318 строки
8.6 KiB
C
318 строки
8.6 KiB
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;
|
|
}
|
|
|
|
/**
|
|
* 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 - 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)
|
|
{
|
|
pvmw->address = (pvmw->address + size) & ~(size - 1);
|
|
if (!pvmw->address)
|
|
pvmw->address = ULONG_MAX;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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 vm_area_struct *vma = pvmw->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
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(is_vm_hugetlb_page(vma))) {
|
|
struct hstate *hstate = hstate_vma(vma);
|
|
unsigned long size = huge_page_size(hstate);
|
|
/* 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, size);
|
|
if (!pvmw->pte)
|
|
return false;
|
|
|
|
pvmw->ptl = huge_pte_lockptr(hstate, mm, pvmw->pte);
|
|
spin_lock(pvmw->ptl);
|
|
if (!check_pte(pvmw))
|
|
return not_found(pvmw);
|
|
return true;
|
|
}
|
|
|
|
end = vma_address_end(pvmw);
|
|
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) ||
|
|
(pmd_present(pmde) && pmd_devmap(pmde))) {
|
|
pvmw->ptl = pmd_lock(mm, pvmw->pmd);
|
|
pmde = *pvmw->pmd;
|
|
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) ||
|
|
!check_pmd(swp_offset(entry), pvmw))
|
|
return not_found(pvmw);
|
|
return true;
|
|
}
|
|
if (likely(pmd_trans_huge(pmde) || pmd_devmap(pmde))) {
|
|
if (pvmw->flags & PVMW_MIGRATION)
|
|
return not_found(pvmw);
|
|
if (!check_pmd(pmd_pfn(pmde), pvmw))
|
|
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) &&
|
|
transparent_hugepage_active(vma) &&
|
|
(pvmw->nr_pages >= HPAGE_PMD_NR)) {
|
|
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 = {
|
|
.pfn = page_to_pfn(page),
|
|
.nr_pages = 1,
|
|
.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;
|
|
}
|