[mirror_ubuntu-jammy-kernel.git] / mm / page_vma_mapped.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/mm.h>
#include <linux/rmap.h>
#include <linux/hugetlb.h>
#include <linux/swap.h>
#include <linux/swapops.h>

#include "internal.h"

static inline bool not_found(struct page_vma_mapped_walk *pvmw)
{
	page_vma_mapped_walk_done(pvmw);
	return false;
}

static bool map_pte(struct page_vma_mapped_walk *pvmw)
{
	pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
	if (!(pvmw->flags & PVMW_SYNC)) {
		if (pvmw->flags & PVMW_MIGRATION) {
			if (!is_swap_pte(*pvmw->pte))
				return false;
		} else {
			/*
			 * We get here when we are trying to unmap a private
			 * device page from the process address space. Such
			 * page is not CPU accessible and thus is mapped as
			 * a special swap entry, nonetheless it still does
			 * count as a valid regular mapping for the page (and
			 * is accounted as such in page maps count).
			 *
			 * So handle this special case as if it was a normal
			 * page mapping ie lock CPU page table and returns
			 * true.
			 *
			 * For more details on device private memory see HMM
			 * (include/linux/hmm.h or mm/hmm.c).
			 */
			if (is_swap_pte(*pvmw->pte)) {
				swp_entry_t entry;

				/* Handle un-addressable ZONE_DEVICE memory */
				entry = pte_to_swp_entry(*pvmw->pte);
				if (!is_device_private_entry(entry) &&
				    !is_device_exclusive_entry(entry))
					return false;
			} else if (!pte_present(*pvmw->pte))
				return false;
		}
	}
	pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
	spin_lock(pvmw->ptl);
	return true;
}

static inline bool pfn_is_match(struct page *page, unsigned long pfn)
{
	unsigned long page_pfn = page_to_pfn(page);

	/* normal page and hugetlbfs page */
	if (!PageTransCompound(page) || PageHuge(page))
		return page_pfn == pfn;

	/* THP can be referenced by any subpage */
	return pfn >= page_pfn && pfn - page_pfn < thp_nr_pages(page);
}

/**
 * check_pte - check if @pvmw->page is mapped at the @pvmw->pte
 * @pvmw: page_vma_mapped_walk struct, includes a pair pte and page for checking
 *
 * page_vma_mapped_walk() found a place where @pvmw->page is *potentially*
 * mapped. check_pte() has to validate this.
 *
 * pvmw->pte may point to empty PTE, swap PTE or PTE pointing to
 * arbitrary page.
 *
 * If PVMW_MIGRATION flag is set, returns true if @pvmw->pte contains migration
 * entry that points to @pvmw->page or any subpage in case of THP.
 *
 * If PVMW_MIGRATION flag is not set, returns true if pvmw->pte points to
 * pvmw->page or any subpage in case of THP.
 *
 * Otherwise, return false.
 *
 */
static bool check_pte(struct page_vma_mapped_walk *pvmw)
{
	unsigned long pfn;

	if (pvmw->flags & PVMW_MIGRATION) {
		swp_entry_t entry;
		if (!is_swap_pte(*pvmw->pte))
			return false;
		entry = pte_to_swp_entry(*pvmw->pte);

		if (!is_migration_entry(entry) &&
		    !is_device_exclusive_entry(entry))
			return false;

		pfn = swp_offset(entry);
	} else if (is_swap_pte(*pvmw->pte)) {
		swp_entry_t entry;

		/* Handle un-addressable ZONE_DEVICE memory */
		entry = pte_to_swp_entry(*pvmw->pte);
		if (!is_device_private_entry(entry) &&
		    !is_device_exclusive_entry(entry))
			return false;

		pfn = swp_offset(entry);
	} else {
		if (!pte_present(*pvmw->pte))
			return false;

		pfn = pte_pfn(*pvmw->pte);
	}

	return pfn_is_match(pvmw->page, pfn);
}

static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size)
{
	pvmw->address = (pvmw->address + size) & ~(size - 1);
	if (!pvmw->address)
		pvmw->address = ULONG_MAX;
}

