Commit 2aff7a47 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm: Convert page_vma_mapped_walk to work on PFNs 



page_mapped_in_vma() really just wants to walk one page, but as the
code stands, if passed the head page of a compound page, it will
walk every page in the compound page.  Extract pfn/nr_pages/pgoff
from the struct page early, so they can be overridden by
page_mapped_in_vma().

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent aef13dec

include/linux/hugetlb.h

+5 −0
Original line number Diff line number Diff line
@@ -970,6 +970,11 @@ static inline struct hstate *page_hstate(struct page *page) 
	return NULL;

}



static inline struct hstate *size_to_hstate(unsigned long size)

{

	return NULL;

}



static inline unsigned long huge_page_size(struct hstate *h)

{

	return PAGE_SIZE;

include/linux/rmap.h

+12 −5
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/rwsem.h>

#include <linux/memcontrol.h>

#include <linux/highmem.h>

#include <linux/pagemap.h>



/*

 * The anon_vma heads a list of private "related" vmas, to scan if
@@ -201,11 +202,13 @@ int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, 


/* Avoid racy checks */

#define PVMW_SYNC		(1 << 0)

/* Look for migarion entries rather than present PTEs */

/* Look for migration entries rather than present PTEs */

#define PVMW_MIGRATION		(1 << 1)



struct page_vma_mapped_walk {

	struct page *page;

	unsigned long pfn;

	unsigned long nr_pages;

	pgoff_t pgoff;

	struct vm_area_struct *vma;

	unsigned long address;

	pmd_t *pmd;
@@ -216,7 +219,9 @@ struct page_vma_mapped_walk { 


#define DEFINE_PAGE_VMA_WALK(name, _page, _vma, _address, _flags)	\

	struct page_vma_mapped_walk name = {				\

		.page = _page,						\

		.pfn = page_to_pfn(_page),				\

		.nr_pages = compound_nr(page),				\

		.pgoff = page_to_pgoff(page),				\

		.vma = _vma,						\

		.address = _address,					\

		.flags = _flags,					\
@@ -224,7 +229,9 @@ struct page_vma_mapped_walk { 


#define DEFINE_FOLIO_VMA_WALK(name, _folio, _vma, _address, _flags)	\

	struct page_vma_mapped_walk name = {				\

		.page = &_folio->page,					\

		.pfn = folio_pfn(_folio),				\

		.nr_pages = folio_nr_pages(_folio),			\

		.pgoff = folio_pgoff(_folio),				\

		.vma = _vma,						\

		.address = _address,					\

		.flags = _flags,					\
@@ -233,7 +240,7 @@ struct page_vma_mapped_walk { 
static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)

{

	/* HugeTLB pte is set to the relevant page table entry without pte_mapped. */

	if (pvmw->pte && !PageHuge(pvmw->page))

	if (pvmw->pte && !is_vm_hugetlb_page(pvmw->vma))

		pte_unmap(pvmw->pte);

	if (pvmw->ptl)

		spin_unlock(pvmw->ptl);

mm/internal.h

+9 −6
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/fs.h>

#include <linux/mm.h>

#include <linux/pagemap.h>

#include <linux/rmap.h>

#include <linux/tracepoint-defs.h>



struct folio_batch;
@@ -475,18 +476,20 @@ vma_address(struct page *page, struct vm_area_struct *vma) 
}



/*

 * Then at what user virtual address will none of the page be found in vma?

 * Then at what user virtual address will none of the range be found in vma?

 * Assumes that vma_address() already returned a good starting address.

 * If page is a compound head, the entire compound page is considered.

