vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems
[linux/fpc-iii.git] / mm / huge_memory.c
blob0e7ded98d114d184877d2fc9bd0f02c3187f2ed5
1 /*
2 * Copyright (C) 2009 Red Hat, Inc.
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 */
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
37 #include <asm/tlb.h>
38 #include <asm/pgalloc.h>
39 #include "internal.h"
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52 #endif
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55 #endif
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60 static struct shrinker deferred_split_shrinker;
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
65 static struct page *get_huge_zero_page(void)
67 struct page *zero_page;
68 retry:
69 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
70 return READ_ONCE(huge_zero_page);
72 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
73 HPAGE_PMD_ORDER);
74 if (!zero_page) {
75 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
76 return NULL;
78 count_vm_event(THP_ZERO_PAGE_ALLOC);
79 preempt_disable();
80 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
81 preempt_enable();
82 __free_pages(zero_page, compound_order(zero_page));
83 goto retry;
86 /* We take additional reference here. It will be put back by shrinker */
87 atomic_set(&huge_zero_refcount, 2);
88 preempt_enable();
89 return READ_ONCE(huge_zero_page);
92 static void put_huge_zero_page(void)
95 * Counter should never go to zero here. Only shrinker can put
96 * last reference.
98 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
101 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
103 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
104 return READ_ONCE(huge_zero_page);
106 if (!get_huge_zero_page())
107 return NULL;
109 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
110 put_huge_zero_page();
112 return READ_ONCE(huge_zero_page);
115 void mm_put_huge_zero_page(struct mm_struct *mm)
117 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
118 put_huge_zero_page();
121 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
122 struct shrink_control *sc)
124 /* we can free zero page only if last reference remains */
125 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
128 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
129 struct shrink_control *sc)
131 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
132 struct page *zero_page = xchg(&huge_zero_page, NULL);
133 BUG_ON(zero_page == NULL);
134 __free_pages(zero_page, compound_order(zero_page));
135 return HPAGE_PMD_NR;
138 return 0;
141 static struct shrinker huge_zero_page_shrinker = {
142 .count_objects = shrink_huge_zero_page_count,
143 .scan_objects = shrink_huge_zero_page_scan,
144 .seeks = DEFAULT_SEEKS,
147 #ifdef CONFIG_SYSFS
148 static ssize_t enabled_show(struct kobject *kobj,
149 struct kobj_attribute *attr, char *buf)
151 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
152 return sprintf(buf, "[always] madvise never\n");
153 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
154 return sprintf(buf, "always [madvise] never\n");
155 else
156 return sprintf(buf, "always madvise [never]\n");
159 static ssize_t enabled_store(struct kobject *kobj,
160 struct kobj_attribute *attr,
161 const char *buf, size_t count)
163 ssize_t ret = count;
165 if (!memcmp("always", buf,
166 min(sizeof("always")-1, count))) {
167 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
168 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
169 } else if (!memcmp("madvise", buf,
170 min(sizeof("madvise")-1, count))) {
171 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
172 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
173 } else if (!memcmp("never", buf,
174 min(sizeof("never")-1, count))) {
175 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
177 } else
178 ret = -EINVAL;
180 if (ret > 0) {
181 int err = start_stop_khugepaged();
182 if (err)
183 ret = err;
185 return ret;
187 static struct kobj_attribute enabled_attr =
188 __ATTR(enabled, 0644, enabled_show, enabled_store);
190 ssize_t single_hugepage_flag_show(struct kobject *kobj,
191 struct kobj_attribute *attr, char *buf,
192 enum transparent_hugepage_flag flag)
194 return sprintf(buf, "%d\n",
195 !!test_bit(flag, &transparent_hugepage_flags));
198 ssize_t single_hugepage_flag_store(struct kobject *kobj,
199 struct kobj_attribute *attr,
200 const char *buf, size_t count,
201 enum transparent_hugepage_flag flag)
203 unsigned long value;
204 int ret;
206 ret = kstrtoul(buf, 10, &value);
207 if (ret < 0)
208 return ret;
209 if (value > 1)
210 return -EINVAL;
212 if (value)
213 set_bit(flag, &transparent_hugepage_flags);
214 else
215 clear_bit(flag, &transparent_hugepage_flags);
217 return count;
220 static ssize_t defrag_show(struct kobject *kobj,
221 struct kobj_attribute *attr, char *buf)
223 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
224 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
225 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
226 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
227 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
228 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
229 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
230 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
231 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
234 static ssize_t defrag_store(struct kobject *kobj,
235 struct kobj_attribute *attr,
236 const char *buf, size_t count)
238 if (!memcmp("always", buf,
239 min(sizeof("always")-1, count))) {
240 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
241 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
242 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
243 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
244 } else if (!memcmp("defer+madvise", buf,
245 min(sizeof("defer+madvise")-1, count))) {
246 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
248 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
249 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
250 } else if (!memcmp("defer", buf,
251 min(sizeof("defer")-1, count))) {
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
255 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
256 } else if (!memcmp("madvise", buf,
257 min(sizeof("madvise")-1, count))) {
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
261 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
262 } else if (!memcmp("never", buf,
263 min(sizeof("never")-1, count))) {
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
268 } else
269 return -EINVAL;
271 return count;
273 static struct kobj_attribute defrag_attr =
274 __ATTR(defrag, 0644, defrag_show, defrag_store);
276 static ssize_t use_zero_page_show(struct kobject *kobj,
277 struct kobj_attribute *attr, char *buf)
279 return single_hugepage_flag_show(kobj, attr, buf,
280 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
282 static ssize_t use_zero_page_store(struct kobject *kobj,
283 struct kobj_attribute *attr, const char *buf, size_t count)
285 return single_hugepage_flag_store(kobj, attr, buf, count,
286 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
288 static struct kobj_attribute use_zero_page_attr =
289 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
291 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
292 struct kobj_attribute *attr, char *buf)
294 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
296 static struct kobj_attribute hpage_pmd_size_attr =
297 __ATTR_RO(hpage_pmd_size);
299 #ifdef CONFIG_DEBUG_VM
300 static ssize_t debug_cow_show(struct kobject *kobj,
301 struct kobj_attribute *attr, char *buf)
303 return single_hugepage_flag_show(kobj, attr, buf,
304 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
306 static ssize_t debug_cow_store(struct kobject *kobj,
307 struct kobj_attribute *attr,
308 const char *buf, size_t count)
310 return single_hugepage_flag_store(kobj, attr, buf, count,
311 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
313 static struct kobj_attribute debug_cow_attr =
314 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
315 #endif /* CONFIG_DEBUG_VM */
317 static struct attribute *hugepage_attr[] = {
318 &enabled_attr.attr,
319 &defrag_attr.attr,
320 &use_zero_page_attr.attr,
321 &hpage_pmd_size_attr.attr,
322 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
323 &shmem_enabled_attr.attr,
324 #endif
325 #ifdef CONFIG_DEBUG_VM
326 &debug_cow_attr.attr,
327 #endif
328 NULL,
331 static const struct attribute_group hugepage_attr_group = {
332 .attrs = hugepage_attr,
335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
337 int err;
339 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
340 if (unlikely(!*hugepage_kobj)) {
341 pr_err("failed to create transparent hugepage kobject\n");
342 return -ENOMEM;
345 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
346 if (err) {
347 pr_err("failed to register transparent hugepage group\n");
348 goto delete_obj;
351 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
352 if (err) {
353 pr_err("failed to register transparent hugepage group\n");
354 goto remove_hp_group;
357 return 0;
359 remove_hp_group:
360 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
361 delete_obj:
362 kobject_put(*hugepage_kobj);
363 return err;
366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
368 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
369 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
370 kobject_put(hugepage_kobj);
372 #else
373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
375 return 0;
378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
381 #endif /* CONFIG_SYSFS */
383 static int __init hugepage_init(void)
385 int err;
386 struct kobject *hugepage_kobj;
388 if (!has_transparent_hugepage()) {
389 transparent_hugepage_flags = 0;
390 return -EINVAL;
394 * hugepages can't be allocated by the buddy allocator
396 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
398 * we use page->mapping and page->index in second tail page
399 * as list_head: assuming THP order >= 2
401 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
403 err = hugepage_init_sysfs(&hugepage_kobj);
404 if (err)
405 goto err_sysfs;
407 err = khugepaged_init();
408 if (err)
409 goto err_slab;
411 err = register_shrinker(&huge_zero_page_shrinker);
412 if (err)
413 goto err_hzp_shrinker;
414 err = register_shrinker(&deferred_split_shrinker);
415 if (err)
416 goto err_split_shrinker;
419 * By default disable transparent hugepages on smaller systems,
420 * where the extra memory used could hurt more than TLB overhead
421 * is likely to save. The admin can still enable it through /sys.
