[thirdparty/kernel/stable.git] / mm / page_ext.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memblock.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>
#include <linux/page_table_check.h>
#include <linux/rcupdate.h>
#include <linux/pgalloc_tag.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 unnecessary. 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.
 */

#ifdef CONFIG_SPARSEMEM
#define PAGE_EXT_INVALID       (0x1)
#endif

#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
static bool need_page_idle(void)
{
	return true;
}
static struct page_ext_operations page_idle_ops __initdata = {
	.need = need_page_idle,
	.need_shared_flags = true,
};
#endif

static struct page_ext_operations *page_ext_ops[] __initdata = {
#ifdef CONFIG_PAGE_OWNER
	&page_owner_ops,
#endif
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
	&page_idle_ops,
#endif
#ifdef CONFIG_MEM_ALLOC_PROFILING
	&page_alloc_tagging_ops,
#endif
#ifdef CONFIG_PAGE_TABLE_CHECK
	&page_table_check_ops,
#endif
};

unsigned long page_ext_size;

static unsigned long total_usage;

#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
/*
 * To ensure correct allocation tagging for pages, page_ext should be available
 * before the first page allocation. Otherwise early task stacks will be
 * allocated before page_ext initialization and missing tags will be flagged.
 */
bool early_page_ext __meminitdata = true;
#else
bool early_page_ext __meminitdata;
#endif
static int __init setup_early_page_ext(char *str)
{
	early_page_ext = true;
	return 0;
}
early_param("early_page_ext", setup_early_page_ext);

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()) {
			if (page_ext_ops[i]->need_shared_flags) {
				page_ext_size = sizeof(struct page_ext);
				break;
			}
		}
	}

	for (i = 0; i < entries; i++) {
		if (page_ext_ops[i]->need()) {
			page_ext_ops[i]->offset = page_ext_size;
			page_ext_size += 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 inline struct page_ext *get_entry(void *base, unsigned long index)
{
	return base + page_ext_size * index;
}

#ifndef CONFIG_SPARSEMEM
void __init page_ext_init_flatmem_late(void)
{
	invoke_init_callbacks();
}

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

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

	WARN_ON_ONCE(!rcu_read_lock_held());
	base = NODE_DATA(page_to_nid(page))->node_page_ext;
	/*
	 * 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;
	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 = page_ext_size * nr_pages;

	base = memblock_alloc_try_nid(
			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
			MEMBLOCK_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);
	return;

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

#else /* CONFIG_SPARSEMEM */
static bool page_ext_invalid(struct page_ext *page_ext)
{
	return !page_ext || (((unsigned long)page_ext & PAGE_EXT_INVALID) == PAGE_EXT_INVALID);
}

static struct page_ext *lookup_page_ext(const struct page *page)
{
	unsigned long pfn = page_to_pfn(page);
	struct mem_section *section = __pfn_to_section(pfn);
	struct page_ext *page_ext = READ_ONCE(section->page_ext);

	WARN_ON_ONCE(!rcu_read_lock_held());
	/*
	 * 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 (page_ext_invalid(page_ext))
		return NULL;
	return get_entry(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;
	}

	addr = vzalloc_node(size, nid);

	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 = page_ext_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 - page_ext_size * pfn;
	total_usage += table_size;
	return 0;
}

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 = page_ext_size * PAGES_PER_SECTION;

		BUG_ON(PageReserved(page));
		kmemleak_free(addr);
		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 = READ_ONCE(ms->page_ext);
	/*
	 * page_ext here can be valid while doing the roll back
	 * operation in online_page_ext().
	 */
	if (page_ext_invalid(base))
		base = (void *)base - PAGE_EXT_INVALID;
	WRITE_ONCE(ms->page_ext, NULL);

	base = get_entry(base, pfn);
	free_page_ext(base);
}

static void __invalidate_page_ext(unsigned long pfn)
{
	struct mem_section *ms;
	void *val;

	ms = __pfn_to_section(pfn);
	if (!ms || !ms->page_ext)
		return;
	val = (void *)ms->page_ext + PAGE_EXT_INVALID;
	WRITE_ONCE(ms->page_ext, val);
}

