d4847026d4b1d24ebfe200ae72589b12c58cc742
[sfrench/cifs-2.6.git] / mm / huge_memory.c
1 /*
2  *  Copyright (C) 2009  Red Hat, Inc.
3  *
4  *  This work is licensed under the terms of the GNU GPL, version 2. See
5  *  the COPYING file in the top-level directory.
6  */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/mm.h>
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
36 #include <linux/numa.h>
37
38 #include <asm/tlb.h>
39 #include <asm/pgalloc.h>
40 #include "internal.h"
41
42 /*
43  * By default, transparent hugepage support is disabled in order to avoid
44  * risking an increased memory footprint for applications that are not
45  * guaranteed to benefit from it. When transparent hugepage support is
46  * enabled, it is for all mappings, and khugepaged scans all mappings.
47  * Defrag is invoked by khugepaged hugepage allocations and by page faults
48  * for all hugepage allocations.
49  */
50 unsigned long transparent_hugepage_flags __read_mostly =
51 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
52         (1<<TRANSPARENT_HUGEPAGE_FLAG)|
53 #endif
54 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
55         (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
56 #endif
57         (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
58         (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
59         (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60
61 static struct shrinker deferred_split_shrinker;
62
63 static atomic_t huge_zero_refcount;
64 struct page *huge_zero_page __read_mostly;
65
66 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
67 {
68         if (vma_is_anonymous(vma))
69                 return __transparent_hugepage_enabled(vma);
70         if (vma_is_shmem(vma) && shmem_huge_enabled(vma))
71                 return __transparent_hugepage_enabled(vma);
72
73         return false;
74 }
75
76 static struct page *get_huge_zero_page(void)
77 {
78         struct page *zero_page;
79 retry:
80         if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
81                 return READ_ONCE(huge_zero_page);
82
83         zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
84                         HPAGE_PMD_ORDER);
85         if (!zero_page) {
86                 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
87                 return NULL;
88         }
89         count_vm_event(THP_ZERO_PAGE_ALLOC);
90         preempt_disable();
91         if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
92                 preempt_enable();
93                 __free_pages(zero_page, compound_order(zero_page));
94                 goto retry;
95         }
96
97         /* We take additional reference here. It will be put back by shrinker */
98         atomic_set(&huge_zero_refcount, 2);
99         preempt_enable();
100         return READ_ONCE(huge_zero_page);
101 }
102
103 static void put_huge_zero_page(void)
104 {
105         /*
106          * Counter should never go to zero here. Only shrinker can put
107          * last reference.
108          */
109         BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
110 }
111
112 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
113 {
114         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
115                 return READ_ONCE(huge_zero_page);
116
117         if (!get_huge_zero_page())
118                 return NULL;
119
120         if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
121                 put_huge_zero_page();
122
123         return READ_ONCE(huge_zero_page);
124 }
125
126 void mm_put_huge_zero_page(struct mm_struct *mm)
127 {
128         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
129                 put_huge_zero_page();
130 }
131
132 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
133                                         struct shrink_control *sc)
134 {
135         /* we can free zero page only if last reference remains */
136         return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
137 }
138
139 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
140                                        struct shrink_control *sc)
141 {
142         if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
143                 struct page *zero_page = xchg(&huge_zero_page, NULL);
144                 BUG_ON(zero_page == NULL);
145                 __free_pages(zero_page, compound_order(zero_page));
146                 return HPAGE_PMD_NR;
147         }
148
149         return 0;
150 }
151
152 static struct shrinker huge_zero_page_shrinker = {
153         .count_objects = shrink_huge_zero_page_count,
154         .scan_objects = shrink_huge_zero_page_scan,
155         .seeks = DEFAULT_SEEKS,
156 };
157
158 #ifdef CONFIG_SYSFS
159 static ssize_t enabled_show(struct kobject *kobj,
160                             struct kobj_attribute *attr, char *buf)
161 {
162         if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
163                 return sprintf(buf, "[always] madvise never\n");
164         else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
165                 return sprintf(buf, "always [madvise] never\n");
166         else
167                 return sprintf(buf, "always madvise [never]\n");
168 }
169
170 static ssize_t enabled_store(struct kobject *kobj,
171                              struct kobj_attribute *attr,
172                              const char *buf, size_t count)
173 {
174         ssize_t ret = count;
175
176         if (!memcmp("always", buf,
177                     min(sizeof("always")-1, count))) {
178                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
179                 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
180         } else if (!memcmp("madvise", buf,
181                            min(sizeof("madvise")-1, count))) {
182                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
183                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
184         } else if (!memcmp("never", buf,
185                            min(sizeof("never")-1, count))) {
186                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
187                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
188         } else
189                 ret = -EINVAL;
190
191         if (ret > 0) {
192                 int err = start_stop_khugepaged();
193                 if (err)
194                         ret = err;
195         }
196         return ret;
197 }
198 static struct kobj_attribute enabled_attr =
199         __ATTR(enabled, 0644, enabled_show, enabled_store);
200
201 ssize_t single_hugepage_flag_show(struct kobject *kobj,
202                                 struct kobj_attribute *attr, char *buf,
203                                 enum transparent_hugepage_flag flag)
204 {
205         return sprintf(buf, "%d\n",
206                        !!test_bit(flag, &transparent_hugepage_flags));
207 }
208
209 ssize_t single_hugepage_flag_store(struct kobject *kobj,
210                                  struct kobj_attribute *attr,
211                                  const char *buf, size_t count,
212                                  enum transparent_hugepage_flag flag)
213 {
214         unsigned long value;
215         int ret;
216
217         ret = kstrtoul(buf, 10, &value);
218         if (ret < 0)
219                 return ret;
220         if (value > 1)
221                 return -EINVAL;
222
223         if (value)
224                 set_bit(flag, &transparent_hugepage_flags);
225         else
226                 clear_bit(flag, &transparent_hugepage_flags);
227
228         return count;
229 }
230
231 static ssize_t defrag_show(struct kobject *kobj,
232                            struct kobj_attribute *attr, char *buf)
233 {
234         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
235                 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
236         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
237                 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
238         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
239                 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
240         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
241                 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
242         return sprintf(buf, "always defer defer+madvise madvise [never]\n");
243 }
244
245 static ssize_t defrag_store(struct kobject *kobj,
246                             struct kobj_attribute *attr,
247                             const char *buf, size_t count)
248 {
249         if (!memcmp("always", buf,
250                     min(sizeof("always")-1, count))) {
251                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
252                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
253                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
254                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
255         } else if (!memcmp("defer+madvise", buf,
256                     min(sizeof("defer+madvise")-1, count))) {
257                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
258                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
259                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
260                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
261         } else if (!memcmp("defer", buf,
262                     min(sizeof("defer")-1, count))) {
263                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
264                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
265                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
266                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
267         } else if (!memcmp("madvise", buf,
268                            min(sizeof("madvise")-1, count))) {
269                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
270                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
271                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
272                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
273         } else if (!memcmp("never", buf,
274                            min(sizeof("never")-1, count))) {
275                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
276                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
277                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
278                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
279         } else
280                 return -EINVAL;
281
282         return count;
283 }
284 static struct kobj_attribute defrag_attr =
285         __ATTR(defrag, 0644, defrag_show, defrag_store);
286
287 static ssize_t use_zero_page_show(struct kobject *kobj,
288                 struct kobj_attribute *attr, char *buf)
289 {
290         return single_hugepage_flag_show(kobj, attr, buf,
291                                 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
292 }
293 static ssize_t use_zero_page_store(struct kobject *kobj,
294                 struct kobj_attribute *attr, const char *buf, size_t count)
295 {
296         return single_hugepage_flag_store(kobj, attr, buf, count,
297                                  TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
298 }
299 static struct kobj_attribute use_zero_page_attr =
300         __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
301
302 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
303                 struct kobj_attribute *attr, char *buf)
304 {
305         return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
306 }
307 static struct kobj_attribute hpage_pmd_size_attr =
308         __ATTR_RO(hpage_pmd_size);
309
310 #ifdef CONFIG_DEBUG_VM
311 static ssize_t debug_cow_show(struct kobject *kobj,
312                                 struct kobj_attribute *attr, char *buf)
313 {
314         return single_hugepage_flag_show(kobj, attr, buf,
315                                 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
316 }
317 static ssize_t debug_cow_store(struct kobject *kobj,
318                                struct kobj_attribute *attr,
319                                const char *buf, size_t count)
320 {
321         return single_hugepage_flag_store(kobj, attr, buf, count,
322                                  TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
323 }
324 static struct kobj_attribute debug_cow_attr =
325         __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
326 #endif /* CONFIG_DEBUG_VM */
327
328 static struct attribute *hugepage_attr[] = {
329         &enabled_attr.attr,
330         &defrag_attr.attr,
331         &use_zero_page_attr.attr,
332         &hpage_pmd_size_attr.attr,
333 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
334         &shmem_enabled_attr.attr,
335 #endif
336 #ifdef CONFIG_DEBUG_VM
337         &debug_cow_attr.attr,
338 #endif
339         NULL,
340 };
341
342 static const struct attribute_group hugepage_attr_group = {
343         .attrs = hugepage_attr,
344 };
345
346 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
347 {
348         int err;
349
350         *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
351         if (unlikely(!*hugepage_kobj)) {
352                 pr_err("failed to create transparent hugepage kobject\n");
353                 return -ENOMEM;
354         }
355
356         err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
357         if (err) {
358                 pr_err("failed to register transparent hugepage group\n");
359                 goto delete_obj;
360         }
361
362         err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
363         if (err) {
364                 pr_err("failed to register transparent hugepage group\n");
365                 goto remove_hp_group;
366         }
367
368         return 0;
369
370 remove_hp_group:
371         sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
372 delete_obj:
373         kobject_put(*hugepage_kobj);
374         return err;
375 }
376
377 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
378 {
379         sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
380         sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
381         kobject_put(hugepage_kobj);
382 }
383 #else
384 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
385 {
386         return 0;
387 }
388
389 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
390 {
391 }
392 #endif /* CONFIG_SYSFS */
393
394 static int __init hugepage_init(void)
395 {
396         int err;
397         struct kobject *hugepage_kobj;
398
399         if (!has_transparent_hugepage()) {
400                 transparent_hugepage_flags = 0;
401                 return -EINVAL;
402         }
403
404         /*
405          * hugepages can't be allocated by the buddy allocator
406          */
407         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
408         /*
409          * we use page->mapping and page->index in second tail page
410          * as list_head: assuming THP order >= 2
411          */
412         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
413
414         err = hugepage_init_sysfs(&hugepage_kobj);
415         if (err)
416                 goto err_sysfs;
417
418         err = khugepaged_init();
419         if (err)
420                 goto err_slab;
421
422         err = register_shrinker(&huge_zero_page_shrinker);
423         if (err)
424                 goto err_hzp_shrinker;
425         err = register_shrinker(&deferred_split_shrinker);
426         if (err)
427                 goto err_split_shrinker;
428
429         /*
430          * By default disable transparent hugepages on smaller systems,
431          * where the extra memory used could hurt more than TLB overhead
432          * is likely to save.  The admin can still enable it through /sys.