423 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
424 transparent_hugepage_flags = 0;
425 return 0;
428 err = start_stop_khugepaged();
429 if (err)
430 goto err_khugepaged;
432 return 0;
433 err_khugepaged:
434 unregister_shrinker(&deferred_split_shrinker);
435 err_split_shrinker:
436 unregister_shrinker(&huge_zero_page_shrinker);
437 err_hzp_shrinker:
438 khugepaged_destroy();
439 err_slab:
440 hugepage_exit_sysfs(hugepage_kobj);
441 err_sysfs:
442 return err;
444 subsys_initcall(hugepage_init);
446 static int __init setup_transparent_hugepage(char *str)
448 int ret = 0;
449 if (!str)
450 goto out;
451 if (!strcmp(str, "always")) {
452 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
453 &transparent_hugepage_flags);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
455 &transparent_hugepage_flags);
456 ret = 1;
457 } else if (!strcmp(str, "madvise")) {
458 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
459 &transparent_hugepage_flags);
460 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
461 &transparent_hugepage_flags);
462 ret = 1;
463 } else if (!strcmp(str, "never")) {
464 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
465 &transparent_hugepage_flags);
466 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
467 &transparent_hugepage_flags);
468 ret = 1;
470 out:
471 if (!ret)
472 pr_warn("transparent_hugepage= cannot parse, ignored\n");
473 return ret;
475 __setup("transparent_hugepage=", setup_transparent_hugepage);
477 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
479 if (likely(vma->vm_flags & VM_WRITE))
480 pmd = pmd_mkwrite(pmd);
481 return pmd;
484 static inline struct list_head *page_deferred_list(struct page *page)
487 * ->lru in the tail pages is occupied by compound_head.
488 * Let's use ->mapping + ->index in the second tail page as list_head.
490 return (struct list_head *)&page[2].mapping;
493 void prep_transhuge_page(struct page *page)
496 * we use page->mapping and page->indexlru in second tail page
497 * as list_head: assuming THP order >= 2
500 INIT_LIST_HEAD(page_deferred_list(page));
501 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
504 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
505 loff_t off, unsigned long flags, unsigned long size)
507 unsigned long addr;
508 loff_t off_end = off + len;
509 loff_t off_align = round_up(off, size);
510 unsigned long len_pad;
512 if (off_end <= off_align || (off_end - off_align) < size)
513 return 0;
515 len_pad = len + size;
516 if (len_pad < len || (off + len_pad) < off)
517 return 0;
519 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
520 off >> PAGE_SHIFT, flags);
521 if (IS_ERR_VALUE(addr))
522 return 0;
524 addr += (off - addr) & (size - 1);
525 return addr;
528 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
529 unsigned long len, unsigned long pgoff, unsigned long flags)
531 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
533 if (addr)
534 goto out;
535 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
536 goto out;
538 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
539 if (addr)
540 return addr;
542 out:
543 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
545 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
547 static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
548 gfp_t gfp)
550 struct vm_area_struct *vma = vmf->vma;
551 struct mem_cgroup *memcg;
552 pgtable_t pgtable;
553 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
554 int ret = 0;
556 VM_BUG_ON_PAGE(!PageCompound(page), page);
558 if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
559 put_page(page);
560 count_vm_event(THP_FAULT_FALLBACK);
561 return VM_FAULT_FALLBACK;
564 pgtable = pte_alloc_one(vma->vm_mm, haddr);
565 if (unlikely(!pgtable)) {
566 ret = VM_FAULT_OOM;
567 goto release;
570 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
572 * The memory barrier inside __SetPageUptodate makes sure that
573 * clear_huge_page writes become visible before the set_pmd_at()
574 * write.