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 == NUMA_NO_NODE) {
		/*
		 * 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_online(nid));
	}

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

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

	return -ENOMEM;
}

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

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

	/*
	 * Freeing of page_ext is done in 3 steps to avoid
	 * use-after-free of it:
	 * 1) Traverse all the sections and mark their page_ext
	 *    as invalid.
	 * 2) Wait for all the existing users of page_ext who
	 *    started before invalidation to finish.
	 * 3) Free the page_ext.
	 */
	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
		__invalidate_page_ext(pfn);

	synchronize_rcu();

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

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);
		break;
	case MEM_CANCEL_ONLINE:
		offline_page_ext(mn->start_pfn,
				mn->nr_pages);
		break;
	case MEM_GOING_OFFLINE:
		break;
	case MEM_ONLINE:
	case MEM_CANCEL_OFFLINE:
		break;
	}

	return notifier_from_errno(ret);
}

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;
			cond_resched();
		}
	}
	hotplug_memory_notifier(page_ext_callback, DEFAULT_CALLBACK_PRI);
	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

/**
 * page_ext_get() - Get the extended information for a page.
 * @page: The page we're interested in.
 *
 * Ensures that the page_ext will remain valid until page_ext_put()
 * is called.
 *
 * Return: NULL if no page_ext exists for this page.
 * Context: Any context.  Caller may not sleep until they have called
 * page_ext_put().
 */
struct page_ext *page_ext_get(const struct page *page)
{
	struct page_ext *page_ext;

	rcu_read_lock();
	page_ext = lookup_page_ext(page);
	if (!page_ext) {
		rcu_read_unlock();
		return NULL;
	}

	return page_ext;
}

/**
 * page_ext_put() - Working with page extended information is done.
 * @page_ext: Page extended information received from page_ext_get().
 *
 * The page extended information of the page may not be valid after this
 * function is called.
 *
 * Return: None.
 * Context: Any context with corresponding page_ext_get() is called.
 */
void page_ext_put(struct page_ext *page_ext)
{
	if (unlikely(!page_ext))
		return;