433          */
434         if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
435                 transparent_hugepage_flags = 0;
436                 return 0;
437         }
438
439         err = start_stop_khugepaged();
440         if (err)
441                 goto err_khugepaged;
442
443         return 0;
444 err_khugepaged:
445         unregister_shrinker(&deferred_split_shrinker);
446 err_split_shrinker:
447         unregister_shrinker(&huge_zero_page_shrinker);
448 err_hzp_shrinker:
449         khugepaged_destroy();
450 err_slab:
451         hugepage_exit_sysfs(hugepage_kobj);
452 err_sysfs:
453         return err;
454 }
455 subsys_initcall(hugepage_init);
456
457 static int __init setup_transparent_hugepage(char *str)
458 {
459         int ret = 0;
460         if (!str)
461                 goto out;
462         if (!strcmp(str, "always")) {
463                 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
464                         &transparent_hugepage_flags);
465                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
466                           &transparent_hugepage_flags);
467                 ret = 1;
468         } else if (!strcmp(str, "madvise")) {
469                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
470                           &transparent_hugepage_flags);
471                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
472                         &transparent_hugepage_flags);
473                 ret = 1;
474         } else if (!strcmp(str, "never")) {
475                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
476                           &transparent_hugepage_flags);
477                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
478                           &transparent_hugepage_flags);
479                 ret = 1;
480         }
481 out:
482         if (!ret)
483                 pr_warn("transparent_hugepage= cannot parse, ignored\n");
484         return ret;
485 }
486 __setup("transparent_hugepage=", setup_transparent_hugepage);
487
488 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
489 {
490         if (likely(vma->vm_flags & VM_WRITE))
491                 pmd = pmd_mkwrite(pmd);
492         return pmd;
493 }
494
495 static inline struct list_head *page_deferred_list(struct page *page)
496 {
497         /* ->lru in the tail pages is occupied by compound_head. */
498         return &page[2].deferred_list;
499 }
500
501 void prep_transhuge_page(struct page *page)
502 {
503         /*
504          * we use page->mapping and page->indexlru in second tail page
505          * as list_head: assuming THP order >= 2
506          */
507
508         INIT_LIST_HEAD(page_deferred_list(page));
509         set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
510 }
511
512 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
513                 loff_t off, unsigned long flags, unsigned long size)
514 {
515         unsigned long addr;
516         loff_t off_end = off + len;
517         loff_t off_align = round_up(off, size);
518         unsigned long len_pad;
519
520         if (off_end <= off_align || (off_end - off_align) < size)
521                 return 0;
522
523         len_pad = len + size;
524         if (len_pad < len || (off + len_pad) < off)
525                 return 0;
526
527         addr = current->mm->get_unmapped_area(filp, 0, len_pad,
528                                               off >> PAGE_SHIFT, flags);
529         if (IS_ERR_VALUE(addr))
530                 return 0;
531
532         addr += (off - addr) & (size - 1);
533         return addr;
534 }
535
536 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
537                 unsigned long len, unsigned long pgoff, unsigned long flags)
538 {
539         loff_t off = (loff_t)pgoff << PAGE_SHIFT;
540
541         if (addr)
542                 goto out;
543         if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
544                 goto out;
545
546         addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
547         if (addr)
548                 return addr;
549
550  out:
551         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
552 }
553 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
554
555 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
556                         struct page *page, gfp_t gfp)
557 {
558         struct vm_area_struct *vma = vmf->vma;
559         struct mem_cgroup *memcg;
560         pgtable_t pgtable;
561         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
562         vm_fault_t ret = 0;
563
564         VM_BUG_ON_PAGE(!PageCompound(page), page);
565
566         if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
567                 put_page(page);
568                 count_vm_event(THP_FAULT_FALLBACK);
569                 return VM_FAULT_FALLBACK;
570         }
571
572         pgtable = pte_alloc_one(vma->vm_mm);
573         if (unlikely(!pgtable)) {
574                 ret = VM_FAULT_OOM;
575                 goto release;
576         }
577
578         clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
579         /*
580          * The memory barrier inside __SetPageUptodate makes sure that
581          * clear_huge_page writes become visible before the set_pmd_at()
582          * write.
583          */
584         __SetPageUptodate(page);
585
586         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
587         if (unlikely(!pmd_none(*vmf->pmd))) {
588                 goto unlock_release;
589         } else {
590                 pmd_t entry;
591
592                 ret = check_stable_address_space(vma->vm_mm);
593                 if (ret)
594                         goto unlock_release;
595
596                 /* Deliver the page fault to userland */
597                 if (userfaultfd_missing(vma)) {
598                         vm_fault_t ret2;
599
600                         spin_unlock(vmf->ptl);
601                         mem_cgroup_cancel_charge(page, memcg, true);
602                         put_page(page);
603                         pte_free(vma->vm_mm, pgtable);
604                         ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
605                         VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
606                         return ret2;
607                 }
608
609                 entry = mk_huge_pmd(page, vma->vm_page_prot);
610                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
611                 page_add_new_anon_rmap(page, vma, haddr, true);
612                 mem_cgroup_commit_charge(page, memcg, false, true);
613                 lru_cache_add_active_or_unevictable(page, vma);
614                 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
615                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
616                 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
617                 mm_inc_nr_ptes(vma->vm_mm);
618                 spin_unlock(vmf->ptl);
619                 count_vm_event(THP_FAULT_ALLOC);
620                 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
621         }
622
623         return 0;
624 unlock_release:
625         spin_unlock(vmf->ptl);
626 release:
627         if (pgtable)
628                 pte_free(vma->vm_mm, pgtable);
629         mem_cgroup_cancel_charge(page, memcg, true);
630         put_page(page);
631         return ret;
632
633 }
634
635 /*
636  * always: directly stall for all thp allocations
637  * defer: wake kswapd and fail if not immediately available
638  * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
639  *                fail if not immediately available
640  * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
641  *          available
642  * never: never stall for any thp allocation
643  */
644 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
645 {
646         const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
647
648         /* Always do synchronous compaction */
649         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
650                 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
651
652         /* Kick kcompactd and fail quickly */
653         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
654                 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
655
656         /* Synchronous compaction if madvised, otherwise kick kcompactd */
657         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
658                 return GFP_TRANSHUGE_LIGHT |
659                         (vma_madvised ? __GFP_DIRECT_RECLAIM :
660                                         __GFP_KSWAPD_RECLAIM);
661
662         /* Only do synchronous compaction if madvised */
663         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
664                 return GFP_TRANSHUGE_LIGHT |
665                        (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
666
667         return GFP_TRANSHUGE_LIGHT;
668 }
669
670 /* Caller must hold page table lock. */
671 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
672                 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
673                 struct page *zero_page)
674 {
675         pmd_t entry;
676         if (!pmd_none(*pmd))
677                 return false;
678         entry = mk_pmd(zero_page, vma->vm_page_prot);
679         entry = pmd_mkhuge(entry);
680         if (pgtable)
681                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
682         set_pmd_at(mm, haddr, pmd, entry);
683         mm_inc_nr_ptes(mm);
684         return true;
685 }
686
687 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
688 {
689         struct vm_area_struct *vma = vmf->vma;
690         gfp_t gfp;
691         struct page *page;
692         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
693
694         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
695                 return VM_FAULT_FALLBACK;
696         if (unlikely(anon_vma_prepare(vma)))
697                 return VM_FAULT_OOM;
698         if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
699                 return VM_FAULT_OOM;
700         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
701                         !mm_forbids_zeropage(vma->vm_mm) &&
702                         transparent_hugepage_use_zero_page()) {
703                 pgtable_t pgtable;
704                 struct page *zero_page;
705                 bool set;
706                 vm_fault_t ret;
707                 pgtable = pte_alloc_one(vma->vm_mm);
708                 if (unlikely(!pgtable))
709                         return VM_FAULT_OOM;
710                 zero_page = mm_get_huge_zero_page(vma->vm_mm);
711                 if (unlikely(!zero_page)) {
712                         pte_free(vma->vm_mm, pgtable);
713                         count_vm_event(THP_FAULT_FALLBACK);
714                         return VM_FAULT_FALLBACK;
715                 }
716                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
717                 ret = 0;
718                 set = false;
719                 if (pmd_none(*vmf->pmd)) {
720                         ret = check_stable_address_space(vma->vm_mm);
721                         if (ret) {
722                                 spin_unlock(vmf->ptl);
723                         } else if (userfaultfd_missing(vma)) {
724                                 spin_unlock(vmf->ptl);
725                                 ret = handle_userfault(vmf, VM_UFFD_MISSING);
726                                 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
727                         } else {
728                                 set_huge_zero_page(pgtable, vma->vm_mm, vma,
729                                                    haddr, vmf->pmd, zero_page);
730                                 spin_unlock(vmf->ptl);
731                                 set = true;
732                         }
733                 } else
734                         spin_unlock(vmf->ptl);
735                 if (!set)
736                         pte_free(vma->vm_mm, pgtable);
737                 return ret;
738         }
739         gfp = alloc_hugepage_direct_gfpmask(vma);
740         page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
741         if (unlikely(!page)) {
742                 count_vm_event(THP_FAULT_FALLBACK);
743                 return VM_FAULT_FALLBACK;
744         }
745         prep_transhuge_page(page);
746         return __do_huge_pmd_anonymous_page(vmf, page, gfp);
747 }
748
749 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
750                 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
751                 pgtable_t pgtable)
752 {
753         struct mm_struct *mm = vma->vm_mm;
754         pmd_t entry;
755         spinlock_t *ptl;
756
757         ptl = pmd_lock(mm, pmd);
758         entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
759         if (pfn_t_devmap(pfn))
760                 entry = pmd_mkdevmap(entry);
761         if (write) {
762                 entry = pmd_mkyoung(pmd_mkdirty(entry));
763                 entry = maybe_pmd_mkwrite(entry, vma);
764         }
765
766         if (pgtable) {
767                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
768                 mm_inc_nr_ptes(mm);
769         }
770
771         set_pmd_at(mm, addr, pmd, entry);
772         update_mmu_cache_pmd(vma, addr, pmd);
773         spin_unlock(ptl);
774 }
775
776 vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
777                         pmd_t *pmd, pfn_t pfn, bool write)
778 {
779         pgprot_t pgprot = vma->vm_page_prot;
780         pgtable_t pgtable = NULL;
781         /*
782          * If we had pmd_special, we could avoid all these restrictions,
783          * but we need to be consistent with PTEs and architectures that
784          * can't support a 'special' bit.
785          */
786         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
787                         !pfn_t_devmap(pfn));
788         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
789                                                 (VM_PFNMAP|VM_MIXEDMAP));
790         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
791
792         if (addr < vma->vm_start || addr >= vma->vm_end)
793                 return VM_FAULT_SIGBUS;
794
795         if (arch_needs_pgtable_deposit()) {
796                 pgtable = pte_alloc_one(vma->vm_mm);
797                 if (!pgtable)
798                         return VM_FAULT_OOM;
799         }
800
801         track_pfn_insert(vma, &pgprot, pfn);
802
803         insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
804         return VM_FAULT_NOPAGE;
805 }
806 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
807
808 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
809 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
810 {
811         if (likely(vma->vm_flags & VM_WRITE))
812                 pud = pud_mkwrite(pud);
813         return pud;
814 }
815
816 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
817                 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
818 {
819         struct mm_struct *mm = vma->vm_mm;
820         pud_t entry;
821         spinlock_t *ptl;
822
823         ptl = pud_lock(mm, pud);
824         entry = pud_mkhuge(pfn_t_pud(pfn, prot));
825         if (pfn_t_devmap(pfn))
826                 entry = pud_mkdevmap(entry);
827         if (write) {
828                 entry = pud_mkyoung(pud_mkdirty(entry));
829                 entry = maybe_pud_mkwrite(entry, vma);
830         }
831         set_pud_at(mm, addr, pud, entry);
832         update_mmu_cache_pud(vma, addr, pud);
833         spin_unlock(ptl);
834 }
835
836 vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
837                         pud_t *pud, pfn_t pfn, bool write)
838 {
839         pgprot_t pgprot = vma->vm_page_prot;
840         /*
841          * If we had pud_special, we could avoid all these restrictions,
842          * but we need to be consistent with PTEs and architectures that
843          * can't support a 'special' bit.
