[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>

/*
 * 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.
 *
 * 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
};

static unsigned long total_usage;

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

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->need && page_ext_ops[i]->need())
			return true;
	}

	return false;
}

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();
	}
}

#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 offset;
	struct page_ext *base;

	base = NODE_DATA(page_to_nid(page))->node_page_ext;
#ifdef CONFIG_DEBUG_VM
	/*
	 * 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.
	 */
	if (unlikely(!base))
		return NULL;
#endif
	offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
					MAX_ORDER_NR_PAGES);
	return base + offset;
}

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