	rcu_read_unlock();
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
eefa864b JK	2	#include <linux/mm.h>
eefa864b JK	3	#include <linux/mmzone.h>
57c8a661	4	#include <linux/memblock.h>
eefa864b JK	5	#include <linux/page_ext.h>
	6	#include <linux/memory.h>
	7	#include <linux/vmalloc.h>
	8	#include <linux/kmemleak.h>
48c96a36	9	#include <linux/page_owner.h>
33c3fc71	10	#include <linux/page_idle.h>
df4e817b	11	#include <linux/page_table_check.h>
b1d5488a	12	#include <linux/rcupdate.h>
dcfe378c	13	#include <linux/pgalloc_tag.h>
eefa864b JK	14
	15	/*
	16	* struct page extension
	17	*
	18	* This is the feature to manage memory for extended data per page.
	19	*
	20	* Until now, we must modify struct page itself to store extra data per page.
	21	* This requires rebuilding the kernel and it is really time consuming process.
	22	* And, sometimes, rebuild is impossible due to third party module dependency.
	23	* At last, enlarging struct page could cause un-wanted system behaviour change.
	24	*
	25	* This feature is intended to overcome above mentioned problems. This feature
	26	* allocates memory for extended data per page in certain place rather than
	27	* the struct page itself. This memory can be accessed by the accessor
	28	* functions provided by this code. During the boot process, it checks whether
	29	* allocation of huge chunk of memory is needed or not. If not, it avoids
	30	* allocating memory at all. With this advantage, we can include this feature
	31	* into the kernel in default and can avoid rebuild and solve related problems.
	32	*
	33	* To help these things to work well, there are two callbacks for clients. One
	34	* is the need callback which is mandatory if user wants to avoid useless
	35	* memory allocation at boot-time. The other is optional, init callback, which
	36	* is used to do proper initialization after memory is allocated.
	37	*
	38	* The need callback is used to decide whether extended memory allocation is
	39	* needed or not. Sometimes users want to deactivate some features in this
8958b249	40	* boot and extra memory would be unnecessary. In this case, to avoid
eefa864b JK	41	* allocating huge chunk of memory, each clients represent their need of
	42	* extra memory through the need callback. If one of the need callbacks
	43	* returns true, it means that someone needs extra memory so that
	44	* page extension core should allocates memory for page extension. If
	45	* none of need callbacks return true, memory isn't needed at all in this boot
	46	* and page extension core can skip to allocate memory. As result,
	47	* none of memory is wasted.
	48	*
980ac167 JK	49	* When need callback returns true, page_ext checks if there is a request for
	50	* extra memory through size in struct page_ext_operations. If it is non-zero,
	51	* extra space is allocated for each page_ext entry and offset is returned to
	52	* user through offset in struct page_ext_operations.
	53	*
eefa864b JK	54	* The init callback is used to do proper initialization after page extension
	55	* is completely initialized. In sparse memory system, extra memory is
	56	* allocated some time later than memmap is allocated. In other words, lifetime
	57	* of memory for page extension isn't same with memmap for struct page.
	58	* Therefore, clients can't store extra data until page extension is
	59	* initialized, even if pages are allocated and used freely. This could
	60	* cause inadequate state of extra data per page, so, to prevent it, client
	61	* can utilize this callback to initialize the state of it correctly.
	62	*/