/**
 * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at
 * @pvmw->address
 * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags
 * must be set. pmd, pte and ptl must be NULL.
 *
 * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point
 * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is
 * adjusted if needed (for PTE-mapped THPs).
 *
 * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page
 * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in
 * a loop to find all PTEs that map the THP.
 *
 * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry
 * regardless of which page table level the page is mapped at. @pvmw->pmd is
 * NULL.
 *
 * Returns false if there are no more page table entries for the page in
 * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped.
 *
 * If you need to stop the walk before page_vma_mapped_walk() returned false,
 * use page_vma_mapped_walk_done(). It will do the housekeeping.
 */
bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
{
	struct mm_struct *mm = pvmw->vma->vm_mm;
	struct page *page = pvmw->page;
	unsigned long end;
	pgd_t *pgd;
	p4d_t *p4d;
	pud_t *pud;
	pmd_t pmde;

	/* The only possible pmd mapping has been handled on last iteration */
	if (pvmw->pmd && !pvmw->pte)
		return not_found(pvmw);

	if (unlikely(PageHuge(page))) {
		/* The only possible mapping was handled on last iteration */
		if (pvmw->pte)
			return not_found(pvmw);

		/* when pud is not present, pte will be NULL */
		pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
		if (!pvmw->pte)
			return false;

		pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte);
		spin_lock(pvmw->ptl);
		if (!check_pte(pvmw))
			return not_found(pvmw);
		return true;
	}

	/*
	 * Seek to next pte only makes sense for THP.
	 * But more important than that optimization, is to filter out
	 * any PageKsm page: whose page->index misleads vma_address()
	 * and vma_address_end() to disaster.
	 */
	end = PageTransCompound(page) ?
		vma_address_end(page, pvmw->vma) :
		pvmw->address + PAGE_SIZE;
	if (pvmw->pte)
		goto next_pte;
restart:
	do {
		pgd = pgd_offset(mm, pvmw->address);
		if (!pgd_present(*pgd)) {
			step_forward(pvmw, PGDIR_SIZE);
			continue;
		}
		p4d = p4d_offset(pgd, pvmw->address);
		if (!p4d_present(*p4d)) {
			step_forward(pvmw, P4D_SIZE);
			continue;
		}
		pud = pud_offset(p4d, pvmw->address);
		if (!pud_present(*pud)) {
			step_forward(pvmw, PUD_SIZE);
			continue;
		}

		pvmw->pmd = pmd_offset(pud, pvmw->address);
		/*
		 * Make sure the pmd value isn't cached in a register by the
		 * compiler and used as a stale value after we've observed a
		 * subsequent update.
		 */
		pmde = READ_ONCE(*pvmw->pmd);

		if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
			pvmw->ptl = pmd_lock(mm, pvmw->pmd);
			pmde = *pvmw->pmd;
			if (likely(pmd_trans_huge(pmde))) {
				if (pvmw->flags & PVMW_MIGRATION)
					return not_found(pvmw);
				if (pmd_page(pmde) != page)
					return not_found(pvmw);
				return true;
			}
			if (!pmd_present(pmde)) {
				swp_entry_t entry;

				if (!thp_migration_supported() ||
				    !(pvmw->flags & PVMW_MIGRATION))
					return not_found(pvmw);
				entry = pmd_to_swp_entry(pmde);
				if (!is_migration_entry(entry) ||
				    pfn_swap_entry_to_page(entry) != page)
					return not_found(pvmw);
				return true;
			}
			/* THP pmd was split under us: handle on pte level */
			spin_unlock(pvmw->ptl);
			pvmw->ptl = NULL;
		} else if (!pmd_present(pmde)) {
			/*
			 * If PVMW_SYNC, take and drop THP pmd lock so that we
			 * cannot return prematurely, while zap_huge_pmd() has
			 * cleared *pmd but not decremented compound_mapcount().
			 */
			if ((pvmw->flags & PVMW_SYNC) &&
			    PageTransCompound(page)) {
				spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);