844          */
845         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
846                         !pfn_t_devmap(pfn));
847         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
848                                                 (VM_PFNMAP|VM_MIXEDMAP));
849         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
850
851         if (addr < vma->vm_start || addr >= vma->vm_end)
852                 return VM_FAULT_SIGBUS;
853
854         track_pfn_insert(vma, &pgprot, pfn);
855
856         insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
857         return VM_FAULT_NOPAGE;
858 }
859 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
860 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
861
862 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
863                 pmd_t *pmd, int flags)
864 {
865         pmd_t _pmd;
866
867         _pmd = pmd_mkyoung(*pmd);
868         if (flags & FOLL_WRITE)
869                 _pmd = pmd_mkdirty(_pmd);
870         if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
871                                 pmd, _pmd, flags & FOLL_WRITE))
872                 update_mmu_cache_pmd(vma, addr, pmd);
873 }
874
875 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
876                 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
877 {
878         unsigned long pfn = pmd_pfn(*pmd);
879         struct mm_struct *mm = vma->vm_mm;
880         struct page *page;
881
882         assert_spin_locked(pmd_lockptr(mm, pmd));
883
884         /*
885          * When we COW a devmap PMD entry, we split it into PTEs, so we should
886          * not be in this function with `flags & FOLL_COW` set.
887          */
888         WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
889
890         if (flags & FOLL_WRITE && !pmd_write(*pmd))
891                 return NULL;
892
893         if (pmd_present(*pmd) && pmd_devmap(*pmd))
894                 /* pass */;
895         else
896                 return NULL;
897
898         if (flags & FOLL_TOUCH)
899                 touch_pmd(vma, addr, pmd, flags);
900
901         /*
902          * device mapped pages can only be returned if the
903          * caller will manage the page reference count.
904          */
905         if (!(flags & FOLL_GET))
906                 return ERR_PTR(-EEXIST);
907
908         pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
909         *pgmap = get_dev_pagemap(pfn, *pgmap);
910         if (!*pgmap)
911                 return ERR_PTR(-EFAULT);
912         page = pfn_to_page(pfn);
913         get_page(page);
914
915         return page;
916 }
917
918 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
919                   pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
920                   struct vm_area_struct *vma)
921 {
922         spinlock_t *dst_ptl, *src_ptl;
923         struct page *src_page;
924         pmd_t pmd;
925         pgtable_t pgtable = NULL;
926         int ret = -ENOMEM;
927
928         /* Skip if can be re-fill on fault */
929         if (!vma_is_anonymous(vma))
930                 return 0;
931
932         pgtable = pte_alloc_one(dst_mm);
933         if (unlikely(!pgtable))
934                 goto out;
935
936         dst_ptl = pmd_lock(dst_mm, dst_pmd);
937         src_ptl = pmd_lockptr(src_mm, src_pmd);
938         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
939
940         ret = -EAGAIN;
941         pmd = *src_pmd;
942
943 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
944         if (unlikely(is_swap_pmd(pmd))) {
945                 swp_entry_t entry = pmd_to_swp_entry(pmd);
946
947                 VM_BUG_ON(!is_pmd_migration_entry(pmd));
948                 if (is_write_migration_entry(entry)) {
949                         make_migration_entry_read(&entry);
950                         pmd = swp_entry_to_pmd(entry);
951                         if (pmd_swp_soft_dirty(*src_pmd))
952                                 pmd = pmd_swp_mksoft_dirty(pmd);
953                         set_pmd_at(src_mm, addr, src_pmd, pmd);
954                 }
955                 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
956                 mm_inc_nr_ptes(dst_mm);
957                 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
958                 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
959                 ret = 0;
960                 goto out_unlock;
961         }
962 #endif
963
964         if (unlikely(!pmd_trans_huge(pmd))) {
965                 pte_free(dst_mm, pgtable);
966                 goto out_unlock;
967         }
968         /*
969          * When page table lock is held, the huge zero pmd should not be
970          * under splitting since we don't split the page itself, only pmd to
971          * a page table.
972          */
973         if (is_huge_zero_pmd(pmd)) {
974                 struct page *zero_page;
975                 /*
976                  * get_huge_zero_page() will never allocate a new page here,
977                  * since we already have a zero page to copy. It just takes a
978                  * reference.
979                  */
980                 zero_page = mm_get_huge_zero_page(dst_mm);
981                 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
982                                 zero_page);
983                 ret = 0;
984                 goto out_unlock;
985         }
986
987         src_page = pmd_page(pmd);
988         VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
989         get_page(src_page);
990         page_dup_rmap(src_page, true);
991         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
992         mm_inc_nr_ptes(dst_mm);
993         pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
994
995         pmdp_set_wrprotect(src_mm, addr, src_pmd);
996         pmd = pmd_mkold(pmd_wrprotect(pmd));
997         set_pmd_at(dst_mm, addr, dst_pmd, pmd);
998
999         ret = 0;
1000 out_unlock:
1001         spin_unlock(src_ptl);
1002         spin_unlock(dst_ptl);
1003 out:
1004         return ret;
1005 }
1006
1007 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1008 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1009                 pud_t *pud, int flags)
1010 {
1011         pud_t _pud;
1012
1013         _pud = pud_mkyoung(*pud);
1014         if (flags & FOLL_WRITE)
1015                 _pud = pud_mkdirty(_pud);
1016         if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1017                                 pud, _pud, flags & FOLL_WRITE))
1018                 update_mmu_cache_pud(vma, addr, pud);
1019 }
1020
1021 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1022                 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1023 {
1024         unsigned long pfn = pud_pfn(*pud);
1025         struct mm_struct *mm = vma->vm_mm;
1026         struct page *page;
1027
1028         assert_spin_locked(pud_lockptr(mm, pud));
1029
1030         if (flags & FOLL_WRITE && !pud_write(*pud))
1031                 return NULL;
1032
1033         if (pud_present(*pud) && pud_devmap(*pud))
1034                 /* pass */;
1035         else
1036                 return NULL;
1037
1038         if (flags & FOLL_TOUCH)
1039                 touch_pud(vma, addr, pud, flags);
1040
1041         /*
1042          * device mapped pages can only be returned if the
1043          * caller will manage the page reference count.
1044          */
1045         if (!(flags & FOLL_GET))
1046                 return ERR_PTR(-EEXIST);
1047
1048         pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1049         *pgmap = get_dev_pagemap(pfn, *pgmap);
1050         if (!*pgmap)
1051                 return ERR_PTR(-EFAULT);
1052         page = pfn_to_page(pfn);
1053         get_page(page);
1054
1055         return page;
1056 }
1057
1058 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1059                   pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1060                   struct vm_area_struct *vma)
1061 {
1062         spinlock_t *dst_ptl, *src_ptl;
1063         pud_t pud;
1064         int ret;
1065
1066         dst_ptl = pud_lock(dst_mm, dst_pud);
1067         src_ptl = pud_lockptr(src_mm, src_pud);
1068         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1069
1070         ret = -EAGAIN;
1071         pud = *src_pud;
1072         if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1073                 goto out_unlock;
1074
1075         /*
1076          * When page table lock is held, the huge zero pud should not be
1077          * under splitting since we don't split the page itself, only pud to
1078          * a page table.
1079          */
1080         if (is_huge_zero_pud(pud)) {
1081                 /* No huge zero pud yet */
1082         }
1083
1084         pudp_set_wrprotect(src_mm, addr, src_pud);
1085         pud = pud_mkold(pud_wrprotect(pud));
1086         set_pud_at(dst_mm, addr, dst_pud, pud);
1087
1088         ret = 0;
1089 out_unlock:
1090         spin_unlock(src_ptl);
1091         spin_unlock(dst_ptl);
1092         return ret;
1093 }
1094
1095 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1096 {
1097         pud_t entry;
1098         unsigned long haddr;
1099         bool write = vmf->flags & FAULT_FLAG_WRITE;
1100
1101         vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1102         if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1103                 goto unlock;
1104
1105         entry = pud_mkyoung(orig_pud);
1106         if (write)
1107                 entry = pud_mkdirty(entry);
1108         haddr = vmf->address & HPAGE_PUD_MASK;
1109         if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1110                 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1111
1112 unlock:
1113         spin_unlock(vmf->ptl);
1114 }
1115 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1116
1117 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1118 {
1119         pmd_t entry;
1120         unsigned long haddr;
1121         bool write = vmf->flags & FAULT_FLAG_WRITE;
1122
1123         vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1124         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1125                 goto unlock;
1126
1127         entry = pmd_mkyoung(orig_pmd);
1128         if (write)
1129                 entry = pmd_mkdirty(entry);
1130         haddr = vmf->address & HPAGE_PMD_MASK;
1131         if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1132                 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1133
1134 unlock:
1135         spin_unlock(vmf->ptl);
1136 }
1137
1138 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1139                         pmd_t orig_pmd, struct page *page)
1140 {
1141         struct vm_area_struct *vma = vmf->vma;
1142         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1143         struct mem_cgroup *memcg;
1144         pgtable_t pgtable;
1145         pmd_t _pmd;
1146         int i;
1147         vm_fault_t ret = 0;
1148         struct page **pages;
1149         struct mmu_notifier_range range;
1150
1151         pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1152                               GFP_KERNEL);
1153         if (unlikely(!pages)) {
1154                 ret |= VM_FAULT_OOM;
1155                 goto out;
1156         }
1157
1158         for (i = 0; i < HPAGE_PMD_NR; i++) {
1159                 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1160                                                vmf->address, page_to_nid(page));
1161                 if (unlikely(!pages[i] ||
1162                              mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1163                                      GFP_KERNEL, &memcg, false))) {
1164                         if (pages[i])
1165                                 put_page(pages[i]);
1166                         while (--i >= 0) {
1167                                 memcg = (void *)page_private(pages[i]);
1168                                 set_page_private(pages[i], 0);
1169                                 mem_cgroup_cancel_charge(pages[i], memcg,
1170                                                 false);
1171                                 put_page(pages[i]);
1172                         }
1173                         kfree(pages);
1174                         ret |= VM_FAULT_OOM;
1175                         goto out;
1176                 }
1177                 set_page_private(pages[i], (unsigned long)memcg);
1178         }
1179
1180         for (i = 0; i < HPAGE_PMD_NR; i++) {
1181                 copy_user_highpage(pages[i], page + i,
1182                                    haddr + PAGE_SIZE * i, vma);
1183                 __SetPageUptodate(pages[i]);
1184                 cond_resched();
1185         }
1186
1187         mmu_notifier_range_init(&range, vma->vm_mm, haddr,
1188                                 haddr + HPAGE_PMD_SIZE);
1189         mmu_notifier_invalidate_range_start(&range);
1190
1191         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1192         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1193                 goto out_free_pages;
1194         VM_BUG_ON_PAGE(!PageHead(page), page);
1195
1196         /*
1197          * Leave pmd empty until pte is filled note we must notify here as
1198          * concurrent CPU thread might write to new page before the call to
1199          * mmu_notifier_invalidate_range_end() happens which can lead to a
1200          * device seeing memory write in different order than CPU.