	63
b1d5488a CTK	64	#ifdef CONFIG_SPARSEMEM
	65	#define PAGE_EXT_INVALID (0x1)
	66	#endif
	67
1c676e0d SP	68	#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
	69	static bool need_page_idle(void)
	70	{
	71	return true;
	72	}
cab0a7c1	73	static struct page_ext_operations page_idle_ops __initdata = {
1c676e0d	74	.need = need_page_idle,
6189eb82	75	.need_shared_flags = true,
1c676e0d SP	76	};
	77	#endif
	78
cab0a7c1	79	static struct page_ext_operations *page_ext_ops[] __initdata = {
48c96a36 JK	80	#ifdef CONFIG_PAGE_OWNER
	81	&page_owner_ops,
	82	#endif
1c676e0d	83	#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
33c3fc71 VD	84	&page_idle_ops,
33c3fc71 VD	85	#endif
dcfe378c SB	86	#ifdef CONFIG_MEM_ALLOC_PROFILING
	87	&page_alloc_tagging_ops,
	88	#endif
df4e817b PT	89	#ifdef CONFIG_PAGE_TABLE_CHECK
	90	&page_table_check_ops,
	91	#endif
eefa864b JK	92	};
eefa864b JK	93
6189eb82	94	unsigned long page_ext_size;
5556cfe8	95
eefa864b JK	96	static unsigned long total_usage;
eefa864b JK	97
26865a1b SB	98	#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
	99	/*
	100	* To ensure correct allocation tagging for pages, page_ext should be available
	101	* before the first page allocation. Otherwise early task stacks will be
	102	* allocated before page_ext initialization and missing tags will be flagged.
	103	*/
	104	bool early_page_ext __meminitdata = true;
	105	#else
7ec7096b	106	bool early_page_ext __meminitdata;
26865a1b	107	#endif
c4f20f14 LZ	108	static int __init setup_early_page_ext(char *str)
	109	{
	110	early_page_ext = true;
	111	return 0;
	112	}
	113	early_param("early_page_ext", setup_early_page_ext);
	114
eefa864b JK	115	static bool __init invoke_need_callbacks(void)
	116	{
	117	int i;
	118	int entries = ARRAY_SIZE(page_ext_ops);
980ac167	119	bool need = false;
eefa864b JK	120
eefa864b JK	121	for (i = 0; i < entries; i++) {
6189eb82 PT	122	if (page_ext_ops[i]->need()) {
	123	if (page_ext_ops[i]->need_shared_flags) {
	124	page_ext_size = sizeof(struct page_ext);
	125	break;
	126	}
	127	}
	128	}
	129
	130	for (i = 0; i < entries; i++) {
	131	if (page_ext_ops[i]->need()) {
5556cfe8 VB	132	page_ext_ops[i]->offset = page_ext_size;
5556cfe8 VB	133	page_ext_size += page_ext_ops[i]->size;
980ac167 JK	134	need = true;
980ac167 JK	135	}
eefa864b JK	136	}
eefa864b JK	137
980ac167	138	return need;
eefa864b JK	139	}
	140
	141	static void __init invoke_init_callbacks(void)
	142	{
	143	int i;
	144	int entries = ARRAY_SIZE(page_ext_ops);
	145
	146	for (i = 0; i < entries; i++) {
	147	if (page_ext_ops[i]->init)
	148	page_ext_ops[i]->init();
	149	}
	150	}
	151
980ac167 JK	152	static inline struct page_ext get_entry(void base, unsigned long index)
980ac167 JK	153	{
5556cfe8	154	return base + page_ext_size * index;
980ac167 JK	155	}
980ac167 JK	156
eb0da7f6 KS	157	#ifndef CONFIG_SPARSEMEM
eb0da7f6 KS	158	void __init page_ext_init_flatmem_late(void)
b1d5488a	159	{
eb0da7f6	160	invoke_init_callbacks();
b1d5488a	161	}
eefa864b JK	162
	163	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	164	{
	165	pgdat->node_page_ext = NULL;
	166	}
	167
b1d5488a	168	static struct page_ext lookup_page_ext(const struct page page)
eefa864b JK	169	{
eefa864b JK	170	unsigned long pfn = page_to_pfn(page);
0b06bb3f	171	unsigned long index;
eefa864b JK	172	struct page_ext *base;
eefa864b JK	173
b1d5488a	174	WARN_ON_ONCE(!rcu_read_lock_held());
eefa864b	175	base = NODE_DATA(page_to_nid(page))->node_page_ext;
eefa864b JK	176	/*
	177	* The sanity checks the page allocator does upon freeing a
	178	* page can reach here before the page_ext arrays are
