[linux.git] / mm / page_ext.c

#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/bootmem.h>
#include <linux/page_ext.h>
#include <linux/memory.h>
#include <linux/vmalloc.h>
#include <linux/kmemleak.h>
#include <linux/page_owner.h>
#include <linux/page_idle.h>

/*
 * struct page extension
 *
 * This is the feature to manage memory for extended data per page.
 *
 * Until now, we must modify struct page itself to store extra data per page.
 * This requires rebuilding the kernel and it is really time consuming process.
 * And, sometimes, rebuild is impossible due to third party module dependency.
 * At last, enlarging struct page could cause un-wanted system behaviour change.
 *
 * This feature is intended to overcome above mentioned problems. This feature
 * allocates memory for extended data per page in certain place rather than
 * the struct page itself. This memory can be accessed by the accessor
 * functions provided by this code. During the boot process, it checks whether
 * allocation of huge chunk of memory is needed or not. If not, it avoids
 * allocating memory at all. With this advantage, we can include this feature
 * into the kernel in default and can avoid rebuild and solve related problems.
 *
 * To help these things to work well, there are two callbacks for clients. One
 * is the need callback which is mandatory if user wants to avoid useless
 * memory allocation at boot-time. The other is optional, init callback, which
 * is used to do proper initialization after memory is allocated.
 *
 * The need callback is used to decide whether extended memory allocation is
 * needed or not. Sometimes users want to deactivate some features in this
 * boot and extra memory would be unneccessary. In this case, to avoid
 * allocating huge chunk of memory, each clients represent their need of
 * extra memory through the need callback. If one of the need callbacks
 * returns true, it means that someone needs extra memory so that
 * page extension core should allocates memory for page extension. If
 * none of need callbacks return true, memory isn't needed at all in this boot
 * and page extension core can skip to allocate memory. As result,
 * none of memory is wasted.
 *
 * When need callback returns true, page_ext checks if there is a request for
 * extra memory through size in struct page_ext_operations. If it is non-zero,
 * extra space is allocated for each page_ext entry and offset is returned to
 * user through offset in struct page_ext_operations.
 *
 * The init callback is used to do proper initialization after page extension
 * is completely initialized. In sparse memory system, extra memory is
 * allocated some time later than memmap is allocated. In other words, lifetime
 * of memory for page extension isn't same with memmap for struct page.
 * Therefore, clients can't store extra data until page extension is
 * initialized, even if pages are allocated and used freely. This could
 * cause inadequate state of extra data per page, so, to prevent it, client
 * can utilize this callback to initialize the state of it correctly.
 */

static struct page_ext_operations *page_ext_ops[] = {
	&debug_guardpage_ops,
#ifdef CONFIG_PAGE_POISONING
	&page_poisoning_ops,
#endif
#ifdef CONFIG_PAGE_OWNER
	&page_owner_ops,
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
	&page_idle_ops,
#endif
};

static unsigned long total_usage;
static unsigned long extra_mem;

static bool __init invoke_need_callbacks(void)
{
	int i;
	int entries = ARRAY_SIZE(page_ext_ops);
	bool need = false;

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
			page_ext_ops[i]->offset = sizeof(struct page_ext) +
						extra_mem;
			extra_mem += page_ext_ops[i]->size;
			need = true;
		}
	}

	return need;
}

static void __init invoke_init_callbacks(void)
{
	int i;
	int entries = ARRAY_SIZE(page_ext_ops);

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->init)
			page_ext_ops[i]->init();
	}
}

static unsigned long get_entry_size(void)
{
	return sizeof(struct page_ext) + extra_mem;
}

static inline struct page_ext *get_entry(void *base, unsigned long index)
{
	return base + get_entry_size() * index;
}

#if !defined(CONFIG_SPARSEMEM)


void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
{
	pgdat->node_page_ext = NULL;
}

struct page_ext *lookup_page_ext(struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	unsigned long index;
	struct page_ext *base;

	base = NODE_DATA(page_to_nid(page))->node_page_ext;
#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
	/*
	 * The sanity checks the page allocator does upon freeing a
	 * page can reach here before the page_ext arrays are
	 * allocated when feeding a range of pages to the allocator
	 * for the first time during bootup or memory hotplug.
	 *
	 * This check is also necessary for ensuring page poisoning
	 * works as expected when enabled
	 */
	if (unlikely(!base))
		return NULL;
#endif
	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
					MAX_ORDER_NR_PAGES);
	return get_entry(base, index);
}

static int __init alloc_node_page_ext(int nid)
{
	struct page_ext *base;
	unsigned long table_size;
	unsigned long nr_pages;