1201          *
1202          * See Documentation/vm/mmu_notifier.rst
1203          */
1204         pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1205
1206         pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1207         pmd_populate(vma->vm_mm, &_pmd, pgtable);
1208
1209         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1210                 pte_t entry;
1211                 entry = mk_pte(pages[i], vma->vm_page_prot);
1212                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1213                 memcg = (void *)page_private(pages[i]);
1214                 set_page_private(pages[i], 0);
1215                 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1216                 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1217                 lru_cache_add_active_or_unevictable(pages[i], vma);
1218                 vmf->pte = pte_offset_map(&_pmd, haddr);
1219                 VM_BUG_ON(!pte_none(*vmf->pte));
1220                 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1221                 pte_unmap(vmf->pte);
1222         }
1223         kfree(pages);
1224
1225         smp_wmb(); /* make pte visible before pmd */
1226         pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1227         page_remove_rmap(page, true);
1228         spin_unlock(vmf->ptl);
1229
1230         /*
1231          * No need to double call mmu_notifier->invalidate_range() callback as
1232          * the above pmdp_huge_clear_flush_notify() did already call it.
1233          */
1234         mmu_notifier_invalidate_range_only_end(&range);
1235
1236         ret |= VM_FAULT_WRITE;
1237         put_page(page);
1238
1239 out:
1240         return ret;
1241
1242 out_free_pages:
1243         spin_unlock(vmf->ptl);
1244         mmu_notifier_invalidate_range_end(&range);
1245         for (i = 0; i < HPAGE_PMD_NR; i++) {
1246                 memcg = (void *)page_private(pages[i]);
1247                 set_page_private(pages[i], 0);
1248                 mem_cgroup_cancel_charge(pages[i], memcg, false);
1249                 put_page(pages[i]);
1250         }
1251         kfree(pages);
1252         goto out;
1253 }
1254
1255 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1256 {
1257         struct vm_area_struct *vma = vmf->vma;
1258         struct page *page = NULL, *new_page;
1259         struct mem_cgroup *memcg;
1260         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1261         struct mmu_notifier_range range;
1262         gfp_t huge_gfp;                 /* for allocation and charge */
1263         vm_fault_t ret = 0;
1264
1265         vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1266         VM_BUG_ON_VMA(!vma->anon_vma, vma);
1267         if (is_huge_zero_pmd(orig_pmd))
1268                 goto alloc;
1269         spin_lock(vmf->ptl);
1270         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1271                 goto out_unlock;
1272
1273         page = pmd_page(orig_pmd);
1274         VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1275         /*
1276          * We can only reuse the page if nobody else maps the huge page or it's
1277          * part.
1278          */
1279         if (!trylock_page(page)) {
1280                 get_page(page);
1281                 spin_unlock(vmf->ptl);
1282                 lock_page(page);
1283                 spin_lock(vmf->ptl);
1284                 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1285                         unlock_page(page);
1286                         put_page(page);
1287                         goto out_unlock;
1288                 }
1289                 put_page(page);
1290         }
1291         if (reuse_swap_page(page, NULL)) {
1292                 pmd_t entry;
1293                 entry = pmd_mkyoung(orig_pmd);
1294                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1295                 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry,  1))
1296                         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1297                 ret |= VM_FAULT_WRITE;
1298                 unlock_page(page);
1299                 goto out_unlock;
1300         }
1301         unlock_page(page);
1302         get_page(page);
1303         spin_unlock(vmf->ptl);
1304 alloc:
1305         if (__transparent_hugepage_enabled(vma) &&
1306             !transparent_hugepage_debug_cow()) {
1307                 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1308                 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1309         } else
1310                 new_page = NULL;
1311
1312         if (likely(new_page)) {
1313                 prep_transhuge_page(new_page);
1314         } else {
1315                 if (!page) {
1316                         split_huge_pmd(vma, vmf->pmd, vmf->address);
1317                         ret |= VM_FAULT_FALLBACK;
1318                 } else {
1319                         ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1320                         if (ret & VM_FAULT_OOM) {
1321                                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1322                                 ret |= VM_FAULT_FALLBACK;
1323                         }
1324                         put_page(page);
1325                 }
1326                 count_vm_event(THP_FAULT_FALLBACK);
1327                 goto out;
1328         }
1329
1330         if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1331                                         huge_gfp, &memcg, true))) {
1332                 put_page(new_page);
1333                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1334                 if (page)
1335                         put_page(page);
1336                 ret |= VM_FAULT_FALLBACK;
1337                 count_vm_event(THP_FAULT_FALLBACK);
1338                 goto out;
1339         }
1340
1341         count_vm_event(THP_FAULT_ALLOC);
1342         count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1343
1344         if (!page)
1345                 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1346         else
1347                 copy_user_huge_page(new_page, page, vmf->address,
1348                                     vma, HPAGE_PMD_NR);
1349         __SetPageUptodate(new_page);
1350
1351         mmu_notifier_range_init(&range, vma->vm_mm, haddr,
1352                                 haddr + HPAGE_PMD_SIZE);
1353         mmu_notifier_invalidate_range_start(&range);
1354
1355         spin_lock(vmf->ptl);
1356         if (page)
1357                 put_page(page);
1358         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1359                 spin_unlock(vmf->ptl);
1360                 mem_cgroup_cancel_charge(new_page, memcg, true);
1361                 put_page(new_page);
1362                 goto out_mn;
1363         } else {
1364                 pmd_t entry;
1365                 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1366                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1367                 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1368                 page_add_new_anon_rmap(new_page, vma, haddr, true);
1369                 mem_cgroup_commit_charge(new_page, memcg, false, true);
1370                 lru_cache_add_active_or_unevictable(new_page, vma);
1371                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1372                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1373                 if (!page) {
1374                         add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1375                 } else {
1376                         VM_BUG_ON_PAGE(!PageHead(page), page);
1377                         page_remove_rmap(page, true);
1378                         put_page(page);
1379                 }
1380                 ret |= VM_FAULT_WRITE;
1381         }
1382         spin_unlock(vmf->ptl);
1383 out_mn:
1384         /*
1385          * No need to double call mmu_notifier->invalidate_range() callback as
1386          * the above pmdp_huge_clear_flush_notify() did already call it.
1387          */
1388         mmu_notifier_invalidate_range_only_end(&range);
1389 out:
1390         return ret;
1391 out_unlock:
1392         spin_unlock(vmf->ptl);
1393         return ret;
1394 }
1395
1396 /*
1397  * FOLL_FORCE can write to even unwritable pmd's, but only
1398  * after we've gone through a COW cycle and they are dirty.
1399  */
1400 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1401 {
1402         return pmd_write(pmd) ||
1403                ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1404 }
1405
1406 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1407                                    unsigned long addr,
1408                                    pmd_t *pmd,
1409                                    unsigned int flags)
1410 {
1411         struct mm_struct *mm = vma->vm_mm;
1412         struct page *page = NULL;
1413
1414         assert_spin_locked(pmd_lockptr(mm, pmd));
1415
1416         if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1417                 goto out;
1418
1419         /* Avoid dumping huge zero page */
1420         if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1421                 return ERR_PTR(-EFAULT);
1422
1423         /* Full NUMA hinting faults to serialise migration in fault paths */
1424         if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1425                 goto out;
1426
1427         page = pmd_page(*pmd);
1428         VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1429         if (flags & FOLL_TOUCH)
1430                 touch_pmd(vma, addr, pmd, flags);
1431         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1432                 /*
1433                  * We don't mlock() pte-mapped THPs. This way we can avoid
1434                  * leaking mlocked pages into non-VM_LOCKED VMAs.
1435                  *
1436                  * For anon THP:
1437                  *
1438                  * In most cases the pmd is the only mapping of the page as we
1439                  * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1440                  * writable private mappings in populate_vma_page_range().
1441                  *
1442                  * The only scenario when we have the page shared here is if we
1443                  * mlocking read-only mapping shared over fork(). We skip
1444                  * mlocking such pages.
1445                  *
1446                  * For file THP:
1447                  *
1448                  * We can expect PageDoubleMap() to be stable under page lock:
1449                  * for file pages we set it in page_add_file_rmap(), which
1450                  * requires page to be locked.
1451                  */
1452
1453                 if (PageAnon(page) && compound_mapcount(page) != 1)
1454                         goto skip_mlock;
1455                 if (PageDoubleMap(page) || !page->mapping)
1456                         goto skip_mlock;
1457                 if (!trylock_page(page))
1458                         goto skip_mlock;
1459                 lru_add_drain();
1460                 if (page->mapping && !PageDoubleMap(page))
1461                         mlock_vma_page(page);
1462                 unlock_page(page);
1463         }
1464 skip_mlock:
1465         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1466         VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1467         if (flags & FOLL_GET)
1468                 get_page(page);
1469
1470 out:
1471         return page;
1472 }
1473
1474 /* NUMA hinting page fault entry point for trans huge pmds */
1475 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1476 {
1477         struct vm_area_struct *vma = vmf->vma;
1478         struct anon_vma *anon_vma = NULL;
1479         struct page *page;
1480         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1481         int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1482         int target_nid, last_cpupid = -1;
1483         bool page_locked;
1484         bool migrated = false;
1485         bool was_writable;
1486         int flags = 0;
1487
1488         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1489         if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1490                 goto out_unlock;
1491
1492         /*
1493          * If there are potential migrations, wait for completion and retry
1494          * without disrupting NUMA hinting information. Do not relock and
1495          * check_same as the page may no longer be mapped.
1496          */
1497         if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1498                 page = pmd_page(*vmf->pmd);
1499                 if (!get_page_unless_zero(page))
1500                         goto out_unlock;
1501                 spin_unlock(vmf->ptl);
1502                 put_and_wait_on_page_locked(page);
1503                 goto out;
1504         }
1505
1506         page = pmd_page(pmd);
1507         BUG_ON(is_huge_zero_page(page));
1508         page_nid = page_to_nid(page);
1509         last_cpupid = page_cpupid_last(page);
1510         count_vm_numa_event(NUMA_HINT_FAULTS);
1511         if (page_nid == this_nid) {
1512                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1513                 flags |= TNF_FAULT_LOCAL;
1514         }
1515
1516         /* See similar comment in do_numa_page for explanation */
1517         if (!pmd_savedwrite(pmd))
1518                 flags |= TNF_NO_GROUP;
1519
1520         /*
1521          * Acquire the page lock to serialise THP migrations but avoid dropping
1522          * page_table_lock if at all possible
1523          */
1524         page_locked = trylock_page(page);
1525         target_nid = mpol_misplaced(page, vma, haddr);
1526         if (target_nid == NUMA_NO_NODE) {
1527                 /* If the page was locked, there are no parallel migrations */
1528                 if (page_locked)
1529                         goto clear_pmdnuma;
1530         }
1531
1532         /* Migration could have started since the pmd_trans_migrating check */
1533         if (!page_locked) {
1534                 page_nid = NUMA_NO_NODE;
1535                 if (!get_page_unless_zero(page))
1536                         goto out_unlock;
1537                 spin_unlock(vmf->ptl);
1538                 put_and_wait_on_page_locked(page);
1539                 goto out;
1540         }
1541
1542         /*
1543          * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1544          * to serialises splits
1545          */
1546         get_page(page);
1547         spin_unlock(vmf->ptl);
1548         anon_vma = page_lock_anon_vma_read(page);
1549
1550         /* Confirm the PMD did not change while page_table_lock was released */
1551         spin_lock(vmf->ptl);
1552         if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1553                 unlock_page(page);
1554                 put_page(page);
1555                 page_nid = NUMA_NO_NODE;
1556                 goto out_unlock;
1557         }
1558
1559         /* Bail if we fail to protect against THP splits for any reason */
1560         if (unlikely(!anon_vma)) {
1561                 put_page(page);
1562                 page_nid = NUMA_NO_NODE;
1563                 goto clear_pmdnuma;
1564         }
1565
1566         /*
1567          * Since we took the NUMA fault, we must have observed the !accessible
1568          * bit. Make sure all other CPUs agree with that, to avoid them
1569          * modifying the page we're about to migrate.