	179	* allocated when feeding a range of pages to the allocator
	180	* for the first time during bootup or memory hotplug.
	181	*/
	182	if (unlikely(!base))
	183	return NULL;
0b06bb3f	184	index = pfn - round_down(node_start_pfn(page_to_nid(page)),
eefa864b	185	MAX_ORDER_NR_PAGES);
980ac167	186	return get_entry(base, index);
eefa864b JK	187	}
	188
	189	static int __init alloc_node_page_ext(int nid)
	190	{
	191	struct page_ext *base;
	192	unsigned long table_size;
	193	unsigned long nr_pages;
	194
	195	nr_pages = NODE_DATA(nid)->node_spanned_pages;
	196	if (!nr_pages)
	197	return 0;
	198
	199	/*
	200	* Need extra space if node range is not aligned with
	201	* MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
	202	* checks buddy's status, range could be out of exact node range.
	203	*/
	204	if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) \|\|
	205	!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
	206	nr_pages += MAX_ORDER_NR_PAGES;
	207
5556cfe8	208	table_size = page_ext_size * nr_pages;
eefa864b	209
26fb3dae	210	base = memblock_alloc_try_nid(
eefa864b	211	table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
97ad1087	212	MEMBLOCK_ALLOC_ACCESSIBLE, nid);
eefa864b JK	213	if (!base)
	214	return -ENOMEM;
	215	NODE_DATA(nid)->node_page_ext = base;
	216	total_usage += table_size;
	217	return 0;
	218	}
	219
	220	void __init page_ext_init_flatmem(void)
	221	{
	222
	223	int nid, fail;
	224
	225	if (!invoke_need_callbacks())
	226	return;
	227
	228	for_each_online_node(nid) {
	229	fail = alloc_node_page_ext(nid);
	230	if (fail)
	231	goto fail;
	232	}
	233	pr_info("allocated %ld bytes of page_ext\n", total_usage);
eefa864b JK	234	return;
	235
	236	fail:
	237	pr_crit("allocation of page_ext failed.\n");
	238	panic("Out of memory");
	239	}
	240
d1fea155	241	#else /* CONFIG_SPARSEMEM */
b1d5488a CTK	242	static bool page_ext_invalid(struct page_ext *page_ext)
	243	{
	244	return !page_ext \|\| (((unsigned long)page_ext & PAGE_EXT_INVALID) == PAGE_EXT_INVALID);
	245	}
eefa864b	246
b1d5488a	247	static struct page_ext lookup_page_ext(const struct page page)
eefa864b JK	248	{
	249	unsigned long pfn = page_to_pfn(page);
	250	struct mem_section *section = __pfn_to_section(pfn);
b1d5488a CTK	251	struct page_ext *page_ext = READ_ONCE(section->page_ext);
	252
	253	WARN_ON_ONCE(!rcu_read_lock_held());
eefa864b JK	254	/*
	255	* The sanity checks the page allocator does upon freeing a
	256	* page can reach here before the page_ext arrays are
	257	* allocated when feeding a range of pages to the allocator
	258	* for the first time during bootup or memory hotplug.
	259	*/
b1d5488a	260	if (page_ext_invalid(page_ext))
eefa864b	261	return NULL;
b1d5488a	262	return get_entry(page_ext, pfn);
eefa864b JK	263	}
	264
	265	static void *__meminit alloc_page_ext(size_t size, int nid)
	266	{
	267	gfp_t flags = GFP_KERNEL \| __GFP_ZERO \| __GFP_NOWARN;
	268	void *addr = NULL;
	269
	270	addr = alloc_pages_exact_nid(nid, size, flags);
	271	if (addr) {
	272	kmemleak_alloc(addr, size, 1, flags);
	273	return addr;
	274	}
	275
b95046b0	276	addr = vzalloc_node(size, nid);
eefa864b JK	277
	278	return addr;
	279	}
	280
	281	static int __meminit init_section_page_ext(unsigned long pfn, int nid)
	282	{
	283	struct mem_section *section;
	284	struct page_ext *base;
	285	unsigned long table_size;
	286
	287	section = __pfn_to_section(pfn);
	288
	289	if (section->page_ext)
	290	return 0;
	291
5556cfe8	292	table_size = page_ext_size * PAGES_PER_SECTION;
eefa864b JK	293	base = alloc_page_ext(table_size, nid);
	294