				spin_unlock(ptl);
			}
			step_forward(pvmw, PMD_SIZE);
			continue;
		}
		if (!map_pte(pvmw))
			goto next_pte;
this_pte:
		if (check_pte(pvmw))
			return true;
next_pte:
		do {
			pvmw->address += PAGE_SIZE;
			if (pvmw->address >= end)
				return not_found(pvmw);
			/* Did we cross page table boundary? */
			if ((pvmw->address & (PMD_SIZE - PAGE_SIZE)) == 0) {
				if (pvmw->ptl) {
					spin_unlock(pvmw->ptl);
					pvmw->ptl = NULL;
				}
				pte_unmap(pvmw->pte);
				pvmw->pte = NULL;
				goto restart;
			}
			pvmw->pte++;
			if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) {
				pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
				spin_lock(pvmw->ptl);
			}
		} while (pte_none(*pvmw->pte));

		if (!pvmw->ptl) {
			pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
			spin_lock(pvmw->ptl);
		}
		goto this_pte;
	} while (pvmw->address < end);

	return false;
}

/**
 * page_mapped_in_vma - check whether a page is really mapped in a VMA
 * @page: the page to test
 * @vma: the VMA to test
 *
 * Returns 1 if the page is mapped into the page tables of the VMA, 0
 * if the page is not mapped into the page tables of this VMA.  Only
 * valid for normal file or anonymous VMAs.
 */
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
{
	struct page_vma_mapped_walk pvmw = {
		.page = page,
		.vma = vma,
		.flags = PVMW_SYNC,
	};