1570          *
1571          * Must be done under PTL such that we'll observe the relevant
1572          * inc_tlb_flush_pending().
1573          *
1574          * We are not sure a pending tlb flush here is for a huge page
1575          * mapping or not. Hence use the tlb range variant
1576          */
1577         if (mm_tlb_flush_pending(vma->vm_mm)) {
1578                 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1579                 /*
1580                  * change_huge_pmd() released the pmd lock before
1581                  * invalidating the secondary MMUs sharing the primary
1582                  * MMU pagetables (with ->invalidate_range()). The
1583                  * mmu_notifier_invalidate_range_end() (which
1584                  * internally calls ->invalidate_range()) in
1585                  * change_pmd_range() will run after us, so we can't
1586                  * rely on it here and we need an explicit invalidate.
1587                  */
1588                 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1589                                               haddr + HPAGE_PMD_SIZE);
1590         }
1591
1592         /*
1593          * Migrate the THP to the requested node, returns with page unlocked
1594          * and access rights restored.
1595          */
1596         spin_unlock(vmf->ptl);
1597
1598         migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1599                                 vmf->pmd, pmd, vmf->address, page, target_nid);
1600         if (migrated) {
1601                 flags |= TNF_MIGRATED;
1602                 page_nid = target_nid;
1603         } else
1604                 flags |= TNF_MIGRATE_FAIL;
1605
1606         goto out;
1607 clear_pmdnuma:
1608         BUG_ON(!PageLocked(page));
1609         was_writable = pmd_savedwrite(pmd);
1610         pmd = pmd_modify(pmd, vma->vm_page_prot);
1611         pmd = pmd_mkyoung(pmd);
1612         if (was_writable)
1613                 pmd = pmd_mkwrite(pmd);
1614         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1615         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1616         unlock_page(page);
1617 out_unlock:
1618         spin_unlock(vmf->ptl);
1619
1620 out:
1621         if (anon_vma)
1622                 page_unlock_anon_vma_read(anon_vma);
1623
1624         if (page_nid != NUMA_NO_NODE)
1625                 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1626                                 flags);
1627
1628         return 0;
1629 }
1630
1631 /*
1632  * Return true if we do MADV_FREE successfully on entire pmd page.
1633  * Otherwise, return false.
1634  */
1635 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1636                 pmd_t *pmd, unsigned long addr, unsigned long next)
1637 {
1638         spinlock_t *ptl;
1639         pmd_t orig_pmd;
1640         struct page *page;
1641         struct mm_struct *mm = tlb->mm;
1642         bool ret = false;
1643
1644         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1645
1646         ptl = pmd_trans_huge_lock(pmd, vma);
1647         if (!ptl)
1648                 goto out_unlocked;
1649
1650         orig_pmd = *pmd;
1651         if (is_huge_zero_pmd(orig_pmd))
1652                 goto out;
1653
1654         if (unlikely(!pmd_present(orig_pmd))) {
1655                 VM_BUG_ON(thp_migration_supported() &&
1656                                   !is_pmd_migration_entry(orig_pmd));
1657                 goto out;
1658         }
1659
1660         page = pmd_page(orig_pmd);
1661         /*
1662          * If other processes are mapping this page, we couldn't discard
1663          * the page unless they all do MADV_FREE so let's skip the page.
1664          */
1665         if (page_mapcount(page) != 1)
1666                 goto out;
1667
1668         if (!trylock_page(page))
1669                 goto out;
1670
1671         /*
1672          * If user want to discard part-pages of THP, split it so MADV_FREE
1673          * will deactivate only them.
1674          */
1675         if (next - addr != HPAGE_PMD_SIZE) {
1676                 get_page(page);
1677                 spin_unlock(ptl);
1678                 split_huge_page(page);
1679                 unlock_page(page);
1680                 put_page(page);
1681                 goto out_unlocked;
1682         }
1683
1684         if (PageDirty(page))
1685                 ClearPageDirty(page);
1686         unlock_page(page);
1687
1688         if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1689                 pmdp_invalidate(vma, addr, pmd);
1690                 orig_pmd = pmd_mkold(orig_pmd);
1691                 orig_pmd = pmd_mkclean(orig_pmd);
1692
1693                 set_pmd_at(mm, addr, pmd, orig_pmd);
1694                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1695         }
1696
1697         mark_page_lazyfree(page);
1698         ret = true;
1699 out:
1700         spin_unlock(ptl);
1701 out_unlocked:
1702         return ret;
1703 }
1704
1705 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1706 {
1707         pgtable_t pgtable;
1708
1709         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1710         pte_free(mm, pgtable);
1711         mm_dec_nr_ptes(mm);
1712 }
1713
1714 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1715                  pmd_t *pmd, unsigned long addr)
1716 {
1717         pmd_t orig_pmd;
1718         spinlock_t *ptl;
1719
1720         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1721
1722         ptl = __pmd_trans_huge_lock(pmd, vma);
1723         if (!ptl)
1724                 return 0;
1725         /*
1726          * For architectures like ppc64 we look at deposited pgtable
1727          * when calling pmdp_huge_get_and_clear. So do the
1728          * pgtable_trans_huge_withdraw after finishing pmdp related
1729          * operations.
1730          */
1731         orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1732                         tlb->fullmm);
1733         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1734         if (vma_is_dax(vma)) {
1735                 if (arch_needs_pgtable_deposit())
1736                         zap_deposited_table(tlb->mm, pmd);
1737                 spin_unlock(ptl);
1738                 if (is_huge_zero_pmd(orig_pmd))
1739                         tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1740         } else if (is_huge_zero_pmd(orig_pmd)) {
1741                 zap_deposited_table(tlb->mm, pmd);
1742                 spin_unlock(ptl);
1743                 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1744         } else {
1745                 struct page *page = NULL;
1746                 int flush_needed = 1;
1747
1748                 if (pmd_present(orig_pmd)) {
1749                         page = pmd_page(orig_pmd);
1750                         page_remove_rmap(page, true);
1751                         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1752                         VM_BUG_ON_PAGE(!PageHead(page), page);
1753                 } else if (thp_migration_supported()) {
1754                         swp_entry_t entry;
1755
1756                         VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1757                         entry = pmd_to_swp_entry(orig_pmd);
1758                         page = pfn_to_page(swp_offset(entry));
1759                         flush_needed = 0;
1760                 } else
1761                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1762
1763                 if (PageAnon(page)) {
1764                         zap_deposited_table(tlb->mm, pmd);
1765                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1766                 } else {
1767                         if (arch_needs_pgtable_deposit())
1768                                 zap_deposited_table(tlb->mm, pmd);
1769                         add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1770                 }
1771
1772                 spin_unlock(ptl);
1773                 if (flush_needed)
1774                         tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1775         }
1776         return 1;
1777 }
1778
1779 #ifndef pmd_move_must_withdraw
1780 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1781                                          spinlock_t *old_pmd_ptl,
1782                                          struct vm_area_struct *vma)
1783 {
1784         /*
1785          * With split pmd lock we also need to move preallocated
1786          * PTE page table if new_pmd is on different PMD page table.
1787          *
1788          * We also don't deposit and withdraw tables for file pages.
1789          */
1790         return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1791 }
1792 #endif
1793
1794 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1795 {
1796 #ifdef CONFIG_MEM_SOFT_DIRTY
1797         if (unlikely(is_pmd_migration_entry(pmd)))
1798                 pmd = pmd_swp_mksoft_dirty(pmd);
1799         else if (pmd_present(pmd))
1800                 pmd = pmd_mksoft_dirty(pmd);
1801 #endif
1802         return pmd;
1803 }
1804
1805 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1806                   unsigned long new_addr, unsigned long old_end,
1807                   pmd_t *old_pmd, pmd_t *new_pmd)
1808 {
1809         spinlock_t *old_ptl, *new_ptl;
1810         pmd_t pmd;
1811         struct mm_struct *mm = vma->vm_mm;
1812         bool force_flush = false;
1813
1814         if ((old_addr & ~HPAGE_PMD_MASK) ||
1815             (new_addr & ~HPAGE_PMD_MASK) ||
1816             old_end - old_addr < HPAGE_PMD_SIZE)
1817                 return false;
1818
1819         /*
1820          * The destination pmd shouldn't be established, free_pgtables()
1821          * should have release it.
1822          */
1823         if (WARN_ON(!pmd_none(*new_pmd))) {
1824                 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1825                 return false;
1826         }
1827
1828         /*
1829          * We don't have to worry about the ordering of src and dst
1830          * ptlocks because exclusive mmap_sem prevents deadlock.
1831          */
1832         old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1833         if (old_ptl) {
1834                 new_ptl = pmd_lockptr(mm, new_pmd);
1835                 if (new_ptl != old_ptl)
1836                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1837                 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1838                 if (pmd_present(pmd))
1839                         force_flush = true;
1840                 VM_BUG_ON(!pmd_none(*new_pmd));
1841
1842                 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1843                         pgtable_t pgtable;
1844                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1845                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1846                 }
1847                 pmd = move_soft_dirty_pmd(pmd);
1848                 set_pmd_at(mm, new_addr, new_pmd, pmd);
1849                 if (force_flush)
1850                         flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1851                 if (new_ptl != old_ptl)
1852                         spin_unlock(new_ptl);
1853                 spin_unlock(old_ptl);
1854                 return true;
1855         }
1856         return false;
1857 }
1858
1859 /*
1860  * Returns
1861  *  - 0 if PMD could not be locked
1862  *  - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1863  *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
1864  */
1865 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1866                 unsigned long addr, pgprot_t newprot, int prot_numa)
1867 {
1868         struct mm_struct *mm = vma->vm_mm;
1869         spinlock_t *ptl;
1870         pmd_t entry;
1871         bool preserve_write;
1872         int ret;
1873
1874         ptl = __pmd_trans_huge_lock(pmd, vma);
1875         if (!ptl)
1876                 return 0;
1877
1878         preserve_write = prot_numa && pmd_write(*pmd);
1879         ret = 1;
1880
1881 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1882         if (is_swap_pmd(*pmd)) {
1883                 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1884
1885                 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1886                 if (is_write_migration_entry(entry)) {
1887                         pmd_t newpmd;
1888                         /*
1889                          * A protection check is difficult so
1890                          * just be safe and disable write
1891                          */
1892                         make_migration_entry_read(&entry);
1893                         newpmd = swp_entry_to_pmd(entry);
1894                         if (pmd_swp_soft_dirty(*pmd))
1895                                 newpmd = pmd_swp_mksoft_dirty(newpmd);
1896                         set_pmd_at(mm, addr, pmd, newpmd);
1897                 }
1898                 goto unlock;
1899         }
1900 #endif
1901
1902         /*
1903          * Avoid trapping faults against the zero page. The read-only
1904          * data is likely to be read-cached on the local CPU and
1905          * local/remote hits to the zero page are not interesting.
1906          */
1907         if (prot_numa && is_huge_zero_pmd(*pmd))
1908                 goto unlock;
1909
1910         if (prot_numa && pmd_protnone(*pmd))
1911                 goto unlock;
1912
1913         /*
1914          * In case prot_numa, we are under down_read(mmap_sem). It's critical
1915          * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1916          * which is also under down_read(mmap_sem):
1917          *
1918          *      CPU0:                           CPU1:
1919          *                              change_huge_pmd(prot_numa=1)
1920          *                               pmdp_huge_get_and_clear_notify()
1921          * madvise_dontneed()
1922          *  zap_pmd_range()
1923          *   pmd_trans_huge(*pmd) == 0 (without ptl)
1924          *   // skip the pmd
1925          *                               set_pmd_at();
1926          *                               // pmd is re-established
1927          *
1928          * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1929          * which may break userspace.
