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ace71a19 KS |
1 | #include <linux/mm.h> |
2 | #include <linux/rmap.h> | |
3 | #include <linux/hugetlb.h> | |
4 | #include <linux/swap.h> | |
5 | #include <linux/swapops.h> | |
6 | ||
7 | #include "internal.h" | |
8 | ||
ace71a19 KS |
9 | static inline bool not_found(struct page_vma_mapped_walk *pvmw) |
10 | { | |
11 | page_vma_mapped_walk_done(pvmw); | |
12 | return false; | |
13 | } | |
14 | ||
15 | static bool map_pte(struct page_vma_mapped_walk *pvmw) | |
16 | { | |
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)) | |
21 | return false; | |
22 | } else { | |
23 | if (!pte_present(*pvmw->pte)) | |
24 | return false; | |
25 | } | |
26 | } | |
27 | pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd); | |
28 | spin_lock(pvmw->ptl); | |
29 | return true; | |
30 | } | |
31 | ||
32 | static bool check_pte(struct page_vma_mapped_walk *pvmw) | |
33 | { | |
34 | if (pvmw->flags & PVMW_MIGRATION) { | |
35 | #ifdef CONFIG_MIGRATION | |
36 | swp_entry_t entry; | |
37 | if (!is_swap_pte(*pvmw->pte)) | |
38 | return false; | |
39 | entry = pte_to_swp_entry(*pvmw->pte); | |
40 | if (!is_migration_entry(entry)) | |
41 | return false; | |
42 | if (migration_entry_to_page(entry) - pvmw->page >= | |
43 | hpage_nr_pages(pvmw->page)) { | |
44 | return false; | |
45 | } | |
46 | if (migration_entry_to_page(entry) < pvmw->page) | |
47 | return false; | |
48 | #else | |
49 | WARN_ON_ONCE(1); | |
50 | #endif | |
51 | } else { | |
52 | if (!pte_present(*pvmw->pte)) | |
53 | return false; | |
54 | ||
55 | /* THP can be referenced by any subpage */ | |
56 | if (pte_page(*pvmw->pte) - pvmw->page >= | |
57 | hpage_nr_pages(pvmw->page)) { | |
58 | return false; | |
59 | } | |
60 | if (pte_page(*pvmw->pte) < pvmw->page) | |
61 | return false; | |
62 | } | |
63 | ||
64 | return true; | |
65 | } | |
66 | ||
67 | /** | |
68 | * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at | |
69 | * @pvmw->address | |
70 | * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags | |
71 | * must be set. pmd, pte and ptl must be NULL. | |
72 | * | |
73 | * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point | |
74 | * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is | |
75 | * adjusted if needed (for PTE-mapped THPs). | |
76 | * | |
77 | * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page | |
78 | * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in | |
79 | * a loop to find all PTEs that map the THP. | |
80 | * | |
81 | * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry | |
82 | * regardless of which page table level the page is mapped at. @pvmw->pmd is | |
83 | * NULL. | |
84 | * | |
85 | * Retruns false if there are no more page table entries for the page in | |
86 | * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped. | |
87 | * | |
88 | * If you need to stop the walk before page_vma_mapped_walk() returned false, | |
89 | * use page_vma_mapped_walk_done(). It will do the housekeeping. | |
90 | */ | |
91 | bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) | |
92 | { | |
93 | struct mm_struct *mm = pvmw->vma->vm_mm; | |
94 | struct page *page = pvmw->page; | |
95 | pgd_t *pgd; | |
c2febafc | 96 | p4d_t *p4d; |
ace71a19 | 97 | pud_t *pud; |
745d3327 | 98 | pmd_t pmde; |
ace71a19 KS |
99 | |
100 | /* The only possible pmd mapping has been handled on last iteration */ | |
101 | if (pvmw->pmd && !pvmw->pte) | |
102 | return not_found(pvmw); | |
103 | ||
d75450ff | 104 | if (pvmw->pte) |
ace71a19 | 105 | goto next_pte; |
ace71a19 KS |
106 | |
107 | if (unlikely(PageHuge(pvmw->page))) { | |
108 | /* when pud is not present, pte will be NULL */ | |
7868a208 PA |
109 | pvmw->pte = huge_pte_offset(mm, pvmw->address, |
110 | PAGE_SIZE << compound_order(page)); | |