576 __SetPageUptodate(page);
578 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
579 if (unlikely(!pmd_none(*vmf->pmd))) {
580 goto unlock_release;
581 } else {
582 pmd_t entry;
584 ret = check_stable_address_space(vma->vm_mm);
585 if (ret)
586 goto unlock_release;
588 /* Deliver the page fault to userland */
589 if (userfaultfd_missing(vma)) {
590 int ret;
592 spin_unlock(vmf->ptl);
593 mem_cgroup_cancel_charge(page, memcg, true);
594 put_page(page);
595 pte_free(vma->vm_mm, pgtable);
596 ret = handle_userfault(vmf, VM_UFFD_MISSING);
597 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
598 return ret;
601 entry = mk_huge_pmd(page, vma->vm_page_prot);
602 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
603 page_add_new_anon_rmap(page, vma, haddr, true);
604 mem_cgroup_commit_charge(page, memcg, false, true);
605 lru_cache_add_active_or_unevictable(page, vma);
606 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
607 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
608 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
609 mm_inc_nr_ptes(vma->vm_mm);
610 spin_unlock(vmf->ptl);
611 count_vm_event(THP_FAULT_ALLOC);
614 return 0;
615 unlock_release:
616 spin_unlock(vmf->ptl);
617 release:
618 if (pgtable)
619 pte_free(vma->vm_mm, pgtable);
620 mem_cgroup_cancel_charge(page, memcg, true);
621 put_page(page);
622 return ret;
627 * always: directly stall for all thp allocations
628 * defer: wake kswapd and fail if not immediately available
629 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
630 * fail if not immediately available
631 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
632 * available
633 * never: never stall for any thp allocation
635 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
637 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
639 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
640 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
641 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
642 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
643 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
644 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
645 __GFP_KSWAPD_RECLAIM);
646 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
647 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
649 return GFP_TRANSHUGE_LIGHT;
652 /* Caller must hold page table lock. */
653 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
654 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
655 struct page *zero_page)
657 pmd_t entry;
658 if (!pmd_none(*pmd))
659 return false;
660 entry = mk_pmd(zero_page, vma->vm_page_prot);
661 entry = pmd_mkhuge(entry);
662 if (pgtable)
663 pgtable_trans_huge_deposit(mm, pmd, pgtable);
664 set_pmd_at(mm, haddr, pmd, entry);
665 mm_inc_nr_ptes(mm);
666 return true;
669 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
671 struct vm_area_struct *vma = vmf->vma;
672 gfp_t gfp;
673 struct page *page;
674 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
676 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
677 return VM_FAULT_FALLBACK;
678 if (unlikely(anon_vma_prepare(vma)))
679 return VM_FAULT_OOM;
680 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
681 return VM_FAULT_OOM;
682 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
683 !mm_forbids_zeropage(vma->vm_mm) &&
684 transparent_hugepage_use_zero_page()) {
685 pgtable_t pgtable;
686 struct page *zero_page;
687 bool set;
688 int ret;
689 pgtable = pte_alloc_one(vma->vm_mm, haddr);
690 if (unlikely(!pgtable))
691 return VM_FAULT_OOM;
692 zero_page = mm_get_huge_zero_page(vma->vm_mm);
693 if (unlikely(!zero_page)) {
694 pte_free(vma->vm_mm, pgtable);
695 count_vm_event(THP_FAULT_FALLBACK);
696 return VM_FAULT_FALLBACK;
698 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
699 ret = 0;
700 set = false;
701 if (pmd_none(*vmf->pmd)) {
702 ret = check_stable_address_space(vma->vm_mm);
703 if (ret) {
704 spin_unlock(vmf->ptl);
705 } else if (userfaultfd_missing(vma)) {
706 spin_unlock(vmf->ptl);
707 ret = handle_userfault(vmf, VM_UFFD_MISSING);
708 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
709 } else {
710 set_huge_zero_page(pgtable, vma->vm_mm, vma,
711 haddr, vmf->pmd, zero_page);
712 spin_unlock(vmf->ptl);
713 set = true;
715 } else
716 spin_unlock(vmf->ptl);
717 if (!set)
718 pte_free(vma->vm_mm, pgtable);
719 return ret;
721 gfp = alloc_hugepage_direct_gfpmask(vma);
722 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
723 if (unlikely(!page)) {
724 count_vm_event(THP_FAULT_FALLBACK);
725 return VM_FAULT_FALLBACK;
727 prep_transhuge_page(page);
728 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
731 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
732 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
733 pgtable_t pgtable)
735 struct mm_struct *mm = vma->vm_mm;
736 pmd_t entry;
737 spinlock_t *ptl;
739 ptl = pmd_lock(mm, pmd);
740 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
741 if (pfn_t_devmap(pfn))
742 entry = pmd_mkdevmap(entry);
743 if (write) {
744 entry = pmd_mkyoung(pmd_mkdirty(entry));
745 entry = maybe_pmd_mkwrite(entry, vma);
748 if (pgtable) {
749 pgtable_trans_huge_deposit(mm, pmd, pgtable);
750 mm_inc_nr_ptes(mm);
753 set_pmd_at(mm, addr, pmd, entry);
754 update_mmu_cache_pmd(vma, addr, pmd);
755 spin_unlock(ptl);
758 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
759 pmd_t *pmd, pfn_t pfn, bool write)
761 pgprot_t pgprot = vma->vm_page_prot;
762 pgtable_t pgtable = NULL;
764 * If we had pmd_special, we could avoid all these restrictions,
765 * but we need to be consistent with PTEs and architectures that
766 * can't support a 'special' bit.
768 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
769 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
770 (VM_PFNMAP|VM_MIXEDMAP));
771 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
772 BUG_ON(!pfn_t_devmap(pfn));
774 if (addr < vma->vm_start || addr >= vma->vm_end)
775 return VM_FAULT_SIGBUS;
777 if (arch_needs_pgtable_deposit()) {
778 pgtable = pte_alloc_one(vma->vm_mm, addr);
779 if (!pgtable)
780 return VM_FAULT_OOM;
783 track_pfn_insert(vma, &pgprot, pfn);
785 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
786 return VM_FAULT_NOPAGE;
788 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
790 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
791 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
793 if (likely(vma->vm_flags & VM_WRITE))
794 pud = pud_mkwrite(pud);
795 return pud;
798 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
799 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
801 struct mm_struct *mm = vma->vm_mm;
802 pud_t entry;
803 spinlock_t *ptl;
805 ptl = pud_lock(mm, pud);
806 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
807 if (pfn_t_devmap(pfn))
808 entry = pud_mkdevmap(entry);
809 if (write) {
810 entry = pud_mkyoung(pud_mkdirty(entry));
811 entry = maybe_pud_mkwrite(entry, vma);
813 set_pud_at(mm, addr, pud, entry);
814 update_mmu_cache_pud(vma, addr, pud);
815 spin_unlock(ptl);
818 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
819 pud_t *pud, pfn_t pfn, bool write)
821 pgprot_t pgprot = vma->vm_page_prot;
823 * If we had pud_special, we could avoid all these restrictions,
824 * but we need to be consistent with PTEs and architectures that
825 * can't support a 'special' bit.
827 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
828 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
829 (VM_PFNMAP|VM_MIXEDMAP));
830 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
831 BUG_ON(!pfn_t_devmap(pfn));
833 if (addr < vma->vm_start || addr >= vma->vm_end)
834 return VM_FAULT_SIGBUS;
836 track_pfn_insert(vma, &pgprot, pfn);
838 insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
839 return VM_FAULT_NOPAGE;
841 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
842 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
844 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
845 pmd_t *pmd, int flags)
847 pmd_t _pmd;
849 _pmd = pmd_mkyoung(*pmd);
850 if (flags & FOLL_WRITE)
851 _pmd = pmd_mkdirty(_pmd);
852 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
853 pmd, _pmd, flags & FOLL_WRITE))
854 update_mmu_cache_pmd(vma, addr, pmd);
857 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
858 pmd_t *pmd, int flags)
860 unsigned long pfn = pmd_pfn(*pmd);
861 struct mm_struct *mm = vma->vm_mm;
862 struct dev_pagemap *pgmap;
863 struct page *page;
865 assert_spin_locked(pmd_lockptr(mm, pmd));
868 * When we COW a devmap PMD entry, we split it into PTEs, so we should
869 * not be in this function with `flags & FOLL_COW` set.
871 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
873 if (flags & FOLL_WRITE && !pmd_write(*pmd))
874 return NULL;
876 if (pmd_present(*pmd) && pmd_devmap(*pmd))
877 /* pass */;
878 else
879 return NULL;
881 if (flags & FOLL_TOUCH)
882 touch_pmd(vma, addr, pmd, flags);
885 * device mapped pages can only be returned if the
886 * caller will manage the page reference count.