1930          *
1931          * pmdp_invalidate() is required to make sure we don't miss
1932          * dirty/young flags set by hardware.
1933          */
1934         entry = pmdp_invalidate(vma, addr, pmd);
1935
1936         entry = pmd_modify(entry, newprot);
1937         if (preserve_write)
1938                 entry = pmd_mk_savedwrite(entry);
1939         ret = HPAGE_PMD_NR;
1940         set_pmd_at(mm, addr, pmd, entry);
1941         BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1942 unlock:
1943         spin_unlock(ptl);
1944         return ret;
1945 }
1946
1947 /*
1948  * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1949  *
1950  * Note that if it returns page table lock pointer, this routine returns without
1951  * unlocking page table lock. So callers must unlock it.
1952  */
1953 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1954 {
1955         spinlock_t *ptl;
1956         ptl = pmd_lock(vma->vm_mm, pmd);
1957         if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1958                         pmd_devmap(*pmd)))
1959                 return ptl;
1960         spin_unlock(ptl);
1961         return NULL;
1962 }
1963
1964 /*
1965  * Returns true if a given pud maps a thp, false otherwise.
1966  *
1967  * Note that if it returns true, this routine returns without unlocking page
1968  * table lock. So callers must unlock it.
1969  */
1970 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1971 {
1972         spinlock_t *ptl;
1973
1974         ptl = pud_lock(vma->vm_mm, pud);
1975         if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1976                 return ptl;
1977         spin_unlock(ptl);
1978         return NULL;
1979 }
1980
1981 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1982 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1983                  pud_t *pud, unsigned long addr)
1984 {
1985         pud_t orig_pud;
1986         spinlock_t *ptl;
1987
1988         ptl = __pud_trans_huge_lock(pud, vma);
1989         if (!ptl)
1990                 return 0;
1991         /*
1992          * For architectures like ppc64 we look at deposited pgtable
1993          * when calling pudp_huge_get_and_clear. So do the
1994          * pgtable_trans_huge_withdraw after finishing pudp related
1995          * operations.
1996          */
1997         orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1998                         tlb->fullmm);
1999         tlb_remove_pud_tlb_entry(tlb, pud, addr);
2000         if (vma_is_dax(vma)) {
2001                 spin_unlock(ptl);
2002                 /* No zero page support yet */
2003         } else {
2004                 /* No support for anonymous PUD pages yet */
2005                 BUG();
2006         }
2007         return 1;
2008 }
2009
2010 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2011                 unsigned long haddr)
2012 {
2013         VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2014         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2015         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2016         VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2017
2018         count_vm_event(THP_SPLIT_PUD);
2019
2020         pudp_huge_clear_flush_notify(vma, haddr, pud);
2021 }
2022
2023 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2024                 unsigned long address)
2025 {
2026         spinlock_t *ptl;
2027         struct mmu_notifier_range range;
2028
2029         mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PUD_MASK,
2030                                 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2031         mmu_notifier_invalidate_range_start(&range);
2032         ptl = pud_lock(vma->vm_mm, pud);
2033         if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2034                 goto out;
2035         __split_huge_pud_locked(vma, pud, range.start);
2036
2037 out:
2038         spin_unlock(ptl);
2039         /*
2040          * No need to double call mmu_notifier->invalidate_range() callback as
2041          * the above pudp_huge_clear_flush_notify() did already call it.
2042          */
2043         mmu_notifier_invalidate_range_only_end(&range);
2044 }
2045 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2046
2047 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2048                 unsigned long haddr, pmd_t *pmd)
2049 {
2050         struct mm_struct *mm = vma->vm_mm;
2051         pgtable_t pgtable;
2052         pmd_t _pmd;
2053         int i;
2054
2055         /*
2056          * Leave pmd empty until pte is filled note that it is fine to delay
2057          * notification until mmu_notifier_invalidate_range_end() as we are
2058          * replacing a zero pmd write protected page with a zero pte write
2059          * protected page.
2060          *
2061          * See Documentation/vm/mmu_notifier.rst
2062          */
2063         pmdp_huge_clear_flush(vma, haddr, pmd);
2064
2065         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2066         pmd_populate(mm, &_pmd, pgtable);
2067
2068         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2069                 pte_t *pte, entry;
2070                 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2071                 entry = pte_mkspecial(entry);
2072                 pte = pte_offset_map(&_pmd, haddr);
2073                 VM_BUG_ON(!pte_none(*pte));
2074                 set_pte_at(mm, haddr, pte, entry);
2075                 pte_unmap(pte);
2076         }
2077         smp_wmb(); /* make pte visible before pmd */
2078         pmd_populate(mm, pmd, pgtable);
2079 }
2080
2081 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2082                 unsigned long haddr, bool freeze)
2083 {
2084         struct mm_struct *mm = vma->vm_mm;
2085         struct page *page;
2086         pgtable_t pgtable;
2087         pmd_t old_pmd, _pmd;
2088         bool young, write, soft_dirty, pmd_migration = false;
2089         unsigned long addr;
2090         int i;
2091
2092         VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2093         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2094         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2095         VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2096                                 && !pmd_devmap(*pmd));
2097
2098         count_vm_event(THP_SPLIT_PMD);
2099
2100         if (!vma_is_anonymous(vma)) {
2101                 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2102                 /*
2103                  * We are going to unmap this huge page. So
2104                  * just go ahead and zap it
2105                  */
2106                 if (arch_needs_pgtable_deposit())
2107                         zap_deposited_table(mm, pmd);
2108                 if (vma_is_dax(vma))
2109                         return;
2110                 page = pmd_page(_pmd);
2111                 if (!PageDirty(page) && pmd_dirty(_pmd))
2112                         set_page_dirty(page);
2113                 if (!PageReferenced(page) && pmd_young(_pmd))
2114                         SetPageReferenced(page);
2115                 page_remove_rmap(page, true);
2116                 put_page(page);
2117                 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2118                 return;
2119         } else if (is_huge_zero_pmd(*pmd)) {
2120                 /*
2121                  * FIXME: Do we want to invalidate secondary mmu by calling
2122                  * mmu_notifier_invalidate_range() see comments below inside
2123                  * __split_huge_pmd() ?
2124                  *
2125                  * We are going from a zero huge page write protected to zero
2126                  * small page also write protected so it does not seems useful
2127                  * to invalidate secondary mmu at this time.
2128                  */
2129                 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2130         }
2131
2132         /*
2133          * Up to this point the pmd is present and huge and userland has the
2134          * whole access to the hugepage during the split (which happens in
2135          * place). If we overwrite the pmd with the not-huge version pointing
2136          * to the pte here (which of course we could if all CPUs were bug
2137          * free), userland could trigger a small page size TLB miss on the
2138          * small sized TLB while the hugepage TLB entry is still established in
2139          * the huge TLB. Some CPU doesn't like that.
2140          * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2141          * 383 on page 93. Intel should be safe but is also warns that it's
2142          * only safe if the permission and cache attributes of the two entries
2143          * loaded in the two TLB is identical (which should be the case here).
2144          * But it is generally safer to never allow small and huge TLB entries
2145          * for the same virtual address to be loaded simultaneously. So instead
2146          * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2147          * current pmd notpresent (atomically because here the pmd_trans_huge
2148          * must remain set at all times on the pmd until the split is complete
2149          * for this pmd), then we flush the SMP TLB and finally we write the
2150          * non-huge version of the pmd entry with pmd_populate.
2151          */
2152         old_pmd = pmdp_invalidate(vma, haddr, pmd);
2153
2154         pmd_migration = is_pmd_migration_entry(old_pmd);
2155         if (unlikely(pmd_migration)) {
2156                 swp_entry_t entry;
2157
2158                 entry = pmd_to_swp_entry(old_pmd);
2159                 page = pfn_to_page(swp_offset(entry));
2160                 write = is_write_migration_entry(entry);
2161                 young = false;
2162                 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2163         } else {
2164                 page = pmd_page(old_pmd);
2165                 if (pmd_dirty(old_pmd))
2166                         SetPageDirty(page);
2167                 write = pmd_write(old_pmd);
2168                 young = pmd_young(old_pmd);
2169                 soft_dirty = pmd_soft_dirty(old_pmd);
2170         }
2171         VM_BUG_ON_PAGE(!page_count(page), page);
2172         page_ref_add(page, HPAGE_PMD_NR - 1);
2173
2174         /*
2175          * Withdraw the table only after we mark the pmd entry invalid.
2176          * This's critical for some architectures (Power).
2177          */
2178         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2179         pmd_populate(mm, &_pmd, pgtable);
2180
2181         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2182                 pte_t entry, *pte;
2183                 /*
2184                  * Note that NUMA hinting access restrictions are not
2185                  * transferred to avoid any possibility of altering
2186                  * permissions across VMAs.
2187                  */
2188                 if (freeze || pmd_migration) {
2189                         swp_entry_t swp_entry;
2190                         swp_entry = make_migration_entry(page + i, write);
2191                         entry = swp_entry_to_pte(swp_entry);
2192                         if (soft_dirty)
2193                                 entry = pte_swp_mksoft_dirty(entry);
2194                 } else {
2195                         entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2196                         entry = maybe_mkwrite(entry, vma);
2197                         if (!write)
2198                                 entry = pte_wrprotect(entry);
2199                         if (!young)
2200                                 entry = pte_mkold(entry);
2201                         if (soft_dirty)
2202                                 entry = pte_mksoft_dirty(entry);
2203                 }
2204                 pte = pte_offset_map(&_pmd, addr);
2205                 BUG_ON(!pte_none(*pte));
2206                 set_pte_at(mm, addr, pte, entry);
2207                 atomic_inc(&page[i]._mapcount);
2208                 pte_unmap(pte);
2209         }
2210
2211         /*
2212          * Set PG_double_map before dropping compound_mapcount to avoid
2213          * false-negative page_mapped().
2214          */
2215         if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2216                 for (i = 0; i < HPAGE_PMD_NR; i++)
2217                         atomic_inc(&page[i]._mapcount);
2218         }
2219
2220         if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2221                 /* Last compound_mapcount is gone. */
2222                 __dec_node_page_state(page, NR_ANON_THPS);
2223                 if (TestClearPageDoubleMap(page)) {
2224                         /* No need in mapcount reference anymore */
2225                         for (i = 0; i < HPAGE_PMD_NR; i++)
2226                                 atomic_dec(&page[i]._mapcount);
2227                 }
2228         }
2229
2230         smp_wmb(); /* make pte visible before pmd */
2231         pmd_populate(mm, pmd, pgtable);
2232
2233         if (freeze) {
2234                 for (i = 0; i < HPAGE_PMD_NR; i++) {
2235                         page_remove_rmap(page + i, false);
2236                         put_page(page + i);
2237                 }
2238         }
2239 }
2240
2241 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2242                 unsigned long address, bool freeze, struct page *page)
2243 {
2244         spinlock_t *ptl;
2245         struct mmu_notifier_range range;
2246
2247         mmu_notifier_range_init(&range, vma->vm_mm, address & HPAGE_PMD_MASK,
2248                                 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2249         mmu_notifier_invalidate_range_start(&range);
2250         ptl = pmd_lock(vma->vm_mm, pmd);
2251
2252         /*
2253          * If caller asks to setup a migration entries, we need a page to check
2254          * pmd against. Otherwise we can end up replacing wrong page.