 */

static inline unsigned long

vma_address_end(struct page *page, struct vm_area_struct *vma)

static inline unsigned long vma_address_end(struct page_vma_mapped_walk *pvmw)

{

	struct vm_area_struct *vma = pvmw->vma;

	pgoff_t pgoff;

	unsigned long address;



	VM_BUG_ON_PAGE(PageKsm(page), page);	/* KSM page->index unusable */

	pgoff = page_to_pgoff(page) + compound_nr(page);

	/* Common case, plus ->pgoff is invalid for KSM */

	if (pvmw->nr_pages == 1)

		return pvmw->address + PAGE_SIZE;



	pgoff = pvmw->pgoff + pvmw->nr_pages;

	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);

	/* Check for address beyond vma (or wrapped through 0?) */

	if (address < vma->vm_start || address > vma->vm_end)

mm/migrate.c

+3 −2
Original line number Diff line number Diff line
@@ -174,7 +174,8 @@ void putback_movable_pages(struct list_head *l) 
static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,

				 unsigned long addr, void *old)

{

	DEFINE_PAGE_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION);

	DEFINE_PAGE_VMA_WALK(pvmw, (struct page *)old, vma, addr,

				PVMW_SYNC | PVMW_MIGRATION);

	struct page *new;

	pte_t pte;

	swp_entry_t entry;
@@ -184,7 +185,7 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma, 
		if (PageKsm(page))

			new = page;

		else

			new = page - pvmw.page->index +

			new = page - pvmw.pgoff +

				linear_page_index(vma, pvmw.address);



#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION

mm/page_vma_mapped.c

+26 −32
Original line number Diff line number Diff line
@@ -53,18 +53,6 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw) 
	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
@@ -116,7 +104,17 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw) 
		pfn = pte_pfn(*pvmw->pte);

	}



	return pfn_is_match(pvmw->page, pfn);

	return (pfn - pvmw->pfn) < pvmw->nr_pages;

}



/* Returns true if the two ranges overlap.  Careful to not overflow. */

static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw)

{

	if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)

		return false;

	if (pfn > pvmw->pfn + pvmw->nr_pages - 1)

		return false;

	return true;

}



static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size)
@@ -127,7 +125,7 @@ static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) 
}



/**

 * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at

 * page_vma_mapped_walk - check if @pvmw->pfn 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.
@@ -152,8 +150,8 @@ static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) 
 */

bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)

{

	struct mm_struct *mm = pvmw->vma->vm_mm;

	struct page *page = pvmw->page;

	struct vm_area_struct *vma = pvmw->vma;

	struct mm_struct *mm = vma->vm_mm;

	unsigned long end;

	pgd_t *pgd;

	p4d_t *p4d;
@@ -164,32 +162,26 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) 
	if (pvmw->pmd && !pvmw->pte)

		return not_found(pvmw);



	if (unlikely(PageHuge(page))) {

	if (unlikely(is_vm_hugetlb_page(vma))) {

		unsigned long size = pvmw->nr_pages * PAGE_SIZE;

		/* 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));

		pvmw->pte = huge_pte_offset(mm, pvmw->address, size);

		if (!pvmw->pte)

			return false;



		pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte);

		pvmw->ptl = huge_pte_lockptr(size_to_hstate(size), 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;

	end = vma_address_end(pvmw);

	if (pvmw->pte)

		goto next_pte;

restart:
@@ -224,7 +216,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) 
			if (likely(pmd_trans_huge(pmde))) {

				if (pvmw->flags & PVMW_MIGRATION)

					return not_found(pvmw);

				if (pmd_page(pmde) != page)

				if (!check_pmd(pmd_pfn(pmde), pvmw))

					return not_found(pvmw);

				return true;

			}
@@ -236,7 +228,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) 
					return not_found(pvmw);

				entry = pmd_to_swp_entry(pmde);

				if (!is_migration_entry(entry) ||

				    pfn_swap_entry_to_page(entry) != page)

				    !check_pmd(swp_offset(entry), pvmw))

					return not_found(pvmw);

				return true;

			}
@@ -250,7 +242,8 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) 
			 * cleared *pmd but not decremented compound_mapcount().

			 */

			if ((pvmw->flags & PVMW_SYNC) &&

			    PageTransCompound(page)) {

			    transparent_hugepage_active(vma) &&

			    (pvmw->nr_pages >= HPAGE_PMD_NR)) {

				spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);



				spin_unlock(ptl);
@@ -307,7 +300,8 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) 
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)

{

	struct page_vma_mapped_walk pvmw = {

		.page = page,

		.pfn = page_to_pfn(page),

		.nr_pages = 1,

		.vma = vma,

		.flags = PVMW_SYNC,

	};