888 if (!(flags & FOLL_GET))
889 return ERR_PTR(-EEXIST);
891 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
892 pgmap = get_dev_pagemap(pfn, NULL);
893 if (!pgmap)
894 return ERR_PTR(-EFAULT);
895 page = pfn_to_page(pfn);
896 get_page(page);
897 put_dev_pagemap(pgmap);
899 return page;
902 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
903 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
904 struct vm_area_struct *vma)
906 spinlock_t *dst_ptl, *src_ptl;
907 struct page *src_page;
908 pmd_t pmd;
909 pgtable_t pgtable = NULL;
910 int ret = -ENOMEM;
912 /* Skip if can be re-fill on fault */
913 if (!vma_is_anonymous(vma))
914 return 0;
916 pgtable = pte_alloc_one(dst_mm, addr);
917 if (unlikely(!pgtable))
918 goto out;
920 dst_ptl = pmd_lock(dst_mm, dst_pmd);
921 src_ptl = pmd_lockptr(src_mm, src_pmd);
922 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
924 ret = -EAGAIN;
925 pmd = *src_pmd;
927 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
928 if (unlikely(is_swap_pmd(pmd))) {
929 swp_entry_t entry = pmd_to_swp_entry(pmd);
931 VM_BUG_ON(!is_pmd_migration_entry(pmd));
932 if (is_write_migration_entry(entry)) {
933 make_migration_entry_read(&entry);
934 pmd = swp_entry_to_pmd(entry);
935 if (pmd_swp_soft_dirty(*src_pmd))
936 pmd = pmd_swp_mksoft_dirty(pmd);
937 set_pmd_at(src_mm, addr, src_pmd, pmd);
939 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
940 mm_inc_nr_ptes(dst_mm);
941 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
942 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
943 ret = 0;
944 goto out_unlock;
946 #endif
948 if (unlikely(!pmd_trans_huge(pmd))) {
949 pte_free(dst_mm, pgtable);
950 goto out_unlock;
953 * When page table lock is held, the huge zero pmd should not be
954 * under splitting since we don't split the page itself, only pmd to
955 * a page table.
957 if (is_huge_zero_pmd(pmd)) {
958 struct page *zero_page;
960 * get_huge_zero_page() will never allocate a new page here,
961 * since we already have a zero page to copy. It just takes a
962 * reference.
964 zero_page = mm_get_huge_zero_page(dst_mm);
965 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
966 zero_page);
967 ret = 0;
968 goto out_unlock;
971 src_page = pmd_page(pmd);
972 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
973 get_page(src_page);
974 page_dup_rmap(src_page, true);
975 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
976 mm_inc_nr_ptes(dst_mm);
977 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
979 pmdp_set_wrprotect(src_mm, addr, src_pmd);
980 pmd = pmd_mkold(pmd_wrprotect(pmd));
981 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
983 ret = 0;
984 out_unlock:
985 spin_unlock(src_ptl);
986 spin_unlock(dst_ptl);
987 out:
988 return ret;
991 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
992 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
993 pud_t *pud, int flags)
995 pud_t _pud;
997 _pud = pud_mkyoung(*pud);
998 if (flags & FOLL_WRITE)
999 _pud = pud_mkdirty(_pud);
1000 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1001 pud, _pud, flags & FOLL_WRITE))
1002 update_mmu_cache_pud(vma, addr, pud);
1005 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1006 pud_t *pud, int flags)
1008 unsigned long pfn = pud_pfn(*pud);
1009 struct mm_struct *mm = vma->vm_mm;
1010 struct dev_pagemap *pgmap;
1011 struct page *page;
1013 assert_spin_locked(pud_lockptr(mm, pud));
1015 if (flags & FOLL_WRITE && !pud_write(*pud))
1016 return NULL;
1018 if (pud_present(*pud) && pud_devmap(*pud))
1019 /* pass */;
1020 else
1021 return NULL;
1023 if (flags & FOLL_TOUCH)
1024 touch_pud(vma, addr, pud, flags);
1027 * device mapped pages can only be returned if the
1028 * caller will manage the page reference count.
1030 if (!(flags & FOLL_GET))
1031 return ERR_PTR(-EEXIST);
1033 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1034 pgmap = get_dev_pagemap(pfn, NULL);
1035 if (!pgmap)
1036 return ERR_PTR(-EFAULT);
1037 page = pfn_to_page(pfn);
1038 get_page(page);
1039 put_dev_pagemap(pgmap);
1041 return page;
1044 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1045 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1046 struct vm_area_struct *vma)
1048 spinlock_t *dst_ptl, *src_ptl;
1049 pud_t pud;
1050 int ret;
1052 dst_ptl = pud_lock(dst_mm, dst_pud);
1053 src_ptl = pud_lockptr(src_mm, src_pud);
1054 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1056 ret = -EAGAIN;
1057 pud = *src_pud;
1058 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1059 goto out_unlock;
1062 * When page table lock is held, the huge zero pud should not be
1063 * under splitting since we don't split the page itself, only pud to
1064 * a page table.
1066 if (is_huge_zero_pud(pud)) {
1067 /* No huge zero pud yet */
1070 pudp_set_wrprotect(src_mm, addr, src_pud);
1071 pud = pud_mkold(pud_wrprotect(pud));
1072 set_pud_at(dst_mm, addr, dst_pud, pud);
1074 ret = 0;
1075 out_unlock:
1076 spin_unlock(src_ptl);
1077 spin_unlock(dst_ptl);
1078 return ret;
1081 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1083 pud_t entry;
1084 unsigned long haddr;
1085 bool write = vmf->flags & FAULT_FLAG_WRITE;
1087 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1088 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1089 goto unlock;
1091 entry = pud_mkyoung(orig_pud);
1092 if (write)
1093 entry = pud_mkdirty(entry);
1094 haddr = vmf->address & HPAGE_PUD_MASK;
1095 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1096 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1098 unlock:
1099 spin_unlock(vmf->ptl);
1101 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1103 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1105 pmd_t entry;
1106 unsigned long haddr;
1107 bool write = vmf->flags & FAULT_FLAG_WRITE;
1109 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1110 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1111 goto unlock;
1113 entry = pmd_mkyoung(orig_pmd);
1114 if (write)
1115 entry = pmd_mkdirty(entry);
1116 haddr = vmf->address & HPAGE_PMD_MASK;
1117 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1118 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1120 unlock:
1121 spin_unlock(vmf->ptl);
1124 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1125 struct page *page)
1127 struct vm_area_struct *vma = vmf->vma;
1128 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1129 struct mem_cgroup *memcg;
1130 pgtable_t pgtable;
1131 pmd_t _pmd;
1132 int ret = 0, i;
1133 struct page **pages;
1134 unsigned long mmun_start; /* For mmu_notifiers */
1135 unsigned long mmun_end; /* For mmu_notifiers */
1137 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1138 GFP_KERNEL);
1139 if (unlikely(!pages)) {
1140 ret |= VM_FAULT_OOM;
1141 goto out;
1144 for (i = 0; i < HPAGE_PMD_NR; i++) {
1145 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1146 vmf->address, page_to_nid(page));
1147 if (unlikely(!pages[i] ||
1148 mem_cgroup_try_charge(pages[i], vma->vm_mm,
1149 GFP_KERNEL, &memcg, false))) {
1150 if (pages[i])
1151 put_page(pages[i]);
1152 while (--i >= 0) {
1153 memcg = (void *)page_private(pages[i]);
1154 set_page_private(pages[i], 0);
1155 mem_cgroup_cancel_charge(pages[i], memcg,
1156 false);
1157 put_page(pages[i]);
1159 kfree(pages);
1160 ret |= VM_FAULT_OOM;
1161 goto out;
1163 set_page_private(pages[i], (unsigned long)memcg);
1166 for (i = 0; i < HPAGE_PMD_NR; i++) {
1167 copy_user_highpage(pages[i], page + i,
1168 haddr + PAGE_SIZE * i, vma);
1169 __SetPageUptodate(pages[i]);
1170 cond_resched();
1173 mmun_start = haddr;
1174 mmun_end = haddr + HPAGE_PMD_SIZE;
1175 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1177 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1178 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1179 goto out_free_pages;
1180 VM_BUG_ON_PAGE(!PageHead(page), page);
1183 * Leave pmd empty until pte is filled note we must notify here as
1184 * concurrent CPU thread might write to new page before the call to
1185 * mmu_notifier_invalidate_range_end() happens which can lead to a
1186 * device seeing memory write in different order than CPU.