	pvmw.address = vma_address(page, vma);
	if (pvmw.address == -EFAULT)
		return 0;
	if (!page_vma_mapped_walk(&pvmw))
		return 0;
	page_vma_mapped_walk_done(&pvmw);
	return 1;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
ace71a19 KS	2	#include <linux/mm.h>
	3	#include <linux/rmap.h>
	4	#include <linux/hugetlb.h>
	5	#include <linux/swap.h>
	6	#include <linux/swapops.h>
	7
	8	#include "internal.h"
	9
ace71a19 KS	10	static inline bool not_found(struct page_vma_mapped_walk *pvmw)
	11	{
	12	page_vma_mapped_walk_done(pvmw);
	13	return false;
	14	}
	15
	16	static bool map_pte(struct page_vma_mapped_walk *pvmw)
	17	{
	18	pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
	19	if (!(pvmw->flags & PVMW_SYNC)) {
	20	if (pvmw->flags & PVMW_MIGRATION) {
	21	if (!is_swap_pte(*pvmw->pte))
	22	return false;
	23	} else {
aab8d052 RC	24	/*
	25	* We get here when we are trying to unmap a private
	26	* device page from the process address space. Such
	27	* page is not CPU accessible and thus is mapped as
	28	* a special swap entry, nonetheless it still does
	29	* count as a valid regular mapping for the page (and
	30	* is accounted as such in page maps count).
	31	*
	32	* So handle this special case as if it was a normal
	33	* page mapping ie lock CPU page table and returns
	34	* true.
	35	*
	36	* For more details on device private memory see HMM
	37	* (include/linux/hmm.h or mm/hmm.c).
	38	*/
	39	if (is_swap_pte(*pvmw->pte)) {
	40	swp_entry_t entry;
	41
	42	/* Handle un-addressable ZONE_DEVICE memory */
	43	entry = pte_to_swp_entry(*pvmw->pte);
b756a3b5 AP	44	if (!is_device_private_entry(entry) &&
b756a3b5 AP	45	!is_device_exclusive_entry(entry))
aab8d052 RC	46	return false;
aab8d052 RC	47	} else if (!pte_present(*pvmw->pte))
ace71a19 KS	48	return false;
	49	}
	50	}
	51	pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
	52	spin_lock(pvmw->ptl);
	53	return true;
	54	}
	55
5b8d6e37	56	static inline bool pfn_is_match(struct page *page, unsigned long pfn)
7222708e	57	{
5b8d6e37 LX	58	unsigned long page_pfn = page_to_pfn(page);
	59
	60	/* normal page and hugetlbfs page */
	61	if (!PageTransCompound(page) \|\| PageHuge(page))
	62	return page_pfn == pfn;
7222708e KS	63
7222708e KS	64	/* THP can be referenced by any subpage */
6c357848	65	return pfn >= page_pfn && pfn - page_pfn < thp_nr_pages(page);
7222708e KS	66	}
7222708e KS	67
0d665e7b KS	68	/**
0d665e7b KS	69	* check_pte - check if @pvmw->page is mapped at the @pvmw->pte
777f303c	70	* @pvmw: page_vma_mapped_walk struct, includes a pair pte and page for checking
0d665e7b KS	71	*
	72	* page_vma_mapped_walk() found a place where @pvmw->page is potentially
	73	* mapped. check_pte() has to validate this.
	74	*
777f303c AS	75	* pvmw->pte may point to empty PTE, swap PTE or PTE pointing to
777f303c AS	76	* arbitrary page.
0d665e7b KS	77	*
	78	* If PVMW_MIGRATION flag is set, returns true if @pvmw->pte contains migration
	79	* entry that points to @pvmw->page or any subpage in case of THP.
	80	*
777f303c AS	81	* If PVMW_MIGRATION flag is not set, returns true if pvmw->pte points to
777f303c AS	82	* pvmw->page or any subpage in case of THP.
0d665e7b KS	83	*
	84	* Otherwise, return false.
	85	*
	86	*/
ace71a19 KS	87	static bool check_pte(struct page_vma_mapped_walk *pvmw)
ace71a19 KS	88	{
0d665e7b KS	89	unsigned long pfn;
0d665e7b KS	90
ace71a19	91	if (pvmw->flags & PVMW_MIGRATION) {
ace71a19 KS	92	swp_entry_t entry;
	93	if (!is_swap_pte(*pvmw->pte))
	94	return false;
	95	entry = pte_to_swp_entry(*pvmw->pte);
a5430dda	96
b756a3b5 AP	97	if (!is_migration_entry(entry) &&
b756a3b5 AP	98	!is_device_exclusive_entry(entry))
ace71a19	99	return false;
a5430dda	100
af5cdaf8	101	pfn = swp_offset(entry);
0d665e7b KS	102	} else if (is_swap_pte(*pvmw->pte)) {
