}
	262	printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage);
8ca739e3 RD	263	printk(KERN_INFO "please try 'cgroup_disable=memory' option if you don't"
8ca739e3 RD	264	" want memory cgroups\n");
52d4b9ac KH	265	}
52d4b9ac KH	266
31168481	267	void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
52d4b9ac KH	268	{
	269	return;
	270	}
	271
	272	#endif
27a7faa0 KH	273
	274
	275	#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
	276
	277	static DEFINE_MUTEX(swap_cgroup_mutex);
	278	struct swap_cgroup_ctrl {
	279	struct page **map;
	280	unsigned long length;
	281	};
	282
	283	struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
	284
27a7faa0	285	struct swap_cgroup {
a3b2d692	286	unsigned short id;
27a7faa0 KH	287	};
	288	#define SC_PER_PAGE (PAGE_SIZE/sizeof(struct swap_cgroup))
	289	#define SC_POS_MASK (SC_PER_PAGE - 1)
	290
	291	/*
	292	* SwapCgroup implements "lookup" and "exchange" operations.
	293	* In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
	294	* against SwapCache. At swap_free(), this is accessed directly from swap.
	295	*
	296	* This means,
	297	* - we have no race in "exchange" when we're accessed via SwapCache because
	298	* SwapCache(and its swp_entry) is under lock.
	299	* - When called via swap_free(), there is no user of this entry and no race.
	300	* Then, we don't need lock around "exchange".
	301	*
	302	* TODO: we can push these buffers out to HIGHMEM.
	303	*/
	304
	305	/*
	306	* allocate buffer for swap_cgroup.
	307	*/
	308	static int swap_cgroup_prepare(int type)
	309	{
	310	struct page *page;
	311	struct swap_cgroup_ctrl *ctrl;
	312	unsigned long idx, max;
	313
27a7faa0 KH	314	ctrl = &swap_cgroup_ctrl[type];
	315
	316	for (idx = 0; idx < ctrl->length; idx++) {
	317	page = alloc_page(GFP_KERNEL \| __GFP_ZERO);
	318	if (!page)
	319	goto not_enough_page;
	320	ctrl->map[idx] = page;
	321	}
	322	return 0;
	323	not_enough_page:
	324	max = idx;
	325	for (idx = 0; idx < max; idx++)
	326	__free_page(ctrl->map[idx]);
	327
	328	return -ENOMEM;
	329	}
	330
	331	/**
	332	* swap_cgroup_record - record mem_cgroup for this swp_entry.
	333	* @ent: swap entry to be recorded into
	334	* @mem: mem_cgroup to be recorded
	335	*
a3b2d692 KH	336	* Returns old value at success, 0 at failure.
a3b2d692 KH	337	* (Of course, old value can be 0.)
27a7faa0	338	*/
a3b2d692	339	unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
27a7faa0 KH	340	{
	341	int type = swp_type(ent);
	342	unsigned long offset = swp_offset(ent);
	343	unsigned long idx = offset / SC_PER_PAGE;
	344	unsigned long pos = offset & SC_POS_MASK;
	345	struct swap_cgroup_ctrl *ctrl;
	346	struct page *mappage;
	347	struct swap_cgroup *sc;
a3b2d692	348	unsigned short old;
27a7faa0	349
27a7faa0 KH	350	ctrl = &swap_cgroup_ctrl[type];
	351
	352	mappage = ctrl->map[idx];
	353	sc = page_address(mappage);
	354	sc += pos;
a3b2d692 KH	355	old = sc->id;
a3b2d692 KH	356	sc->id = id;
27a7faa0 KH	357
	358	return old;
	359	}
	360
	361	/**
	362	* lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
	363	* @ent: swap entry to be looked up.
	364	*
a3b2d692	365	* Returns CSS ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)
27a7faa0	366	*/
a3b2d692	367	unsigned short lookup_swap_cgroup(swp_entry_t ent)
27a7faa0 KH	368	{
	369	int type = swp_type(ent);
	370	unsigned long offset = swp_offset(ent);
	371	unsigned long idx = offset / SC_PER_PAGE;
	372	unsigned long pos = offset & SC_POS_MASK;
	373	struct swap_cgroup_ctrl *ctrl;
	374	struct page *mappage;
	375	struct swap_cgroup *sc;
a3b2d692	376	unsigned short ret;
27a7faa0	377
27a7faa0 KH	378	ctrl = &swap_cgroup_ctrl[type];
	379	mappage = ctrl->map[idx];
	380	sc = page_address(mappage);
	381	sc += pos;
a3b2d692	382	ret = sc->id;
27a7faa0 KH	383	return ret;
	384	}
	385
	386	int swap_cgroup_swapon(int type, unsigned long max_pages)
	387	{
	388	void *array;
	389	unsigned long array_size;
	390	unsigned long length;
	391	struct swap_cgroup_ctrl *ctrl;
	392
	393	if (!do_swap_account)
	394	return 0;
	395
	396	length = ((max_pages/SC_PER_PAGE) + 1);
	397	array_size = length * sizeof(void *);
	398
	399	array = vmalloc(array_size);
	400	if (!array)
	401	goto nomem;
	402
	403	memset(array, 0, array_size);
	404	ctrl = &swap_cgroup_ctrl[type];
	405	mutex_lock(&swap_cgroup_mutex);
	406	ctrl->length = length;
	407	ctrl->map = array;
	408	if (swap_cgroup_prepare(type)) {
	409	/* memory shortage */
	410	ctrl->map = NULL;
	411	ctrl->length = 0;
	412	vfree(array);
	413	mutex_unlock(&swap_cgroup_mutex);
	414	goto nomem;
	415	}
	416	mutex_unlock(&swap_cgroup_mutex);
	417
27a7faa0 KH	418	return 0;
	419	nomem:
	420	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
	421	printk(KERN_INFO
	422	"swap_cgroup can be disabled by noswapaccount boot option\n");
	423	return -ENOMEM;
	424	}
	425
	426	void swap_cgroup_swapoff(int type)
	427	{
	428	int i;
	429	struct swap_cgroup_ctrl *ctrl;
	430
	431	if (!do_swap_account)
	432	return;
	433
	434	mutex_lock(&swap_cgroup_mutex);
	435	ctrl = &swap_cgroup_ctrl[type];
	436	if (ctrl->map) {
	437	for (i = 0; i < ctrl->length; i++) {
	438	struct page *page = ctrl->map[i];
	439	if (page)
	440	__free_page(page);
	441	}
	442	vfree(ctrl->map);
	443	ctrl->map = NULL;
	444	ctrl->length = 0;
	445	}
	446	mutex_unlock(&swap_cgroup_mutex);
	447	}
	448
	449	#endif