1188 * See Documentation/vm/mmu_notifier.txt
1190 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1192 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1193 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1195 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1196 pte_t entry;
1197 entry = mk_pte(pages[i], vma->vm_page_prot);
1198 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1199 memcg = (void *)page_private(pages[i]);
1200 set_page_private(pages[i], 0);
1201 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1202 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1203 lru_cache_add_active_or_unevictable(pages[i], vma);
1204 vmf->pte = pte_offset_map(&_pmd, haddr);
1205 VM_BUG_ON(!pte_none(*vmf->pte));
1206 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1207 pte_unmap(vmf->pte);
1209 kfree(pages);
1211 smp_wmb(); /* make pte visible before pmd */
1212 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1213 page_remove_rmap(page, true);
1214 spin_unlock(vmf->ptl);
1217 * No need to double call mmu_notifier->invalidate_range() callback as
1218 * the above pmdp_huge_clear_flush_notify() did already call it.
1220 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1221 mmun_end);
1223 ret |= VM_FAULT_WRITE;
1224 put_page(page);
1226 out:
1227 return ret;
1229 out_free_pages:
1230 spin_unlock(vmf->ptl);
1231 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1232 for (i = 0; i < HPAGE_PMD_NR; i++) {
1233 memcg = (void *)page_private(pages[i]);
1234 set_page_private(pages[i], 0);
1235 mem_cgroup_cancel_charge(pages[i], memcg, false);
1236 put_page(pages[i]);
1238 kfree(pages);
1239 goto out;
1242 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1244 struct vm_area_struct *vma = vmf->vma;
1245 struct page *page = NULL, *new_page;
1246 struct mem_cgroup *memcg;
1247 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1248 unsigned long mmun_start; /* For mmu_notifiers */
1249 unsigned long mmun_end; /* For mmu_notifiers */
1250 gfp_t huge_gfp; /* for allocation and charge */
1251 int ret = 0;
1253 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1254 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1255 if (is_huge_zero_pmd(orig_pmd))
1256 goto alloc;
1257 spin_lock(vmf->ptl);
1258 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1259 goto out_unlock;
1261 page = pmd_page(orig_pmd);
1262 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1264 * We can only reuse the page if nobody else maps the huge page or it's
1265 * part.
1267 if (!trylock_page(page)) {
1268 get_page(page);
1269 spin_unlock(vmf->ptl);
1270 lock_page(page);
1271 spin_lock(vmf->ptl);
1272 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1273 unlock_page(page);
1274 put_page(page);
1275 goto out_unlock;
1277 put_page(page);
1279 if (reuse_swap_page(page, NULL)) {
1280 pmd_t entry;
1281 entry = pmd_mkyoung(orig_pmd);
1282 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1283 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1284 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1285 ret |= VM_FAULT_WRITE;
1286 unlock_page(page);
1287 goto out_unlock;
1289 unlock_page(page);
1290 get_page(page);
1291 spin_unlock(vmf->ptl);
1292 alloc:
1293 if (transparent_hugepage_enabled(vma) &&
1294 !transparent_hugepage_debug_cow()) {
1295 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1296 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1297 } else
1298 new_page = NULL;
1300 if (likely(new_page)) {
1301 prep_transhuge_page(new_page);
1302 } else {
1303 if (!page) {
1304 split_huge_pmd(vma, vmf->pmd, vmf->address);
1305 ret |= VM_FAULT_FALLBACK;
1306 } else {
1307 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1308 if (ret & VM_FAULT_OOM) {
1309 split_huge_pmd(vma, vmf->pmd, vmf->address);
1310 ret |= VM_FAULT_FALLBACK;
1312 put_page(page);
1314 count_vm_event(THP_FAULT_FALLBACK);
1315 goto out;
1318 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1319 huge_gfp, &memcg, true))) {
1320 put_page(new_page);
1321 split_huge_pmd(vma, vmf->pmd, vmf->address);
1322 if (page)
1323 put_page(page);
1324 ret |= VM_FAULT_FALLBACK;
1325 count_vm_event(THP_FAULT_FALLBACK);
1326 goto out;
1329 count_vm_event(THP_FAULT_ALLOC);
1331 if (!page)
1332 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1333 else
1334 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1335 __SetPageUptodate(new_page);
1337 mmun_start = haddr;
1338 mmun_end = haddr + HPAGE_PMD_SIZE;
1339 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1341 spin_lock(vmf->ptl);
1342 if (page)
1343 put_page(page);
1344 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1345 spin_unlock(vmf->ptl);
1346 mem_cgroup_cancel_charge(new_page, memcg, true);
1347 put_page(new_page);
1348 goto out_mn;
1349 } else {
1350 pmd_t entry;
1351 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1352 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1353 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1354 page_add_new_anon_rmap(new_page, vma, haddr, true);
1355 mem_cgroup_commit_charge(new_page, memcg, false, true);
1356 lru_cache_add_active_or_unevictable(new_page, vma);
1357 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1358 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1359 if (!page) {
1360 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1361 } else {
1362 VM_BUG_ON_PAGE(!PageHead(page), page);
1363 page_remove_rmap(page, true);
1364 put_page(page);
1366 ret |= VM_FAULT_WRITE;
1368 spin_unlock(vmf->ptl);
1369 out_mn:
1371 * No need to double call mmu_notifier->invalidate_range() callback as
1372 * the above pmdp_huge_clear_flush_notify() did already call it.
1374 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1375 mmun_end);
1376 out:
1377 return ret;
1378 out_unlock:
1379 spin_unlock(vmf->ptl);
1380 return ret;
1384 * FOLL_FORCE can write to even unwritable pmd's, but only
1385 * after we've gone through a COW cycle and they are dirty.