2255          */
2256         VM_BUG_ON(freeze && !page);
2257         if (page && page != pmd_page(*pmd))
2258                 goto out;
2259
2260         if (pmd_trans_huge(*pmd)) {
2261                 page = pmd_page(*pmd);
2262                 if (PageMlocked(page))
2263                         clear_page_mlock(page);
2264         } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2265                 goto out;
2266         __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2267 out:
2268         spin_unlock(ptl);
2269         /*
2270          * No need to double call mmu_notifier->invalidate_range() callback.
2271          * They are 3 cases to consider inside __split_huge_pmd_locked():
2272          *  1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2273          *  2) __split_huge_zero_page_pmd() read only zero page and any write
2274          *    fault will trigger a flush_notify before pointing to a new page
2275          *    (it is fine if the secondary mmu keeps pointing to the old zero
2276          *    page in the meantime)
2277          *  3) Split a huge pmd into pte pointing to the same page. No need
2278          *     to invalidate secondary tlb entry they are all still valid.
2279          *     any further changes to individual pte will notify. So no need
2280          *     to call mmu_notifier->invalidate_range()
2281          */
2282         mmu_notifier_invalidate_range_only_end(&range);
2283 }
2284
2285 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2286                 bool freeze, struct page *page)
2287 {
2288         pgd_t *pgd;
2289         p4d_t *p4d;
2290         pud_t *pud;
2291         pmd_t *pmd;
2292
2293         pgd = pgd_offset(vma->vm_mm, address);
2294         if (!pgd_present(*pgd))
2295                 return;
2296
2297         p4d = p4d_offset(pgd, address);
2298         if (!p4d_present(*p4d))
2299                 return;
2300
2301         pud = pud_offset(p4d, address);
2302         if (!pud_present(*pud))
2303                 return;
2304
2305         pmd = pmd_offset(pud, address);
2306
2307         __split_huge_pmd(vma, pmd, address, freeze, page);
2308 }
2309
2310 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2311                              unsigned long start,
2312                              unsigned long end,
2313                              long adjust_next)
2314 {
2315         /*
2316          * If the new start address isn't hpage aligned and it could
2317          * previously contain an hugepage: check if we need to split
2318          * an huge pmd.
2319          */
2320         if (start & ~HPAGE_PMD_MASK &&
2321             (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2322             (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2323                 split_huge_pmd_address(vma, start, false, NULL);
2324
2325         /*
2326          * If the new end address isn't hpage aligned and it could
2327          * previously contain an hugepage: check if we need to split
2328          * an huge pmd.
2329          */
2330         if (end & ~HPAGE_PMD_MASK &&
2331             (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2332             (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2333                 split_huge_pmd_address(vma, end, false, NULL);
2334
2335         /*
2336          * If we're also updating the vma->vm_next->vm_start, if the new
2337          * vm_next->vm_start isn't page aligned and it could previously
2338          * contain an hugepage: check if we need to split an huge pmd.
2339          */
2340         if (adjust_next > 0) {
2341                 struct vm_area_struct *next = vma->vm_next;
2342                 unsigned long nstart = next->vm_start;
2343                 nstart += adjust_next << PAGE_SHIFT;
2344                 if (nstart & ~HPAGE_PMD_MASK &&
2345                     (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2346                     (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2347                         split_huge_pmd_address(next, nstart, false, NULL);
2348         }
2349 }
2350
2351 static void unmap_page(struct page *page)
2352 {
2353         enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2354                 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2355         bool unmap_success;
2356
2357         VM_BUG_ON_PAGE(!PageHead(page), page);
2358
2359         if (PageAnon(page))
2360                 ttu_flags |= TTU_SPLIT_FREEZE;
2361
2362         unmap_success = try_to_unmap(page, ttu_flags);
2363         VM_BUG_ON_PAGE(!unmap_success, page);
2364 }
2365
2366 static void remap_page(struct page *page)
2367 {
2368         int i;
2369         if (PageTransHuge(page)) {
2370                 remove_migration_ptes(page, page, true);
2371         } else {
2372                 for (i = 0; i < HPAGE_PMD_NR; i++)
2373                         remove_migration_ptes(page + i, page + i, true);
2374         }
2375 }
2376
2377 static void __split_huge_page_tail(struct page *head, int tail,
2378                 struct lruvec *lruvec, struct list_head *list)
2379 {
2380         struct page *page_tail = head + tail;
2381
2382         VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2383
2384         /*
2385          * Clone page flags before unfreezing refcount.
2386          *
2387          * After successful get_page_unless_zero() might follow flags change,
2388          * for exmaple lock_page() which set PG_waiters.
2389          */
2390         page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2391         page_tail->flags |= (head->flags &
2392                         ((1L << PG_referenced) |
2393                          (1L << PG_swapbacked) |
2394                          (1L << PG_swapcache) |
2395                          (1L << PG_mlocked) |
2396                          (1L << PG_uptodate) |
2397                          (1L << PG_active) |
2398                          (1L << PG_workingset) |
2399                          (1L << PG_locked) |
2400                          (1L << PG_unevictable) |
2401                          (1L << PG_dirty)));
2402
2403         /* ->mapping in first tail page is compound_mapcount */
2404         VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2405                         page_tail);
2406         page_tail->mapping = head->mapping;
2407         page_tail->index = head->index + tail;
2408
2409         /* Page flags must be visible before we make the page non-compound. */
2410         smp_wmb();
2411
2412         /*
2413          * Clear PageTail before unfreezing page refcount.
2414          *
2415          * After successful get_page_unless_zero() might follow put_page()
2416          * which needs correct compound_head().
2417          */
2418         clear_compound_head(page_tail);
2419
2420         /* Finally unfreeze refcount. Additional reference from page cache. */
2421         page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2422                                           PageSwapCache(head)));
2423
2424         if (page_is_young(head))
2425                 set_page_young(page_tail);
2426         if (page_is_idle(head))
2427                 set_page_idle(page_tail);
2428
2429         page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2430
2431         /*
2432          * always add to the tail because some iterators expect new
2433          * pages to show after the currently processed elements - e.g.
2434          * migrate_pages
2435          */
2436         lru_add_page_tail(head, page_tail, lruvec, list);
2437 }
2438
2439 static void __split_huge_page(struct page *page, struct list_head *list,
2440                 pgoff_t end, unsigned long flags)
2441 {
2442         struct page *head = compound_head(page);
2443         struct zone *zone = page_zone(head);
2444         struct lruvec *lruvec;
2445         int i;
2446
2447         lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2448
2449         /* complete memcg works before add pages to LRU */
2450         mem_cgroup_split_huge_fixup(head);
2451
2452         for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2453                 __split_huge_page_tail(head, i, lruvec, list);
2454                 /* Some pages can be beyond i_size: drop them from page cache */
2455                 if (head[i].index >= end) {
2456                         ClearPageDirty(head + i);
2457                         __delete_from_page_cache(head + i, NULL);
2458                         if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2459                                 shmem_uncharge(head->mapping->host, 1);
2460                         put_page(head + i);
2461                 }
2462         }
2463
2464         ClearPageCompound(head);
2465         /* See comment in __split_huge_page_tail() */
2466         if (PageAnon(head)) {
2467                 /* Additional pin to swap cache */
2468                 if (PageSwapCache(head))
2469                         page_ref_add(head, 2);
2470                 else
2471                         page_ref_inc(head);
2472         } else {
2473                 /* Additional pin to page cache */
2474                 page_ref_add(head, 2);
2475                 xa_unlock(&head->mapping->i_pages);
2476         }
2477
2478         spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2479
2480         remap_page(head);
2481
2482         for (i = 0; i < HPAGE_PMD_NR; i++) {
2483                 struct page *subpage = head + i;
2484                 if (subpage == page)
2485                         continue;
2486                 unlock_page(subpage);
2487
2488                 /*
2489                  * Subpages may be freed if there wasn't any mapping
2490                  * like if add_to_swap() is running on a lru page that
2491                  * had its mapping zapped. And freeing these pages
2492                  * requires taking the lru_lock so we do the put_page
2493                  * of the tail pages after the split is complete.
2494                  */
2495                 put_page(subpage);
2496         }
2497 }
2498
2499 int total_mapcount(struct page *page)
2500 {
2501         int i, compound, ret;
2502
2503         VM_BUG_ON_PAGE(PageTail(page), page);
2504
2505         if (likely(!PageCompound(page)))
2506                 return atomic_read(&page->_mapcount) + 1;
2507
2508         compound = compound_mapcount(page);
2509         if (PageHuge(page))
2510                 return compound;
2511         ret = compound;
2512         for (i = 0; i < HPAGE_PMD_NR; i++)
2513                 ret += atomic_read(&page[i]._mapcount) + 1;
2514         /* File pages has compound_mapcount included in _mapcount */
2515         if (!PageAnon(page))
2516                 return ret - compound * HPAGE_PMD_NR;
2517         if (PageDoubleMap(page))
2518                 ret -= HPAGE_PMD_NR;
2519         return ret;
2520 }
2521
2522 /*
2523  * This calculates accurately how many mappings a transparent hugepage
2524  * has (unlike page_mapcount() which isn't fully accurate). This full
2525  * accuracy is primarily needed to know if copy-on-write faults can
2526  * reuse the page and change the mapping to read-write instead of
2527  * copying them. At the same time this returns the total_mapcount too.
2528  *
2529  * The function returns the highest mapcount any one of the subpages
2530  * has. If the return value is one, even if different processes are
2531  * mapping different subpages of the transparent hugepage, they can
2532  * all reuse it, because each process is reusing a different subpage.
2533  *
2534  * The total_mapcount is instead counting all virtual mappings of the
2535  * subpages. If the total_mapcount is equal to "one", it tells the
2536  * caller all mappings belong to the same "mm" and in turn the
2537  * anon_vma of the transparent hugepage can become the vma->anon_vma
2538  * local one as no other process may be mapping any of the subpages.
2539  *
2540  * It would be more accurate to replace page_mapcount() with
2541  * page_trans_huge_mapcount(), however we only use
2542  * page_trans_huge_mapcount() in the copy-on-write faults where we
2543  * need full accuracy to avoid breaking page pinning, because
2544  * page_trans_huge_mapcount() is slower than page_mapcount().
2545  */
2546 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2547 {
2548         int i, ret, _total_mapcount, mapcount;
2549
2550         /* hugetlbfs shouldn't call it */
2551         VM_BUG_ON_PAGE(PageHuge(page), page);
2552
2553         if (likely(!PageTransCompound(page))) {
2554                 mapcount = atomic_read(&page->_mapcount) + 1;
2555                 if (total_mapcount)
2556                         *total_mapcount = mapcount;
2557                 return mapcount;
2558         }
2559
2560         page = compound_head(page);
2561
2562         _total_mapcount = ret = 0;
2563         for (i = 0; i < HPAGE_PMD_NR; i++) {
2564                 mapcount = atomic_read(&page[i]._mapcount) + 1;
2565                 ret = max(ret, mapcount);
2566                 _total_mapcount += mapcount;
2567         }
2568         if (PageDoubleMap(page)) {
2569                 ret -= 1;
2570                 _total_mapcount -= HPAGE_PMD_NR;
2571         }
2572         mapcount = compound_mapcount(page);
2573         ret += mapcount;
2574         _total_mapcount += mapcount;
2575         if (total_mapcount)
2576                 *total_mapcount = _total_mapcount;
2577         return ret;
2578 }
2579
2580 /* Racy check whether the huge page can be split */
2581 bool can_split_huge_page(struct page *page, int *pextra_pins)
2582 {
2583         int extra_pins;
2584
2585         /* Additional pins from page cache */
2586         if (PageAnon(page))
2587                 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2588         else
2589                 extra_pins = HPAGE_PMD_NR;
2590         if (pextra_pins)
2591                 *pextra_pins = extra_pins;
2592         return total_mapcount(page) == page_count(page) - extra_pins - 1;
2593 }
2594
2595 /*
2596  * This function splits huge page into normal pages. @page can point to any
2597  * subpage of huge page to split. Split doesn't change the position of @page.