	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	if (!nr_pages)
		return 0;

	/*
	 * Need extra space if node range is not aligned with
	 * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
	 * checks buddy's status, range could be out of exact node range.
	 */
	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
		!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
		nr_pages += MAX_ORDER_NR_PAGES;

	table_size = get_entry_size() * nr_pages;

	base = memblock_virt_alloc_try_nid_nopanic(
			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
			BOOTMEM_ALLOC_ACCESSIBLE, nid);
	if (!base)
		return -ENOMEM;
	NODE_DATA(nid)->node_page_ext = base;
	total_usage += table_size;
	return 0;
}

void __init page_ext_init_flatmem(void)
{

	int nid, fail;

	if (!invoke_need_callbacks())
		return;

	for_each_online_node(nid)  {
		fail = alloc_node_page_ext(nid);
		if (fail)
			goto fail;
	}
	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	invoke_init_callbacks();
	return;

fail:
	pr_crit("allocation of page_ext failed.\n");
	panic("Out of memory");
}

#else /* CONFIG_FLAT_NODE_MEM_MAP */

struct page_ext *lookup_page_ext(struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	struct mem_section *section = __pfn_to_section(pfn);
#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
	/*
	 * The sanity checks the page allocator does upon freeing a
	 * page can reach here before the page_ext arrays are
	 * allocated when feeding a range of pages to the allocator
	 * for the first time during bootup or memory hotplug.
	 *
	 * This check is also necessary for ensuring page poisoning
	 * works as expected when enabled
	 */
	if (!section->page_ext)
		return NULL;
#endif
	return get_entry(section->page_ext, pfn);
}

static void *__meminit alloc_page_ext(size_t size, int nid)
{
	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
	void *addr = NULL;

	addr = alloc_pages_exact_nid(nid, size, flags);
	if (addr) {
		kmemleak_alloc(addr, size, 1, flags);
		return addr;
	}

	if (node_state(nid, N_HIGH_MEMORY))
		addr = vzalloc_node(size, nid);
	else
		addr = vzalloc(size);

	return addr;
}

static int __meminit init_section_page_ext(unsigned long pfn, int nid)
{
	struct mem_section *section;
	struct page_ext *base;
	unsigned long table_size;

	section = __pfn_to_section(pfn);

	if (section->page_ext)
		return 0;

	table_size = get_entry_size() * PAGES_PER_SECTION;
	base = alloc_page_ext(table_size, nid);

	/*
	 * The value stored in section->page_ext is (base - pfn)
	 * and it does not point to the memory block allocated above,
	 * causing kmemleak false positives.
	 */
	kmemleak_not_leak(base);

	if (!base) {
		pr_err("page ext allocation failure\n");
		return -ENOMEM;
	}

	/*
	 * The passed "pfn" may not be aligned to SECTION.  For the calculation
	 * we need to apply a mask.
	 */
	pfn &= PAGE_SECTION_MASK;
	section->page_ext = (void *)base - get_entry_size() * pfn;
	total_usage += table_size;
	return 0;
}
#ifdef CONFIG_MEMORY_HOTPLUG
static void free_page_ext(void *addr)
{
	if (is_vmalloc_addr(addr)) {
		vfree(addr);
	} else {
		struct page *page = virt_to_page(addr);
		size_t table_size;

		table_size = get_entry_size() * PAGES_PER_SECTION;

		BUG_ON(PageReserved(page));
		free_pages_exact(addr, table_size);
	}
}

static void __free_page_ext(unsigned long pfn)
{
	struct mem_section *ms;
	struct page_ext *base;

	ms = __pfn_to_section(pfn);
	if (!ms || !ms->page_ext)
		return;
	base = get_entry(ms->page_ext, pfn);
	free_page_ext(base);
	ms->page_ext = NULL;
}

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

	start = SECTION_ALIGN_DOWN(start_pfn);
	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

	if (nid == -1) {
		/*
		 * In this case, "nid" already exists and contains valid memory.
		 * "start_pfn" passed to us is a pfn which is an arg for
		 * online__pages(), and start_pfn should exist.
		 */
		nid = pfn_to_nid(start_pfn);
		VM_BUG_ON(!node_state(nid, N_ONLINE));
	}