	295	/*
	296	* The value stored in section->page_ext is (base - pfn)
	297	* and it does not point to the memory block allocated above,
	298	* causing kmemleak false positives.
	299	*/
	300	kmemleak_not_leak(base);
	301
	302	if (!base) {
	303	pr_err("page ext allocation failure\n");
	304	return -ENOMEM;
	305	}
	306
	307	/*
	308	* The passed "pfn" may not be aligned to SECTION. For the calculation
	309	* we need to apply a mask.
	310	*/
	311	pfn &= PAGE_SECTION_MASK;
5556cfe8	312	section->page_ext = (void )base - page_ext_size pfn;
eefa864b JK	313	total_usage += table_size;
	314	return 0;
	315	}
76af6a05	316
eefa864b JK	317	static void free_page_ext(void *addr)
	318	{
	319	if (is_vmalloc_addr(addr)) {
	320	vfree(addr);
	321	} else {
	322	struct page *page = virt_to_page(addr);
	323	size_t table_size;
	324
5556cfe8	325	table_size = page_ext_size * PAGES_PER_SECTION;
eefa864b JK	326
eefa864b JK	327	BUG_ON(PageReserved(page));
0c815854	328	kmemleak_free(addr);
eefa864b JK	329	free_pages_exact(addr, table_size);
	330	}
	331	}
	332
	333	static void __free_page_ext(unsigned long pfn)
	334	{
	335	struct mem_section *ms;
	336	struct page_ext *base;
	337
	338	ms = __pfn_to_section(pfn);
	339	if (!ms \|\| !ms->page_ext)
	340	return;
b1d5488a CTK	341
	342	base = READ_ONCE(ms->page_ext);
	343	/*
	344	* page_ext here can be valid while doing the roll back
	345	* operation in online_page_ext().
	346	*/
	347	if (page_ext_invalid(base))
	348	base = (void *)base - PAGE_EXT_INVALID;
	349	WRITE_ONCE(ms->page_ext, NULL);
	350
	351	base = get_entry(base, pfn);
eefa864b	352	free_page_ext(base);
b1d5488a CTK	353	}
	354
	355	static void __invalidate_page_ext(unsigned long pfn)
	356	{
	357	struct mem_section *ms;
	358	void *val;
	359
	360	ms = __pfn_to_section(pfn);
	361	if (!ms \|\| !ms->page_ext)
	362	return;
	363	val = (void *)ms->page_ext + PAGE_EXT_INVALID;
	364	WRITE_ONCE(ms->page_ext, val);
eefa864b JK	365	}
	366
	367	static int __meminit online_page_ext(unsigned long start_pfn,
	368	unsigned long nr_pages,
	369	int nid)
	370	{
	371	unsigned long start, end, pfn;
	372	int fail = 0;
	373
	374	start = SECTION_ALIGN_DOWN(start_pfn);
	375	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	376
98fa15f3	377	if (nid == NUMA_NO_NODE) {
eefa864b JK	378	/*
	379	* In this case, "nid" already exists and contains valid memory.
	380	* "start_pfn" passed to us is a pfn which is an arg for
	381	* online__pages(), and start_pfn should exist.
	382	*/
	383	nid = pfn_to_nid(start_pfn);
30a51400	384	VM_BUG_ON(!node_online(nid));
eefa864b JK	385	}
eefa864b JK	386
dccacf8d	387	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION)
eefa864b	388	fail = init_section_page_ext(pfn, nid);
eefa864b JK	389	if (!fail)
	390	return 0;
	391
	392	/* rollback */
3c09be5a	393	end = pfn - PAGES_PER_SECTION;
eefa864b JK	394	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	395	__free_page_ext(pfn);
	396
	397	return -ENOMEM;
	398	}
	399
063ff7cd	400	static void __meminit offline_page_ext(unsigned long start_pfn,
7b5a0b66	401	unsigned long nr_pages)
eefa864b JK	402	{
	403	unsigned long start, end, pfn;
	404
	405	start = SECTION_ALIGN_DOWN(start_pfn);
	406	end = SECTION_ALIGN_UP(start_pfn + nr_pages);
	407
b1d5488a CTK	408	/*
	409	* Freeing of page_ext is done in 3 steps to avoid
	410	* use-after-free of it:
	411	* 1) Traverse all the sections and mark their page_ext
	412	* as invalid.
	413	* 2) Wait for all the existing users of page_ext who
	414	* started before invalidation to finish.
	415	* 3) Free the page_ext.
	416	*/