0d665e7b KS	103	swp_entry_t entry;
a5430dda	104
0d665e7b KS	105	/* Handle un-addressable ZONE_DEVICE memory */
0d665e7b KS	106	entry = pte_to_swp_entry(*pvmw->pte);
b756a3b5 AP	107	if (!is_device_private_entry(entry) &&
b756a3b5 AP	108	!is_device_exclusive_entry(entry))
ace71a19 KS	109	return false;
ace71a19 KS	110
af5cdaf8	111	pfn = swp_offset(entry);
0d665e7b KS	112	} else {
0d665e7b KS	113	if (!pte_present(*pvmw->pte))
ace71a19	114	return false;
0d665e7b KS	115
0d665e7b KS	116	pfn = pte_pfn(*pvmw->pte);
ace71a19 KS	117	}
ace71a19 KS	118
5b8d6e37	119	return pfn_is_match(pvmw->page, pfn);
ace71a19 KS	120	}
ace71a19 KS	121
a9a7504d HD	122	static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size)
	123	{
	124	pvmw->address = (pvmw->address + size) & ~(size - 1);
	125	if (!pvmw->address)
	126	pvmw->address = ULONG_MAX;
	127	}
	128
ace71a19 KS	129	/**
	130	* page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at
	131	* @pvmw->address
	132	* @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags
	133	* must be set. pmd, pte and ptl must be NULL.
	134	*
	135	* Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point
	136	* to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is
	137	* adjusted if needed (for PTE-mapped THPs).
	138	*
	139	* If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page
	140	* (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in
	141	* a loop to find all PTEs that map the THP.
	142	*
	143	* For HugeTLB pages, @pvmw->pte is set to the relevant page table entry
	144	* regardless of which page table level the page is mapped at. @pvmw->pmd is
	145	* NULL.
	146	*
baf2f90b	147	* Returns false if there are no more page table entries for the page in
ace71a19 KS	148	* the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped.
	149	*
	150	* If you need to stop the walk before page_vma_mapped_walk() returned false,
	151	* use page_vma_mapped_walk_done(). It will do the housekeeping.
	152	*/
	153	bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
	154	{
	155	struct mm_struct *mm = pvmw->vma->vm_mm;
	156	struct page *page = pvmw->page;
47446630	157	unsigned long end;
ace71a19	158	pgd_t *pgd;
c2febafc	159	p4d_t *p4d;
ace71a19	160	pud_t *pud;
a7b10095	161	pmd_t pmde;
ace71a19 KS	162
	163	/* The only possible pmd mapping has been handled on last iteration */
	164	if (pvmw->pmd && !pvmw->pte)
	165	return not_found(pvmw);
	166
f003c03b	167	if (unlikely(PageHuge(page))) {
6d0fd598 HD	168	/* The only possible mapping was handled on last iteration */
	169	if (pvmw->pte)
	170	return not_found(pvmw);
	171
ace71a19	172	/* when pud is not present, pte will be NULL */
a50b854e	173	pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
ace71a19 KS	174	if (!pvmw->pte)
	175	return false;
	176
	177	pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte);
	178	spin_lock(pvmw->ptl);
	179	if (!check_pte(pvmw))
	180	return not_found(pvmw);
	181	return true;
	182	}
6d0fd598	183
a765c417 HD	184	/*
	185	* Seek to next pte only makes sense for THP.
	186	* But more important than that optimization, is to filter out
	187	* any PageKsm page: whose page->index misleads vma_address()
	188	* and vma_address_end() to disaster.
	189	*/
	190	end = PageTransCompound(page) ?
	191	vma_address_end(page, pvmw->vma) :
	192	pvmw->address + PAGE_SIZE;
6d0fd598 HD	193	if (pvmw->pte)
6d0fd598 HD	194	goto next_pte;
ace71a19	195	restart:
a9a7504d	196	do {
b3807a91	197	pgd = pgd_offset(mm, pvmw->address);
a9a7504d HD	198	if (!pgd_present(*pgd)) {
	199	step_forward(pvmw, PGDIR_SIZE);
	200	continue;
	201	}
b3807a91	202	p4d = p4d_offset(pgd, pvmw->address);
a9a7504d HD	203	if (!p4d_present(*p4d)) {
	204	step_forward(pvmw, P4D_SIZE);
	205	continue;