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

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

	return -ENOMEM;
}

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

	start = SECTION_ALIGN_DOWN(start_pfn);
	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

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

}

static int __meminit page_ext_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_ext(mn->start_pfn,
				   mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_OFFLINE:
		offline_page_ext(mn->start_pfn,
				mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_CANCEL_ONLINE:
		offline_page_ext(mn->start_pfn,
				mn->nr_pages, mn->status_change_nid);
		break;
	case MEM_GOING_OFFLINE:
		break;
	case MEM_ONLINE:
	case MEM_CANCEL_OFFLINE:
		break;
	}

	return notifier_from_errno(ret);
}

#endif

void __init page_ext_init(void)
{
	unsigned long pfn;
	int nid;

	if (!invoke_need_callbacks())
		return;

	for_each_node_state(nid, N_MEMORY) {
		unsigned long start_pfn, end_pfn;

		start_pfn = node_start_pfn(nid);
		end_pfn = node_end_pfn(nid);
		/*
		 * start_pfn and end_pfn may not be aligned to SECTION and the
		 * page->flags of out of node pages are not initialized.  So we
		 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
		 */
		for (pfn = start_pfn; pfn < end_pfn;
			pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {

			if (!pfn_valid(pfn))
				continue;
			/*
			 * Nodes's pfns can be overlapping.
			 * We know some arch can have a nodes layout such as
			 * -------------pfn-------------->
			 * N0 | N1 | N2 | N0 | N1 | N2|....
			 *
			 * Take into account DEFERRED_STRUCT_PAGE_INIT.
			 */
			if (early_pfn_to_nid(pfn) != nid)
				continue;
			if (init_section_page_ext(pfn, nid))
				goto oom;
		}
	}
	hotplug_memory_notifier(page_ext_callback, 0);
	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	invoke_init_callbacks();
	return;

