2 #include <linux/rmap.h>
3 #include <linux/hugetlb.h>
4 #include <linux/swap.h>
5 #include <linux/swapops.h>
9 static inline bool not_found(struct page_vma_mapped_walk
*pvmw
)
11 page_vma_mapped_walk_done(pvmw
);
15 static bool map_pte(struct page_vma_mapped_walk
*pvmw
)
17 pvmw
->pte
= pte_offset_map(pvmw
->pmd
, pvmw
->address
);
18 if (!(pvmw
->flags
& PVMW_SYNC
)) {
19 if (pvmw
->flags
& PVMW_MIGRATION
) {
20 if (!is_swap_pte(*pvmw
->pte
))
23 if (!pte_present(*pvmw
->pte
))
27 pvmw
->ptl
= pte_lockptr(pvmw
->vma
->vm_mm
, pvmw
->pmd
);
32 static bool check_pte(struct page_vma_mapped_walk
*pvmw
)
34 if (pvmw
->flags
& PVMW_MIGRATION
) {
35 #ifdef CONFIG_MIGRATION
37 if (!is_swap_pte(*pvmw
->pte
))
39 entry
= pte_to_swp_entry(*pvmw
->pte
);
41 if (!is_migration_entry(entry
))
43 if (migration_entry_to_page(entry
) - pvmw
->page
>=
44 hpage_nr_pages(pvmw
->page
)) {
47 if (migration_entry_to_page(entry
) < pvmw
->page
)
53 if (is_swap_pte(*pvmw
->pte
)) {
56 entry
= pte_to_swp_entry(*pvmw
->pte
);
57 if (is_device_private_entry(entry
) &&
58 device_private_entry_to_page(entry
) == pvmw
->page
)
62 if (!pte_present(*pvmw
->pte
))
65 /* THP can be referenced by any subpage */
66 if (pte_page(*pvmw
->pte
) - pvmw
->page
>=
67 hpage_nr_pages(pvmw
->page
)) {
70 if (pte_page(*pvmw
->pte
) < pvmw
->page
)
78 * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at
80 * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags
81 * must be set. pmd, pte and ptl must be NULL.
83 * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point
84 * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is
85 * adjusted if needed (for PTE-mapped THPs).
87 * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page
88 * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in
89 * a loop to find all PTEs that map the THP.
91 * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry
92 * regardless of which page table level the page is mapped at. @pvmw->pmd is
95 * Retruns false if there are no more page table entries for the page in
96 * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped.
98 * If you need to stop the walk before page_vma_mapped_walk() returned false,
99 * use page_vma_mapped_walk_done(). It will do the housekeeping.
101 bool page_vma_mapped_walk(struct page_vma_mapped_walk
*pvmw
)
103 struct mm_struct
*mm
= pvmw
->vma
->vm_mm
;
104 struct page
*page
= pvmw
->page
;
110 /* The only possible pmd mapping has been handled on last iteration */
111 if (pvmw
->pmd
&& !pvmw
->pte
)
112 return not_found(pvmw
);
117 if (unlikely(PageHuge(pvmw
->page
))) {
118 /* when pud is not present, pte will be NULL */
119 pvmw
->pte
= huge_pte_offset(mm
, pvmw
->address
,
120 PAGE_SIZE
<< compound_order(page
));
124 pvmw
->ptl
= huge_pte_lockptr(page_hstate(page
), mm
, pvmw
->pte
);
125 spin_lock(pvmw
->ptl
);
126 if (!check_pte(pvmw
))
127 return not_found(pvmw
);
131 pgd
= pgd_offset(mm
, pvmw
->address
);
132 if (!pgd_present(*pgd
))
134 p4d
= p4d_offset(pgd
, pvmw
->address
);
135 if (!p4d_present(*p4d
))
137 pud
= pud_offset(p4d
, pvmw
->address
);
138 if (!pud_present(*pud
))
140 pvmw
->pmd
= pmd_offset(pud
, pvmw
->address
);
142 * Make sure the pmd value isn't cached in a register by the
143 * compiler and used as a stale value after we've observed a
146 pmde
= READ_ONCE(*pvmw
->pmd
);
147 if (pmd_trans_huge(pmde
) || is_pmd_migration_entry(pmde
)) {
148 pvmw
->ptl
= pmd_lock(mm
, pvmw
->pmd
);
149 if (likely(pmd_trans_huge(*pvmw
->pmd
))) {
150 if (pvmw
->flags
& PVMW_MIGRATION
)
151 return not_found(pvmw
);
152 if (pmd_page(*pvmw
->pmd
) != page
)
153 return not_found(pvmw
);
155 } else if (!pmd_present(*pvmw
->pmd
)) {
156 if (thp_migration_supported()) {
157 if (!(pvmw
->flags
& PVMW_MIGRATION
))
158 return not_found(pvmw
);
159 if (is_migration_entry(pmd_to_swp_entry(*pvmw
->pmd
))) {
160 swp_entry_t entry
= pmd_to_swp_entry(*pvmw
->pmd
);
162 if (migration_entry_to_page(entry
) != page
)
163 return not_found(pvmw
);
167 return not_found(pvmw
);
169 /* THP pmd was split under us: handle on pte level */
170 spin_unlock(pvmw
->ptl
);
173 } else if (!pmd_present(pmde
)) {
182 /* Seek to next pte only makes sense for THP */
183 if (!PageTransHuge(pvmw
->page
) || PageHuge(pvmw
->page
))
184 return not_found(pvmw
);
186 pvmw
->address
+= PAGE_SIZE
;
187 if (pvmw
->address
>= pvmw
->vma
->vm_end
||
189 __vma_address(pvmw
->page
, pvmw
->vma
) +
190 hpage_nr_pages(pvmw
->page
) * PAGE_SIZE
)
191 return not_found(pvmw
);
192 /* Did we cross page table boundary? */
193 if (pvmw
->address
% PMD_SIZE
== 0) {
194 pte_unmap(pvmw
->pte
);
196 spin_unlock(pvmw
->ptl
);
203 } while (pte_none(*pvmw
->pte
));
206 pvmw
->ptl
= pte_lockptr(mm
, pvmw
->pmd
);
207 spin_lock(pvmw
->ptl
);
213 * page_mapped_in_vma - check whether a page is really mapped in a VMA
214 * @page: the page to test
215 * @vma: the VMA to test
217 * Returns 1 if the page is mapped into the page tables of the VMA, 0
218 * if the page is not mapped into the page tables of this VMA. Only
219 * valid for normal file or anonymous VMAs.
221 int page_mapped_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
223 struct page_vma_mapped_walk pvmw
= {
228 unsigned long start
, end
;
230 start
= __vma_address(page
, vma
);
231 end
= start
+ PAGE_SIZE
* (hpage_nr_pages(page
) - 1);
233 if (unlikely(end
< vma
->vm_start
|| start
>= vma
->vm_end
))
235 pvmw
.address
= max(start
, vma
->vm_start
);
236 if (!page_vma_mapped_walk(&pvmw
))
238 page_vma_mapped_walk_done(&pvmw
);