1387 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1389 return pmd_write(pmd) ||
1390 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1393 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1394 unsigned long addr,
1395 pmd_t *pmd,
1396 unsigned int flags)
1398 struct mm_struct *mm = vma->vm_mm;
1399 struct page *page = NULL;
1401 assert_spin_locked(pmd_lockptr(mm, pmd));
1403 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1404 goto out;
1406 /* Avoid dumping huge zero page */
1407 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1408 return ERR_PTR(-EFAULT);
1410 /* Full NUMA hinting faults to serialise migration in fault paths */
1411 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1412 goto out;
1414 page = pmd_page(*pmd);
1415 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1416 if (flags & FOLL_TOUCH)
1417 touch_pmd(vma, addr, pmd, flags);
1418 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1420 * We don't mlock() pte-mapped THPs. This way we can avoid
1421 * leaking mlocked pages into non-VM_LOCKED VMAs.
1423 * For anon THP:
1425 * In most cases the pmd is the only mapping of the page as we
1426 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1427 * writable private mappings in populate_vma_page_range().
1429 * The only scenario when we have the page shared here is if we
1430 * mlocking read-only mapping shared over fork(). We skip
1431 * mlocking such pages.
1433 * For file THP:
1435 * We can expect PageDoubleMap() to be stable under page lock:
1436 * for file pages we set it in page_add_file_rmap(), which
1437 * requires page to be locked.
1440 if (PageAnon(page) && compound_mapcount(page) != 1)
1441 goto skip_mlock;
1442 if (PageDoubleMap(page) || !page->mapping)
1443 goto skip_mlock;
1444 if (!trylock_page(page))
1445 goto skip_mlock;
1446 lru_add_drain();
1447 if (page->mapping && !PageDoubleMap(page))
1448 mlock_vma_page(page);
1449 unlock_page(page);
1451 skip_mlock:
1452 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1453 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1454 if (flags & FOLL_GET)
1455 get_page(page);
1457 out:
1458 return page;
1461 /* NUMA hinting page fault entry point for trans huge pmds */
1462 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1464 struct vm_area_struct *vma = vmf->vma;
1465 struct anon_vma *anon_vma = NULL;
1466 struct page *page;
1467 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1468 int page_nid = -1, this_nid = numa_node_id();
1469 int target_nid, last_cpupid = -1;
1470 bool page_locked;
1471 bool migrated = false;
1472 bool was_writable;
1473 int flags = 0;
1475 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1476 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1477 goto out_unlock;
1480 * If there are potential migrations, wait for completion and retry
1481 * without disrupting NUMA hinting information. Do not relock and
1482 * check_same as the page may no longer be mapped.
1484 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1485 page = pmd_page(*vmf->pmd);
1486 if (!get_page_unless_zero(page))
1487 goto out_unlock;
1488 spin_unlock(vmf->ptl);
1489 wait_on_page_locked(page);
1490 put_page(page);
1491 goto out;
1494 page = pmd_page(pmd);
1495 BUG_ON(is_huge_zero_page(page));
1496 page_nid = page_to_nid(page);
1497 last_cpupid = page_cpupid_last(page);
1498 count_vm_numa_event(NUMA_HINT_FAULTS);
1499 if (page_nid == this_nid) {
1500 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1501 flags |= TNF_FAULT_LOCAL;
1504 /* See similar comment in do_numa_page for explanation */
1505 if (!pmd_savedwrite(pmd))
1506 flags |= TNF_NO_GROUP;
1509 * Acquire the page lock to serialise THP migrations but avoid dropping
1510 * page_table_lock if at all possible
1512 page_locked = trylock_page(page);
1513 target_nid = mpol_misplaced(page, vma, haddr);
1514 if (target_nid == -1) {
1515 /* If the page was locked, there are no parallel migrations */
1516 if (page_locked)
1517 goto clear_pmdnuma;
1520 /* Migration could have started since the pmd_trans_migrating check */
1521 if (!page_locked) {
1522 page_nid = -1;
1523 if (!get_page_unless_zero(page))
1524 goto out_unlock;
1525 spin_unlock(vmf->ptl);
1526 wait_on_page_locked(page);
1527 put_page(page);
1528 goto out;
1532 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1533 * to serialises splits
1535 get_page(page);
1536 spin_unlock(vmf->ptl);
1537 anon_vma = page_lock_anon_vma_read(page);
1539 /* Confirm the PMD did not change while page_table_lock was released */
1540 spin_lock(vmf->ptl);
1541 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1542 unlock_page(page);
1543 put_page(page);
1544 page_nid = -1;
1545 goto out_unlock;
1548 /* Bail if we fail to protect against THP splits for any reason */
1549 if (unlikely(!anon_vma)) {
1550 put_page(page);
1551 page_nid = -1;
1552 goto clear_pmdnuma;
1556 * Since we took the NUMA fault, we must have observed the !accessible
1557 * bit. Make sure all other CPUs agree with that, to avoid them
1558 * modifying the page we're about to migrate.
1560 * Must be done under PTL such that we'll observe the relevant
1561 * inc_tlb_flush_pending().
1563 * We are not sure a pending tlb flush here is for a huge page
1564 * mapping or not. Hence use the tlb range variant
1566 if (mm_tlb_flush_pending(vma->vm_mm))
1567 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1570 * Migrate the THP to the requested node, returns with page unlocked
1571 * and access rights restored.
1573 spin_unlock(vmf->ptl);
1575 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1576 vmf->pmd, pmd, vmf->address, page, target_nid);
1577 if (migrated) {
1578 flags |= TNF_MIGRATED;
1579 page_nid = target_nid;
1580 } else
1581 flags |= TNF_MIGRATE_FAIL;
1583 goto out;
1584 clear_pmdnuma:
1585 BUG_ON(!PageLocked(page));
1586 was_writable = pmd_savedwrite(pmd);
1587 pmd = pmd_modify(pmd, vma->vm_page_prot);
1588 pmd = pmd_mkyoung(pmd);
1589 if (was_writable)
1590 pmd = pmd_mkwrite(pmd);
1591 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1592 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1593 unlock_page(page);
1594 out_unlock:
1595 spin_unlock(vmf->ptl);
1597 out:
1598 if (anon_vma)
1599 page_unlock_anon_vma_read(anon_vma);
1601 if (page_nid != -1)
1602 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1603 flags);
1605 return 0;
1609 * Return true if we do MADV_FREE successfully on entire pmd page.
1610 * Otherwise, return false.
1612 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1613 pmd_t *pmd, unsigned long addr, unsigned long next)
1615 spinlock_t *ptl;
1616 pmd_t orig_pmd;
1617 struct page *page;
1618 struct mm_struct *mm = tlb->mm;
1619 bool ret = false;
1621 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1623 ptl = pmd_trans_huge_lock(pmd, vma);
1624 if (!ptl)
1625 goto out_unlocked;
1627 orig_pmd = *pmd;
1628 if (is_huge_zero_pmd(orig_pmd))
1629 goto out;
1631 if (unlikely(!pmd_present(orig_pmd))) {
1632 VM_BUG_ON(thp_migration_supported() &&
1633 !is_pmd_migration_entry(orig_pmd));
1634 goto out;
1637 page = pmd_page(orig_pmd);
1639 * If other processes are mapping this page, we couldn't discard
1640 * the page unless they all do MADV_FREE so let's skip the page.