	206	}
b3807a91	207	pud = pud_offset(p4d, pvmw->address);
a9a7504d HD	208	if (!pud_present(*pud)) {
	209	step_forward(pvmw, PUD_SIZE);
	210	continue;
	211	}
e2e1d407	212
b3807a91	213	pvmw->pmd = pmd_offset(pud, pvmw->address);
732ed558	214	/*
b3807a91 HD	215	* Make sure the pmd value isn't cached in a register by the
	216	* compiler and used as a stale value after we've observed a
	217	* subsequent update.
732ed558	218	*/
b3807a91 HD	219	pmde = READ_ONCE(*pvmw->pmd);
	220
	221	if (pmd_trans_huge(pmde) \|\| is_pmd_migration_entry(pmde)) {
	222	pvmw->ptl = pmd_lock(mm, pvmw->pmd);
	223	pmde = *pvmw->pmd;
	224	if (likely(pmd_trans_huge(pmde))) {
	225	if (pvmw->flags & PVMW_MIGRATION)
	226	return not_found(pvmw);
	227	if (pmd_page(pmde) != page)
	228	return not_found(pvmw);
	229	return true;
	230	}
	231	if (!pmd_present(pmde)) {
	232	swp_entry_t entry;
	233
	234	if (!thp_migration_supported() \|\|
	235	!(pvmw->flags & PVMW_MIGRATION))
	236	return not_found(pvmw);
	237	entry = pmd_to_swp_entry(pmde);
	238	if (!is_migration_entry(entry) \|\|
af5cdaf8	239	pfn_swap_entry_to_page(entry) != page)
b3807a91 HD	240	return not_found(pvmw);
	241	return true;
	242	}
	243	/* THP pmd was split under us: handle on pte level */
	244	spin_unlock(pvmw->ptl);
	245	pvmw->ptl = NULL;
	246	} else if (!pmd_present(pmde)) {
	247	/*
	248	* If PVMW_SYNC, take and drop THP pmd lock so that we
	249	* cannot return prematurely, while zap_huge_pmd() has
	250	* cleared *pmd but not decremented compound_mapcount().
	251	*/
	252	if ((pvmw->flags & PVMW_SYNC) &&
	253	PageTransCompound(page)) {
	254	spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);
732ed558	255
b3807a91 HD	256	spin_unlock(ptl);
b3807a91 HD	257	}
a9a7504d HD	258	step_forward(pvmw, PMD_SIZE);
a9a7504d HD	259	continue;
732ed558	260	}
b3807a91 HD	261	if (!map_pte(pvmw))
b3807a91 HD	262	goto next_pte;
47446630	263	this_pte:
ace71a19 KS	264	if (check_pte(pvmw))
ace71a19 KS	265	return true;
d75450ff	266	next_pte:
d75450ff	267	do {
ace71a19	268	pvmw->address += PAGE_SIZE;
494334e4	269	if (pvmw->address >= end)
ace71a19 KS	270	return not_found(pvmw);
ace71a19 KS	271	/* Did we cross page table boundary? */
44828248	272	if ((pvmw->address & (PMD_SIZE - PAGE_SIZE)) == 0) {
ace71a19 KS	273	if (pvmw->ptl) {
	274	spin_unlock(pvmw->ptl);
	275	pvmw->ptl = NULL;
	276	}
44828248 HD	277	pte_unmap(pvmw->pte);
44828248 HD	278	pvmw->pte = NULL;
ace71a19	279	goto restart;
ace71a19	280	}
44828248	281	pvmw->pte++;
a7a69d8b HD	282	if ((pvmw->flags & PVMW_SYNC) && !pvmw->ptl) {
	283	pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
	284	spin_lock(pvmw->ptl);
	285	}
ace71a19 KS	286	} while (pte_none(*pvmw->pte));
	287
	288	if (!pvmw->ptl) {
	289	pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
	290	spin_lock(pvmw->ptl);
	291	}
47446630	292	goto this_pte;
a9a7504d HD	293	} while (pvmw->address < end);
	294
	295	return false;
ace71a19	296	}
6a328a62 KS	297
	298	/**
	299	* page_mapped_in_vma - check whether a page is really mapped in a VMA
	300	* @page: the page to test
	301	* @vma: the VMA to test
	302	*
	303	* Returns 1 if the page is mapped into the page tables of the VMA, 0
	304	* if the page is not mapped into the page tables of this VMA. Only
	305	* valid for normal file or anonymous VMAs.
	306	*/
	307	int page_mapped_in_vma(struct page page, struct vm_area_struct vma)
	308	{
	309	struct page_vma_mapped_walk pvmw = {
	310	.page = page,
	311	.vma = vma,
	312	.flags = PVMW_SYNC,
	313	};
6a328a62	314
494334e4 HD	315	pvmw.address = vma_address(page, vma);
494334e4 HD	316	if (pvmw.address == -EFAULT)
6a328a62	317	return 0;
6a328a62 KS	318	if (!page_vma_mapped_walk(&pvmw))
	319	return 0;
	320	page_vma_mapped_walk_done(&pvmw);
	321	return 1;
	322	}