2 #include <linux/rmap.h>
3 #include <linux/hugetlb.h>
4 #include <linux/swap.h>
5 #include <linux/swapops.h>
9 static inline bool check_pmd(struct page_vma_mapped_walk *pvmw)
13 * Make sure we don't re-load pmd between present and !trans_huge check.
14 * We need a consistent view.
16 pmde = READ_ONCE(*pvmw->pmd);
17 return pmd_present(pmde) && !pmd_trans_huge(pmde);
20 static inline bool not_found(struct page_vma_mapped_walk *pvmw)
22 page_vma_mapped_walk_done(pvmw);
26 static bool map_pte(struct page_vma_mapped_walk *pvmw)
28 pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
29 if (!(pvmw->flags & PVMW_SYNC)) {
30 if (pvmw->flags & PVMW_MIGRATION) {
31 if (!is_swap_pte(*pvmw->pte))
34 if (!pte_present(*pvmw->pte))
38 pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
43 static bool check_pte(struct page_vma_mapped_walk *pvmw)
45 if (pvmw->flags & PVMW_MIGRATION) {
46 #ifdef CONFIG_MIGRATION
48 if (!is_swap_pte(*pvmw->pte))
50 entry = pte_to_swp_entry(*pvmw->pte);
52 if (!is_migration_entry(entry))
54 if (migration_entry_to_page(entry) - pvmw->page >=
55 hpage_nr_pages(pvmw->page)) {
58 if (migration_entry_to_page(entry) < pvmw->page)
64 if (is_swap_pte(*pvmw->pte)) {
67 entry = pte_to_swp_entry(*pvmw->pte);
68 if (is_device_private_entry(entry) &&
69 device_private_entry_to_page(entry) == pvmw->page)
73 if (!pte_present(*pvmw->pte))
76 /* THP can be referenced by any subpage */
77 if (pte_page(*pvmw->pte) - pvmw->page >=
78 hpage_nr_pages(pvmw->page)) {
81 if (pte_page(*pvmw->pte) < pvmw->page)
89 * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at
91 * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags
92 * must be set. pmd, pte and ptl must be NULL.
94 * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point
95 * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is
96 * adjusted if needed (for PTE-mapped THPs).
98 * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page
99 * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in
100 * a loop to find all PTEs that map the THP.
102 * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry
103 * regardless of which page table level the page is mapped at. @pvmw->pmd is
106 * Retruns false if there are no more page table entries for the page in
107 * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped.
109 * If you need to stop the walk before page_vma_mapped_walk() returned false,
110 * use page_vma_mapped_walk_done(). It will do the housekeeping.
112 bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
114 struct mm_struct *mm = pvmw->vma->vm_mm;
115 struct page *page = pvmw->page;
120 /* The only possible pmd mapping has been handled on last iteration */
121 if (pvmw->pmd && !pvmw->pte)
122 return not_found(pvmw);
127 if (unlikely(PageHuge(pvmw->page))) {
128 /* when pud is not present, pte will be NULL */
129 pvmw->pte = huge_pte_offset(mm, pvmw->address,
130 PAGE_SIZE << compound_order(page));
134 pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte);
135 spin_lock(pvmw->ptl);
136 if (!check_pte(pvmw))
137 return not_found(pvmw);
141 pgd = pgd_offset(mm, pvmw->address);
142 if (!pgd_present(*pgd))
144 p4d = p4d_offset(pgd, pvmw->address);
145 if (!p4d_present(*p4d))
147 pud = pud_offset(p4d, pvmw->address);
148 if (!pud_present(*pud))
150 pvmw->pmd = pmd_offset(pud, pvmw->address);
151 if (pmd_trans_huge(*pvmw->pmd) || is_pmd_migration_entry(*pvmw->pmd)) {
152 pvmw->ptl = pmd_lock(mm, pvmw->pmd);
153 if (likely(pmd_trans_huge(*pvmw->pmd))) {
154 if (pvmw->flags & PVMW_MIGRATION)
155 return not_found(pvmw);
156 if (pmd_page(*pvmw->pmd) != page)
157 return not_found(pvmw);
159 } else if (!pmd_present(*pvmw->pmd)) {
160 if (thp_migration_supported()) {
161 if (!(pvmw->flags & PVMW_MIGRATION))
162 return not_found(pvmw);
163 if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
164 swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
166 if (migration_entry_to_page(entry) != page)
167 return not_found(pvmw);
171 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
172 return not_found(pvmw);
174 /* THP pmd was split under us: handle on pte level */
175 spin_unlock(pvmw->ptl);
179 if (!check_pmd(pvmw))
188 /* Seek to next pte only makes sense for THP */
189 if (!PageTransHuge(pvmw->page) || PageHuge(pvmw->page))
190 return not_found(pvmw);
192 pvmw->address += PAGE_SIZE;
193 if (pvmw->address >= pvmw->vma->vm_end ||
195 __vma_address(pvmw->page, pvmw->vma) +
196 hpage_nr_pages(pvmw->page) * PAGE_SIZE)
197 return not_found(pvmw);
198 /* Did we cross page table boundary? */
199 if (pvmw->address % PMD_SIZE == 0) {
200 pte_unmap(pvmw->pte);
202 spin_unlock(pvmw->ptl);
209 } while (pte_none(*pvmw->pte));
212 pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
213 spin_lock(pvmw->ptl);
219 * page_mapped_in_vma - check whether a page is really mapped in a VMA
220 * @page: the page to test
221 * @vma: the VMA to test
223 * Returns 1 if the page is mapped into the page tables of the VMA, 0
224 * if the page is not mapped into the page tables of this VMA. Only
225 * valid for normal file or anonymous VMAs.
227 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
229 struct page_vma_mapped_walk pvmw = {
234 unsigned long start, end;
236 start = __vma_address(page, vma);
237 end = start + PAGE_SIZE * (hpage_nr_pages(page) - 1);
239 if (unlikely(end < vma->vm_start || start >= vma->vm_end))
241 pvmw.address = max(start, vma->vm_start);
242 if (!page_vma_mapped_walk(&pvmw))
244 page_vma_mapped_walk_done(&pvmw);