2598  *
2599  * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2600  * The huge page must be locked.
2601  *
2602  * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2603  *
2604  * Both head page and tail pages will inherit mapping, flags, and so on from
2605  * the hugepage.
2606  *
2607  * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2608  * they are not mapped.
2609  *
2610  * Returns 0 if the hugepage is split successfully.
2611  * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2612  * us.
2613  */
2614 int split_huge_page_to_list(struct page *page, struct list_head *list)
2615 {
2616         struct page *head = compound_head(page);
2617         struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2618         struct anon_vma *anon_vma = NULL;
2619         struct address_space *mapping = NULL;
2620         int count, mapcount, extra_pins, ret;
2621         bool mlocked;
2622         unsigned long flags;
2623         pgoff_t end;
2624
2625         VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2626         VM_BUG_ON_PAGE(!PageLocked(page), page);
2627         VM_BUG_ON_PAGE(!PageCompound(page), page);
2628
2629         if (PageWriteback(page))
2630                 return -EBUSY;
2631
2632         if (PageAnon(head)) {
2633                 /*
2634                  * The caller does not necessarily hold an mmap_sem that would
2635                  * prevent the anon_vma disappearing so we first we take a
2636                  * reference to it and then lock the anon_vma for write. This
2637                  * is similar to page_lock_anon_vma_read except the write lock
2638                  * is taken to serialise against parallel split or collapse
2639                  * operations.
2640                  */
2641                 anon_vma = page_get_anon_vma(head);
2642                 if (!anon_vma) {
2643                         ret = -EBUSY;
2644                         goto out;
2645                 }
2646                 end = -1;
2647                 mapping = NULL;
2648                 anon_vma_lock_write(anon_vma);
2649         } else {
2650                 mapping = head->mapping;
2651
2652                 /* Truncated ? */
2653                 if (!mapping) {
2654                         ret = -EBUSY;
2655                         goto out;
2656                 }
2657
2658                 anon_vma = NULL;
2659                 i_mmap_lock_read(mapping);
2660
2661                 /*
2662                  *__split_huge_page() may need to trim off pages beyond EOF:
2663                  * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2664                  * which cannot be nested inside the page tree lock. So note
2665                  * end now: i_size itself may be changed at any moment, but
2666                  * head page lock is good enough to serialize the trimming.
2667                  */
2668                 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2669         }
2670
2671         /*
2672          * Racy check if we can split the page, before unmap_page() will
2673          * split PMDs
2674          */
2675         if (!can_split_huge_page(head, &extra_pins)) {
2676                 ret = -EBUSY;
2677                 goto out_unlock;
2678         }
2679
2680         mlocked = PageMlocked(page);
2681         unmap_page(head);
2682         VM_BUG_ON_PAGE(compound_mapcount(head), head);
2683
2684         /* Make sure the page is not on per-CPU pagevec as it takes pin */
2685         if (mlocked)
2686                 lru_add_drain();
2687
2688         /* prevent PageLRU to go away from under us, and freeze lru stats */
2689         spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2690
2691         if (mapping) {
2692                 XA_STATE(xas, &mapping->i_pages, page_index(head));
2693
2694                 /*
2695                  * Check if the head page is present in page cache.
2696                  * We assume all tail are present too, if head is there.
2697                  */
2698                 xa_lock(&mapping->i_pages);
2699                 if (xas_load(&xas) != head)
2700                         goto fail;
2701         }
2702
2703         /* Prevent deferred_split_scan() touching ->_refcount */
2704         spin_lock(&pgdata->split_queue_lock);
2705         count = page_count(head);
2706         mapcount = total_mapcount(head);
2707         if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2708                 if (!list_empty(page_deferred_list(head))) {
2709                         pgdata->split_queue_len--;
2710                         list_del(page_deferred_list(head));
2711                 }
2712                 if (mapping)
2713                         __dec_node_page_state(page, NR_SHMEM_THPS);
2714                 spin_unlock(&pgdata->split_queue_lock);
2715                 __split_huge_page(page, list, end, flags);
2716                 if (PageSwapCache(head)) {
2717                         swp_entry_t entry = { .val = page_private(head) };
2718
2719                         ret = split_swap_cluster(entry);
2720                 } else
2721                         ret = 0;
2722         } else {
2723                 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2724                         pr_alert("total_mapcount: %u, page_count(): %u\n",
2725                                         mapcount, count);
2726                         if (PageTail(page))
2727                                 dump_page(head, NULL);
2728                         dump_page(page, "total_mapcount(head) > 0");
2729                         BUG();
2730                 }
2731                 spin_unlock(&pgdata->split_queue_lock);
2732 fail:           if (mapping)
2733                         xa_unlock(&mapping->i_pages);
2734                 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2735                 remap_page(head);
2736                 ret = -EBUSY;
2737         }
2738
2739 out_unlock:
2740         if (anon_vma) {
2741                 anon_vma_unlock_write(anon_vma);
2742                 put_anon_vma(anon_vma);
2743         }
2744         if (mapping)
2745                 i_mmap_unlock_read(mapping);
2746 out:
2747         count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2748         return ret;
2749 }
2750
2751 void free_transhuge_page(struct page *page)
2752 {
2753         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2754         unsigned long flags;
2755
2756         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2757         if (!list_empty(page_deferred_list(page))) {
2758                 pgdata->split_queue_len--;
2759                 list_del(page_deferred_list(page));
2760         }
2761         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2762         free_compound_page(page);
2763 }
2764
2765 void deferred_split_huge_page(struct page *page)
2766 {
2767         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2768         unsigned long flags;
2769
2770         VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2771
2772         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2773         if (list_empty(page_deferred_list(page))) {
2774                 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2775                 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2776                 pgdata->split_queue_len++;
2777         }
2778         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2779 }
2780
2781 static unsigned long deferred_split_count(struct shrinker *shrink,
2782                 struct shrink_control *sc)
2783 {
2784         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2785         return READ_ONCE(pgdata->split_queue_len);
2786 }
2787
2788 static unsigned long deferred_split_scan(struct shrinker *shrink,
2789                 struct shrink_control *sc)
2790 {
2791         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2792         unsigned long flags;
2793         LIST_HEAD(list), *pos, *next;
2794         struct page *page;
2795         int split = 0;
2796
2797         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2798         /* Take pin on all head pages to avoid freeing them under us */
2799         list_for_each_safe(pos, next, &pgdata->split_queue) {
2800                 page = list_entry((void *)pos, struct page, mapping);
2801                 page = compound_head(page);
2802                 if (get_page_unless_zero(page)) {
2803                         list_move(page_deferred_list(page), &list);
2804                 } else {
2805                         /* We lost race with put_compound_page() */
2806                         list_del_init(page_deferred_list(page));
2807                         pgdata->split_queue_len--;
2808                 }
2809                 if (!--sc->nr_to_scan)
2810                         break;
2811         }
2812         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2813
2814         list_for_each_safe(pos, next, &list) {
2815                 page = list_entry((void *)pos, struct page, mapping);
2816                 if (!trylock_page(page))
2817                         goto next;
2818                 /* split_huge_page() removes page from list on success */
2819                 if (!split_huge_page(page))
2820                         split++;
2821                 unlock_page(page);
2822 next:
2823                 put_page(page);
2824         }
2825
2826         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2827         list_splice_tail(&list, &pgdata->split_queue);
2828         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2829
2830         /*
2831          * Stop shrinker if we didn't split any page, but the queue is empty.
2832          * This can happen if pages were freed under us.
2833          */
2834         if (!split && list_empty(&pgdata->split_queue))
2835                 return SHRINK_STOP;
2836         return split;
2837 }
2838
2839 static struct shrinker deferred_split_shrinker = {
2840         .count_objects = deferred_split_count,
2841         .scan_objects = deferred_split_scan,
2842         .seeks = DEFAULT_SEEKS,
2843         .flags = SHRINKER_NUMA_AWARE,
2844 };
2845
2846 #ifdef CONFIG_DEBUG_FS
2847 static int split_huge_pages_set(void *data, u64 val)
2848 {
2849         struct zone *zone;
2850         struct page *page;
2851         unsigned long pfn, max_zone_pfn;
2852         unsigned long total = 0, split = 0;
2853
2854         if (val != 1)
2855                 return -EINVAL;
2856
2857         for_each_populated_zone(zone) {
2858                 max_zone_pfn = zone_end_pfn(zone);
2859                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2860                         if (!pfn_valid(pfn))
2861                                 continue;
2862
2863                         page = pfn_to_page(pfn);
2864                         if (!get_page_unless_zero(page))
2865                                 continue;
2866
2867                         if (zone != page_zone(page))
2868                                 goto next;
2869
2870                         if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2871                                 goto next;
2872
2873                         total++;
2874                         lock_page(page);
2875                         if (!split_huge_page(page))
2876                                 split++;
2877                         unlock_page(page);
2878 next:
2879                         put_page(page);
2880                 }
2881         }
2882
2883         pr_info("%lu of %lu THP split\n", split, total);
2884
2885         return 0;
2886 }
2887 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2888                 "%llu\n");
2889
2890 static int __init split_huge_pages_debugfs(void)
2891 {
2892         debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2893                             &split_huge_pages_fops);
2894         return 0;
2895 }
2896 late_initcall(split_huge_pages_debugfs);
2897 #endif
2898
2899 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2900 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2901                 struct page *page)
2902 {
2903         struct vm_area_struct *vma = pvmw->vma;
2904         struct mm_struct *mm = vma->vm_mm;
2905         unsigned long address = pvmw->address;
2906         pmd_t pmdval;
2907         swp_entry_t entry;
2908         pmd_t pmdswp;
2909
2910         if (!(pvmw->pmd && !pvmw->pte))
2911                 return;
2912
2913         flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2914         pmdval = *pvmw->pmd;
2915         pmdp_invalidate(vma, address, pvmw->pmd);
2916         if (pmd_dirty(pmdval))
2917                 set_page_dirty(page);
2918         entry = make_migration_entry(page, pmd_write(pmdval));
2919         pmdswp = swp_entry_to_pmd(entry);
2920         if (pmd_soft_dirty(pmdval))
2921                 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2922         set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2923         page_remove_rmap(page, true);
2924         put_page(page);
2925 }
2926
2927 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2928 {
2929         struct vm_area_struct *vma = pvmw->vma;
2930         struct mm_struct *mm = vma->vm_mm;
2931         unsigned long address = pvmw->address;
2932         unsigned long mmun_start = address & HPAGE_PMD_MASK;
2933         pmd_t pmde;
2934         swp_entry_t entry;
2935
2936         if (!(pvmw->pmd && !pvmw->pte))
2937                 return;
2938
2939         entry = pmd_to_swp_entry(*pvmw->pmd);
2940         get_page(new);
2941         pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2942         if (pmd_swp_soft_dirty(*pvmw->pmd))
2943                 pmde = pmd_mksoft_dirty(pmde);
2944         if (is_write_migration_entry(entry))
2945                 pmde = maybe_pmd_mkwrite(pmde, vma);
2946
2947         flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2948         if (PageAnon(new))
2949                 page_add_anon_rmap(new, vma, mmun_start, true);
2950         else
2951                 page_add_file_rmap(new, true);
2952         set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2953         if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2954                 mlock_vma_page(new);
2955         update_mmu_cache_pmd(vma, address, pvmw->pmd);
2956 }
2957 #endif