	417	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
	418	__invalidate_page_ext(pfn);
	419
	420	synchronize_rcu();
	421
eefa864b JK	422	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
eefa864b JK	423	__free_page_ext(pfn);
eefa864b JK	424	}
	425
	426	static int __meminit page_ext_callback(struct notifier_block *self,
	427	unsigned long action, void *arg)
	428	{
	429	struct memory_notify *mn = arg;
	430	int ret = 0;
	431
	432	switch (action) {
	433	case MEM_GOING_ONLINE:
	434	ret = online_page_ext(mn->start_pfn,
	435	mn->nr_pages, mn->status_change_nid);
	436	break;
	437	case MEM_OFFLINE:
	438	offline_page_ext(mn->start_pfn,
7b5a0b66	439	mn->nr_pages);
eefa864b JK	440	break;
	441	case MEM_CANCEL_ONLINE:
	442	offline_page_ext(mn->start_pfn,
7b5a0b66	443	mn->nr_pages);
eefa864b JK	444	break;
	445	case MEM_GOING_OFFLINE:
	446	break;
	447	case MEM_ONLINE:
	448	case MEM_CANCEL_OFFLINE:
	449	break;
	450	}
	451
	452	return notifier_from_errno(ret);
	453	}
	454
eefa864b JK	455	void __init page_ext_init(void)
	456	{
	457	unsigned long pfn;
	458	int nid;
	459
	460	if (!invoke_need_callbacks())
	461	return;
	462
	463	for_each_node_state(nid, N_MEMORY) {
	464	unsigned long start_pfn, end_pfn;
	465
	466	start_pfn = node_start_pfn(nid);
	467	end_pfn = node_end_pfn(nid);
	468	/*
	469	* start_pfn and end_pfn may not be aligned to SECTION and the
	470	* page->flags of out of node pages are not initialized. So we
	471	* scan [start_pfn, the biggest section's pfn < end_pfn) here.
	472	*/
	473	for (pfn = start_pfn; pfn < end_pfn;
	474	pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
	475
	476	if (!pfn_valid(pfn))
	477	continue;
	478	/*
	479	* Nodes's pfns can be overlapping.
	480	* We know some arch can have a nodes layout such as
	481	* -------------pfn-------------->
	482	* N0 \| N1 \| N2 \| N0 \| N1 \| N2\|....
	483	*/
2f1ee091	484	if (pfn_to_nid(pfn) != nid)
eefa864b JK	485	continue;
	486	if (init_section_page_ext(pfn, nid))
	487	goto oom;
0fc542b7	488	cond_resched();
eefa864b JK	489	}
eefa864b JK	490	}
1eeaa4fd	491	hotplug_memory_notifier(page_ext_callback, DEFAULT_CALLBACK_PRI);
eefa864b JK	492	pr_info("allocated %ld bytes of page_ext\n", total_usage);
	493	invoke_init_callbacks();
	494	return;
	495
	496	oom:
	497	panic("Out of memory");
	498	}
	499
	500	void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
	501	{
	502	}
	503
	504	#endif
eb0da7f6 KS	505
	506	/**
	507	* page_ext_get() - Get the extended information for a page.
	508	* @page: The page we're interested in.
	509	*
	510	* Ensures that the page_ext will remain valid until page_ext_put()
	511	* is called.
	512	*
	513	* Return: NULL if no page_ext exists for this page.
	514	* Context: Any context. Caller may not sleep until they have called
	515	* page_ext_put().
	516	*/
6e65aa55	517	struct page_ext page_ext_get(const struct page page)
eb0da7f6 KS	518	{
	519	struct page_ext *page_ext;
	520
	521	rcu_read_lock();
	522	page_ext = lookup_page_ext(page);
	523	if (!page_ext) {
	524	rcu_read_unlock();
	525	return NULL;
	526	}
	527
	528	return page_ext;
	529	}
	530
	531	/**
	532	* page_ext_put() - Working with page extended information is done.
	533	* @page_ext: Page extended information received from page_ext_get().
	534	*
	535	* The page extended information of the page may not be valid after this
	536	* function is called.
	537	*
	538	* Return: None.
	539	* Context: Any context with corresponding page_ext_get() is called.
	540	*/
	541	void page_ext_put(struct page_ext *page_ext)
	542	{
	543	if (unlikely(!page_ext))
	544	return;
	545
	546	rcu_read_unlock();
	547	}