oom:
	panic("Out of memory");
}

void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
{
}

#endif
Commit	Line	Data
eefa864b JK	1	#include <linux/mm.h>
	2	#include <linux/mmzone.h>
	3	#include <linux/bootmem.h>
	4	#include <linux/page_ext.h>
	5	#include <linux/memory.h>
	6	#include <linux/vmalloc.h>
	7	#include <linux/kmemleak.h>
48c96a36	8	#include <linux/page_owner.h>
33c3fc71	9	#include <linux/page_idle.h>
eefa864b JK	10
	11	/*
	12	* struct page extension
	13	*
	14	* This is the feature to manage memory for extended data per page.
	15	*
	16	* Until now, we must modify struct page itself to store extra data per page.
	17	* This requires rebuilding the kernel and it is really time consuming process.
	18	* And, sometimes, rebuild is impossible due to third party module dependency.
	19	* At last, enlarging struct page could cause un-wanted system behaviour change.
	20	*
	21	* This feature is intended to overcome above mentioned problems. This feature
	22	* allocates memory for extended data per page in certain place rather than
	23	* the struct page itself. This memory can be accessed by the accessor
	24	* functions provided by this code. During the boot process, it checks whether
	25	* allocation of huge chunk of memory is needed or not. If not, it avoids
	26	* allocating memory at all. With this advantage, we can include this feature
	27	* into the kernel in default and can avoid rebuild and solve related problems.
	28	*
	29	* To help these things to work well, there are two callbacks for clients. One
	30	* is the need callback which is mandatory if user wants to avoid useless
	31	* memory allocation at boot-time. The other is optional, init callback, which
	32	* is used to do proper initialization after memory is allocated.
	33	*
	34	* The need callback is used to decide whether extended memory allocation is
	35	* needed or not. Sometimes users want to deactivate some features in this
	36	* boot and extra memory would be unneccessary. In this case, to avoid
	37	* allocating huge chunk of memory, each clients represent their need of
	38	* extra memory through the need callback. If one of the need callbacks
	39	* returns true, it means that someone needs extra memory so that
	40	* page extension core should allocates memory for page extension. If
	41	* none of need callbacks return true, memory isn't needed at all in this boot
	42	* and page extension core can skip to allocate memory. As result,
	43	* none of memory is wasted.
	44	*
980ac167 JK	45	* When need callback returns true, page_ext checks if there is a request for
	46	* extra memory through size in struct page_ext_operations. If it is non-zero,
	47	* extra space is allocated for each page_ext entry and offset is returned to
	48	* user through offset in struct page_ext_operations.
	49	*
eefa864b JK	50	* The init callback is used to do proper initialization after page extension
	51	* is completely initialized. In sparse memory system, extra memory is
	52	* allocated some time later than memmap is allocated. In other words, lifetime
	53	* of memory for page extension isn't same with memmap for struct page.
	54	* Therefore, clients can't store extra data until page extension is
	55	* initialized, even if pages are allocated and used freely. This could
	56	* cause inadequate state of extra data per page, so, to prevent it, client
	57	* can utilize this callback to initialize the state of it correctly.
	58	*/
	59
	60	static struct page_ext_operations *page_ext_ops[] = {
e30825f1 JK	61	&debug_guardpage_ops,
	62	#ifdef CONFIG_PAGE_POISONING
	63	&page_poisoning_ops,
	64	#endif
48c96a36 JK	65	#ifdef CONFIG_PAGE_OWNER
	66	&page_owner_ops,
	67	#endif
33c3fc71 VD	68	#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
	69	&page_idle_ops,
	70	#endif
eefa864b JK	71	};
	72
	73	static unsigned long total_usage;
980ac167	74	static unsigned long extra_mem;
eefa864b JK	75
	76	static bool __init invoke_need_callbacks(void)
	77	{
	78	int i;
	79	int entries = ARRAY_SIZE(page_ext_ops);
980ac167	80	bool need = false;
eefa864b JK	81
eefa864b JK	82	for (i = 0; i < entries; i++) {
980ac167 JK	83	if (page_ext_ops[i]->need && page_ext_ops[i]->need()) {
	84	page_ext_ops[i]->offset = sizeof(struct page_ext) +
	85	extra_mem;
	86	extra_mem += page_ext_ops[i]->size;
	87	need = true;
	88	}
eefa864b JK	89	}
eefa864b JK	90
980ac167	91	return need;
eefa864b JK	92	}
	93
	94	static void __init invoke_init_callbacks(void)
	95	{
	96	int i;
	97	int entries = ARRAY_SIZE(page_ext_ops);
	98
	99	for (i = 0; i < entries; i++) {
	100	if (page_ext_ops[i]->init)
	101	page_ext_ops[i]->init();
	102	}
	103	}