ace71a19 KS |
111 | if (!pvmw->pte) |
112 | return false; | |
113 | ||
114 | pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte); | |
115 | spin_lock(pvmw->ptl); | |
116 | if (!check_pte(pvmw)) | |
117 | return not_found(pvmw); | |
118 | return true; | |
119 | } | |
120 | restart: | |
121 | pgd = pgd_offset(mm, pvmw->address); | |
122 | if (!pgd_present(*pgd)) | |
123 | return false; | |
c2febafc KS |
124 | p4d = p4d_offset(pgd, pvmw->address); |
125 | if (!p4d_present(*p4d)) | |
126 | return false; | |
127 | pud = pud_offset(p4d, pvmw->address); | |
ace71a19 KS |
128 | if (!pud_present(*pud)) |
129 | return false; | |
130 | pvmw->pmd = pmd_offset(pud, pvmw->address); | |
745d3327 WD |
131 | /* |
132 | * Make sure the pmd value isn't cached in a register by the | |
133 | * compiler and used as a stale value after we've observed a | |
134 | * subsequent update. | |
135 | */ | |
136 | pmde = READ_ONCE(*pvmw->pmd); | |
137 | if (pmd_trans_huge(pmde)) { | |
ace71a19 KS |
138 | pvmw->ptl = pmd_lock(mm, pvmw->pmd); |
139 | if (!pmd_present(*pvmw->pmd)) | |
140 | return not_found(pvmw); | |
141 | if (likely(pmd_trans_huge(*pvmw->pmd))) { | |
142 | if (pvmw->flags & PVMW_MIGRATION) | |
143 | return not_found(pvmw); | |
144 | if (pmd_page(*pvmw->pmd) != page) | |
145 | return not_found(pvmw); | |
146 | return true; | |
147 | } else { | |
148 | /* THP pmd was split under us: handle on pte level */ | |
149 | spin_unlock(pvmw->ptl); | |
150 | pvmw->ptl = NULL; | |
151 | } | |
745d3327 WD |
152 | } else if (!pmd_present(pmde)) { |
153 | return false; | |
ace71a19 KS |
154 | } |
155 | if (!map_pte(pvmw)) | |
156 | goto next_pte; | |
157 | while (1) { | |
158 | if (check_pte(pvmw)) | |
159 | return true; | |
d75450ff HD |
160 | next_pte: |
161 | /* Seek to next pte only makes sense for THP */ | |
162 | if (!PageTransHuge(pvmw->page) || PageHuge(pvmw->page)) | |
163 | return not_found(pvmw); | |
164 | do { | |
ace71a19 | 165 | pvmw->address += PAGE_SIZE; |
d75450ff HD |
166 | if (pvmw->address >= pvmw->vma->vm_end || |
167 | pvmw->address >= | |
ace71a19 KS |
168 | __vma_address(pvmw->page, pvmw->vma) + |
169 | hpage_nr_pages(pvmw->page) * PAGE_SIZE) | |
170 | return not_found(pvmw); | |
171 | /* Did we cross page table boundary? */ | |
172 | if (pvmw->address % PMD_SIZE == 0) { | |
173 | pte_unmap(pvmw->pte); | |
174 | if (pvmw->ptl) { | |
175 | spin_unlock(pvmw->ptl); | |
176 | pvmw->ptl = NULL; | |
177 | } | |
178 | goto restart; | |
179 | } else { | |
180 | pvmw->pte++; | |
181 | } | |
182 | } while (pte_none(*pvmw->pte)); | |
183 | ||
184 | if (!pvmw->ptl) { | |
185 | pvmw->ptl = pte_lockptr(mm, pvmw->pmd); | |
186 | spin_lock(pvmw->ptl); | |
187 | } | |
188 | } | |
189 | } | |
6a328a62 KS |
190 | |
191 | /** | |
192 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
193 | * @page: the page to test | |
194 | * @vma: the VMA to test | |
195 | * | |
196 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
197 | * if the page is not mapped into the page tables of this VMA. Only | |
198 | * valid for normal file or anonymous VMAs. | |
199 | */ | |
200 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) | |
201 | { | |
202 | struct page_vma_mapped_walk pvmw = { | |
203 | .page = page, | |
204 | .vma = vma, | |
205 | .flags = PVMW_SYNC, | |
206 | }; | |
207 | unsigned long start, end; | |
208 | ||
209 | start = __vma_address(page, vma); | |
210 | end = start + PAGE_SIZE * (hpage_nr_pages(page) - 1); | |
211 | ||
212 | if (unlikely(end < vma->vm_start || start >= vma->vm_end)) | |
213 | return 0; | |
214 | pvmw.address = max(start, vma->vm_start); | |
215 | if (!page_vma_mapped_walk(&pvmw)) | |
216 | return 0; | |
217 | page_vma_mapped_walk_done(&pvmw); | |
218 | return 1; | |
219 | } |