1642 if (page_mapcount(page) != 1)
1643 goto out;
1645 if (!trylock_page(page))
1646 goto out;
1649 * If user want to discard part-pages of THP, split it so MADV_FREE
1650 * will deactivate only them.
1652 if (next - addr != HPAGE_PMD_SIZE) {
1653 get_page(page);
1654 spin_unlock(ptl);
1655 split_huge_page(page);
1656 unlock_page(page);
1657 put_page(page);
1658 goto out_unlocked;
1661 if (PageDirty(page))
1662 ClearPageDirty(page);
1663 unlock_page(page);
1665 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1666 pmdp_invalidate(vma, addr, pmd);
1667 orig_pmd = pmd_mkold(orig_pmd);
1668 orig_pmd = pmd_mkclean(orig_pmd);
1670 set_pmd_at(mm, addr, pmd, orig_pmd);
1671 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1674 mark_page_lazyfree(page);
1675 ret = true;
1676 out:
1677 spin_unlock(ptl);
1678 out_unlocked:
1679 return ret;
1682 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1684 pgtable_t pgtable;
1686 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1687 pte_free(mm, pgtable);
1688 mm_dec_nr_ptes(mm);
1691 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1692 pmd_t *pmd, unsigned long addr)
1694 pmd_t orig_pmd;
1695 spinlock_t *ptl;
1697 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1699 ptl = __pmd_trans_huge_lock(pmd, vma);
1700 if (!ptl)
1701 return 0;
1703 * For architectures like ppc64 we look at deposited pgtable
1704 * when calling pmdp_huge_get_and_clear. So do the
1705 * pgtable_trans_huge_withdraw after finishing pmdp related
1706 * operations.
1708 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1709 tlb->fullmm);
1710 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1711 if (vma_is_dax(vma)) {
1712 if (arch_needs_pgtable_deposit())
1713 zap_deposited_table(tlb->mm, pmd);
1714 spin_unlock(ptl);
1715 if (is_huge_zero_pmd(orig_pmd))
1716 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1717 } else if (is_huge_zero_pmd(orig_pmd)) {
1718 zap_deposited_table(tlb->mm, pmd);
1719 spin_unlock(ptl);
1720 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1721 } else {
1722 struct page *page = NULL;
1723 int flush_needed = 1;
1725 if (pmd_present(orig_pmd)) {
1726 page = pmd_page(orig_pmd);
1727 page_remove_rmap(page, true);
1728 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1729 VM_BUG_ON_PAGE(!PageHead(page), page);
1730 } else if (thp_migration_supported()) {
1731 swp_entry_t entry;
1733 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1734 entry = pmd_to_swp_entry(orig_pmd);
1735 page = pfn_to_page(swp_offset(entry));
1736 flush_needed = 0;
1737 } else
1738 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1740 if (PageAnon(page)) {
1741 zap_deposited_table(tlb->mm, pmd);
1742 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1743 } else {
1744 if (arch_needs_pgtable_deposit())
1745 zap_deposited_table(tlb->mm, pmd);
1746 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1749 spin_unlock(ptl);
1750 if (flush_needed)
1751 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1753 return 1;
1756 #ifndef pmd_move_must_withdraw
1757 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1758 spinlock_t *old_pmd_ptl,
1759 struct vm_area_struct *vma)
1762 * With split pmd lock we also need to move preallocated
1763 * PTE page table if new_pmd is on different PMD page table.
1765 * We also don't deposit and withdraw tables for file pages.
1767 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1769 #endif
1771 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1773 #ifdef CONFIG_MEM_SOFT_DIRTY
1774 if (unlikely(is_pmd_migration_entry(pmd)))
1775 pmd = pmd_swp_mksoft_dirty(pmd);
1776 else if (pmd_present(pmd))
1777 pmd = pmd_mksoft_dirty(pmd);
1778 #endif
1779 return pmd;
1782 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1783 unsigned long new_addr, unsigned long old_end,
1784 pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1786 spinlock_t *old_ptl, *new_ptl;
1787 pmd_t pmd;
1788 struct mm_struct *mm = vma->vm_mm;
1789 bool force_flush = false;
1791 if ((old_addr & ~HPAGE_PMD_MASK) ||
1792 (new_addr & ~HPAGE_PMD_MASK) ||
1793 old_end - old_addr < HPAGE_PMD_SIZE)
1794 return false;
1797 * The destination pmd shouldn't be established, free_pgtables()
1798 * should have release it.
1800 if (WARN_ON(!pmd_none(*new_pmd))) {
1801 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1802 return false;
1806 * We don't have to worry about the ordering of src and dst
1807 * ptlocks because exclusive mmap_sem prevents deadlock.
1809 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1810 if (old_ptl) {
1811 new_ptl = pmd_lockptr(mm, new_pmd);
1812 if (new_ptl != old_ptl)
1813 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1814 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1815 if (pmd_present(pmd) && pmd_dirty(pmd))
1816 force_flush = true;
1817 VM_BUG_ON(!pmd_none(*new_pmd));
1819 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1820 pgtable_t pgtable;
1821 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1822 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1824 pmd = move_soft_dirty_pmd(pmd);
1825 set_pmd_at(mm, new_addr, new_pmd, pmd);
1826 if (new_ptl != old_ptl)
1827 spin_unlock(new_ptl);
1828 if (force_flush)
1829 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1830 else
1831 *need_flush = true;
1832 spin_unlock(old_ptl);
1833 return true;
1835 return false;
1839 * Returns
1840 * - 0 if PMD could not be locked
1841 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1842 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1844 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1845 unsigned long addr, pgprot_t newprot, int prot_numa)
1847 struct mm_struct *mm = vma->vm_mm;
1848 spinlock_t *ptl;
1849 pmd_t entry;
1850 bool preserve_write;
1851 int ret;
1853 ptl = __pmd_trans_huge_lock(pmd, vma);
1854 if (!ptl)
1855 return 0;
1857 preserve_write = prot_numa && pmd_write(*pmd);
1858 ret = 1;
1860 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1861 if (is_swap_pmd(*pmd)) {
1862 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1864 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1865 if (is_write_migration_entry(entry)) {
1866 pmd_t newpmd;
1868 * A protection check is difficult so
1869 * just be safe and disable write
1871 make_migration_entry_read(&entry);
1872 newpmd = swp_entry_to_pmd(entry);
1873 if (pmd_swp_soft_dirty(*pmd))
1874 newpmd = pmd_swp_mksoft_dirty(newpmd);
1875 set_pmd_at(mm, addr, pmd, newpmd);
1877 goto unlock;
1879 #endif
1882 * Avoid trapping faults against the zero page. The read-only
1883 * data is likely to be read-cached on the local CPU and
1884 * local/remote hits to the zero page are not interesting.