	104
980ac167 JK	105	static unsigned long get_entry_size(void)
	106	{
	107	return sizeof(struct page_ext) + extra_mem;
	108	}
	109
	110	static inline struct page_ext get_entry(void base, unsigned long index)
	111	{
	112	return base + get_entry_size() * index;
	113	}
	114
eefa864b JK	115	#if !defined(CONFIG_SPARSEMEM)
	116
	117
	118	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	119	{
	120	pgdat->node_page_ext = NULL;
	121	}
	122
	123	struct page_ext lookup_page_ext(struct page page)
	124	{
	125	unsigned long pfn = page_to_pfn(page);
0b06bb3f	126	unsigned long index;
eefa864b JK	127	struct page_ext *base;
	128
	129	base = NODE_DATA(page_to_nid(page))->node_page_ext;
1414c7f4	130	#if defined(CONFIG_DEBUG_VM) \|\| defined(CONFIG_PAGE_POISONING)
eefa864b JK	131	/*
	132	* The sanity checks the page allocator does upon freeing a
	133	* page can reach here before the page_ext arrays are
	134	* allocated when feeding a range of pages to the allocator
	135	* for the first time during bootup or memory hotplug.
1414c7f4 LA	136	*
	137	* This check is also necessary for ensuring page poisoning
	138	* works as expected when enabled
eefa864b JK	139	*/
	140	if (unlikely(!base))
	141	return NULL;
	142	#endif
0b06bb3f	143	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
eefa864b	144	MAX_ORDER_NR_PAGES);
980ac167	145	return get_entry(base, index);
eefa864b JK	146	}
	147
	148	static int __init alloc_node_page_ext(int nid)
	149	{
	150	struct page_ext *base;
	151	unsigned long table_size;
	152	unsigned long nr_pages;
	153
	154	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	155	if (!nr_pages)
	156	return 0;
	157
	158	/*
	159	* Need extra space if node range is not aligned with
	160	* MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
	161	* checks buddy's status, range could be out of exact node range.
	162	*/
	163	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) \|\|
	164	!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
	165	nr_pages += MAX_ORDER_NR_PAGES;
	166
980ac167	167	table_size = get_entry_size() * nr_pages;
eefa864b JK	168
	169	base = memblock_virt_alloc_try_nid_nopanic(
	170	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
	171	BOOTMEM_ALLOC_ACCESSIBLE, nid);
	172	if (!base)
	173	return -ENOMEM;
	174	NODE_DATA(nid)->node_page_ext = base;
	175	total_usage += table_size;
	176	return 0;
	177	}
	178
	179	void __init page_ext_init_flatmem(void)
	180	{
	181
	182	int nid, fail;
	183
	184	if (!invoke_need_callbacks())
	185	return;
	186
	187	for_each_online_node(nid) {
	188	fail = alloc_node_page_ext(nid);
	189	if (fail)
	190	goto fail;
	191	}
	192	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	193	invoke_init_callbacks();
	194	return;
	195
	196	fail:
	197	pr_crit("allocation of page_ext failed.\n");
	198	panic("Out of memory");
	199	}
	200
	201	#else /* CONFIG_FLAT_NODE_MEM_MAP */
	202
	203	struct page_ext lookup_page_ext(struct page page)
	204	{
	205	unsigned long pfn = page_to_pfn(page);
	206	struct mem_section *section = __pfn_to_section(pfn);
1414c7f4	207	#if defined(CONFIG_DEBUG_VM) \|\| defined(CONFIG_PAGE_POISONING)
eefa864b JK	208	/*
	209	* The sanity checks the page allocator does upon freeing a
	210	* page can reach here before the page_ext arrays are
	211	* allocated when feeding a range of pages to the allocator
	212	* for the first time during bootup or memory hotplug.
1414c7f4 LA	213	*
	214	* This check is also necessary for ensuring page poisoning
	215	* works as expected when enabled
eefa864b JK	216	*/
	217	if (!section->page_ext)
	218	return NULL;
	219	#endif
980ac167	220	return get_entry(section->page_ext, pfn);
eefa864b JK	221	}
	222
	223	static void *__meminit alloc_page_ext(size_t size, int nid)
	224	{
	225	gfp_t flags = GFP_KERNEL \| __GFP_ZERO \| __GFP_NOWARN;
	226	void *addr = NULL;
	227
	228	addr = alloc_pages_exact_nid(nid, size, flags);
	229	if (addr) {
	230	kmemleak_alloc(addr, size, 1, flags);
	231	return addr;
	232	}
	233
	234	if (node_state(nid, N_HIGH_MEMORY))
	235	addr = vzalloc_node(size, nid);
	236	else
	237	addr = vzalloc(size);
	238
	239	return addr;
	240	}
	241
	242	static int __meminit init_section_page_ext(unsigned long pfn, int nid)
	243	{
	244	struct mem_section *section;
	245	struct page_ext *base;
	246	unsigned long table_size;
	247
	248	section = __pfn_to_section(pfn);
	249
	250	if (section->page_ext)
	251	return 0;
	252
980ac167	253	table_size = get_entry_size() * PAGES_PER_SECTION;
eefa864b JK	254	base = alloc_page_ext(table_size, nid);
	255
	256	/*
	257	* The value stored in section->page_ext is (base - pfn)
	258	* and it does not point to the memory block allocated above,
	259	* causing kmemleak false positives.
	260	*/
	261	kmemleak_not_leak(base);
	262
	263	if (!base) {
	264	pr_err("page ext allocation failure\n");
	265	return -ENOMEM;
	266	}
	267
	268	/*
	269	* The passed "pfn" may not be aligned to SECTION. For the calculation
	270	* we need to apply a mask.
	271	*/
	272	pfn &= PAGE_SECTION_MASK;
980ac167	273	section->page_ext = (void )base - get_entry_size() pfn;
eefa864b JK	274	total_usage += table_size;
	275	return 0;
	276	}
	277	#ifdef CONFIG_MEMORY_HOTPLUG
	278	static void free_page_ext(void *addr)
	279	{
	280	if (is_vmalloc_addr(addr)) {
	281	vfree(addr);
	282	} else {
	283	struct page *page = virt_to_page(addr);
	284	size_t table_size;
	285
980ac167	286	table_size = get_entry_size() * PAGES_PER_SECTION;
eefa864b JK	287
	288	BUG_ON(PageReserved(page));
	289	free_pages_exact(addr, table_size);
	290	}
	291	}
	292
	293	static void __free_page_ext(unsigned long pfn)
	294	{
	295	struct mem_section *ms;
	296	struct page_ext *base;
	297
	298	ms = __pfn_to_section(pfn);
	299	if (!ms \|\| !ms->page_ext)
	300	return;
980ac167	301	base = get_entry(ms->page_ext, pfn);
eefa864b JK	302	free_page_ext(base);
	303	ms->page_ext = NULL;
	304	}
	305
	306	static int __meminit online_page_ext(unsigned long start_pfn,
	307	unsigned long nr_pages,
	308	int nid)
	309	{
	310	unsigned long start, end, pfn;
	311	int fail = 0;
	312
	313	start = SECTION_ALIGN_DOWN(start_pfn);
	314	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	315
	316	if (nid == -1) {
	317	/*
	318	* In this case, "nid" already exists and contains valid memory.
	319	* "start_pfn" passed to us is a pfn which is an arg for
	320	* online__pages(), and start_pfn should exist.
	321	*/
	322	nid = pfn_to_nid(start_pfn);
	323	VM_BUG_ON(!node_state(nid, N_ONLINE));
	324	}
	325
	326	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
	327	if (!pfn_present(pfn))
	328	continue;
	329	fail = init_section_page_ext(pfn, nid);
	330	}
	331	if (!fail)
	332	return 0;
	333
	334	/* rollback */
	335	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	336	__free_page_ext(pfn);
	337
	338	return -ENOMEM;
	339	}
	340
	341	static int __meminit offline_page_ext(unsigned long start_pfn,
	342	unsigned long nr_pages, int nid)
	343	{
	344	unsigned long start, end, pfn;
	345
	346	start = SECTION_ALIGN_DOWN(start_pfn);
	347	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	348
	349	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	350	__free_page_ext(pfn);
	351	return 0;
	352
	353	}
	354
	355	static int __meminit page_ext_callback(struct notifier_block *self,
	356	unsigned long action, void *arg)
	357	{
	358	struct memory_notify *mn = arg;
	359	int ret = 0;
	360
	361	switch (action) {
	362	case MEM_GOING_ONLINE:
	363	ret = online_page_ext(mn->start_pfn,
	364	mn->nr_pages, mn->status_change_nid);
	365	break;
366	case MEM_OFFLINE:
367	offline_page_ext(mn->start_pfn,
368	mn->nr_pages, mn->status_change_nid);
369	break;
370	case MEM_CANCEL_ONLINE:
371	offline_page_ext(mn->start_pfn,
372	mn->nr_pages, mn->status_change_nid);
373	break;
374	case MEM_GOING_OFFLINE:
375	break;
376	case MEM_ONLINE:
377	case MEM_CANCEL_OFFLINE:
378	break;
379	}
380
381	return notifier_from_errno(ret);
382	}
383
384	#endif
385
386	void __init page_ext_init(void)
387	{
388	unsigned long pfn;
389	int nid;
390
391	if (!invoke_need_callbacks())
392	return;
393
394	for_each_node_state(nid, N_MEMORY) {
395	unsigned long start_pfn, end_pfn;
396
397	start_pfn = node_start_pfn(nid);
398	end_pfn = node_end_pfn(nid);
399	/*
400	* start_pfn and end_pfn may not be aligned to SECTION and the
401	* page->flags of out of node pages are not initialized. So we
402	* scan [start_pfn, the biggest section's pfn < end_pfn) here.
403	*/
404	for (pfn = start_pfn; pfn < end_pfn;
405	pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
406
407	if (!pfn_valid(pfn))
408	continue;
409	/*
410	* Nodes's pfns can be overlapping.
411	* We know some arch can have a nodes layout such as
412	* -------------pfn-------------->
413	* N0 \| N1 \| N2 \| N0 \| N1 \| N2\|....
fe53ca54 YS	414	*
fe53ca54 YS	415	* Take into account DEFERRED_STRUCT_PAGE_INIT.
eefa864b	416	*/
fe53ca54	417	if (early_pfn_to_nid(pfn) != nid)
eefa864b JK	418	continue;
	419	if (init_section_page_ext(pfn, nid))
	420	goto oom;
	421	}
	422	}
	423	hotplug_memory_notifier(page_ext_callback, 0);
	424	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	425	invoke_init_callbacks();
	426	return;
	427
	428	oom:
	429	panic("Out of memory");
	430	}
	431
	432	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	433	{
	434	}
	435
	436	#endif