1886 if (prot_numa && is_huge_zero_pmd(*pmd))
1887 goto unlock;
1889 if (prot_numa && pmd_protnone(*pmd))
1890 goto unlock;
1893 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1894 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1895 * which is also under down_read(mmap_sem):
1897 * CPU0: CPU1:
1898 * change_huge_pmd(prot_numa=1)
1899 * pmdp_huge_get_and_clear_notify()
1900 * madvise_dontneed()
1901 * zap_pmd_range()
1902 * pmd_trans_huge(*pmd) == 0 (without ptl)
1903 * // skip the pmd
1904 * set_pmd_at();
1905 * // pmd is re-established
1907 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1908 * which may break userspace.
1910 * pmdp_invalidate() is required to make sure we don't miss
1911 * dirty/young flags set by hardware.
1913 entry = *pmd;
1914 pmdp_invalidate(vma, addr, pmd);
1917 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1918 * corrupt them.
1920 if (pmd_dirty(*pmd))
1921 entry = pmd_mkdirty(entry);
1922 if (pmd_young(*pmd))
1923 entry = pmd_mkyoung(entry);
1925 entry = pmd_modify(entry, newprot);
1926 if (preserve_write)
1927 entry = pmd_mk_savedwrite(entry);
1928 ret = HPAGE_PMD_NR;
1929 set_pmd_at(mm, addr, pmd, entry);
1930 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1931 unlock:
1932 spin_unlock(ptl);
1933 return ret;
1937 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1939 * Note that if it returns page table lock pointer, this routine returns without
1940 * unlocking page table lock. So callers must unlock it.
1942 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1944 spinlock_t *ptl;
1945 ptl = pmd_lock(vma->vm_mm, pmd);
1946 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1947 pmd_devmap(*pmd)))
1948 return ptl;
1949 spin_unlock(ptl);
1950 return NULL;
1954 * Returns true if a given pud maps a thp, false otherwise.
1956 * Note that if it returns true, this routine returns without unlocking page
1957 * table lock. So callers must unlock it.
1959 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1961 spinlock_t *ptl;
1963 ptl = pud_lock(vma->vm_mm, pud);
1964 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1965 return ptl;
1966 spin_unlock(ptl);
1967 return NULL;
1970 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1971 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1972 pud_t *pud, unsigned long addr)
1974 pud_t orig_pud;
1975 spinlock_t *ptl;
1977 ptl = __pud_trans_huge_lock(pud, vma);
1978 if (!ptl)
1979 return 0;
1981 * For architectures like ppc64 we look at deposited pgtable
1982 * when calling pudp_huge_get_and_clear. So do the
1983 * pgtable_trans_huge_withdraw after finishing pudp related
1984 * operations.
1986 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1987 tlb->fullmm);
1988 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1989 if (vma_is_dax(vma)) {
1990 spin_unlock(ptl);
1991 /* No zero page support yet */
1992 } else {
1993 /* No support for anonymous PUD pages yet */
1994 BUG();
1996 return 1;
1999 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2000 unsigned long haddr)
2002 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2003 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2004 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2005 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2007 count_vm_event(THP_SPLIT_PUD);
2009 pudp_huge_clear_flush_notify(vma, haddr, pud);
2012 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2013 unsigned long address)
2015 spinlock_t *ptl;
2016 struct mm_struct *mm = vma->vm_mm;
2017 unsigned long haddr = address & HPAGE_PUD_MASK;
2019 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2020 ptl = pud_lock(mm, pud);
2021 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2022 goto out;
2023 __split_huge_pud_locked(vma, pud, haddr);
2025 out:
2026 spin_unlock(ptl);
2028 * No need to double call mmu_notifier->invalidate_range() callback as
2029 * the above pudp_huge_clear_flush_notify() did already call it.
2031 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2032 HPAGE_PUD_SIZE);
2034 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2036 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2037 unsigned long haddr, pmd_t *pmd)
2039 struct mm_struct *mm = vma->vm_mm;
2040 pgtable_t pgtable;
2041 pmd_t _pmd;
2042 int i;
2045 * Leave pmd empty until pte is filled note that it is fine to delay
2046 * notification until mmu_notifier_invalidate_range_end() as we are
2047 * replacing a zero pmd write protected page with a zero pte write
2048 * protected page.
2050 * See Documentation/vm/mmu_notifier.txt
2052 pmdp_huge_clear_flush(vma, haddr, pmd);
2054 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2055 pmd_populate(mm, &_pmd, pgtable);
2057 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2058 pte_t *pte, entry;
2059 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2060 entry = pte_mkspecial(entry);
2061 pte = pte_offset_map(&_pmd, haddr);
2062 VM_BUG_ON(!pte_none(*pte));
2063 set_pte_at(mm, haddr, pte, entry);
2064 pte_unmap(pte);
2066 smp_wmb(); /* make pte visible before pmd */
2067 pmd_populate(mm, pmd, pgtable);
2070 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2071 unsigned long haddr, bool freeze)
2073 struct mm_struct *mm = vma->vm_mm;
2074 struct page *page;
2075 pgtable_t pgtable;
2076 pmd_t _pmd;
2077 bool young, write, dirty, soft_dirty, pmd_migration = false;
2078 unsigned long addr;
2079 int i;
2081 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2082 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2083 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2084 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2085 && !pmd_devmap(*pmd));
2087 count_vm_event(THP_SPLIT_PMD);
2089 if (!vma_is_anonymous(vma)) {
2090 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2092 * We are going to unmap this huge page. So
2093 * just go ahead and zap it
2095 if (arch_needs_pgtable_deposit())
2096 zap_deposited_table(mm, pmd);
2097 if (vma_is_dax(vma))
2098 return;
2099 page = pmd_page(_pmd);
2100 if (!PageReferenced(page) && pmd_young(_pmd))
2101 SetPageReferenced(page);
2102 page_remove_rmap(page, true);
2103 put_page(page);
2104 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2105 return;
2106 } else if (is_huge_zero_pmd(*pmd)) {
2108 * FIXME: Do we want to invalidate secondary mmu by calling
2109 * mmu_notifier_invalidate_range() see comments below inside
2110 * __split_huge_pmd() ?
2112 * We are going from a zero huge page write protected to zero
2113 * small page also write protected so it does not seems useful
2114 * to invalidate secondary mmu at this time.
2116 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2119 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2120 pmd_migration = is_pmd_migration_entry(*pmd);
2121 if (pmd_migration) {
2122 swp_entry_t entry;
2124 entry = pmd_to_swp_entry(*pmd);
2125 page = pfn_to_page(swp_offset(entry));
2126 } else
2127 #endif
2128 page = pmd_page(*pmd);
2129 VM_BUG_ON_PAGE(!page_count(page), page);
2130 page_ref_add(page, HPAGE_PMD_NR - 1);
2131 write = pmd_write(*pmd);
2132 young = pmd_young(*pmd);
2133 dirty = pmd_dirty(*pmd);
2134 soft_dirty = pmd_soft_dirty(*pmd);
2136 pmdp_huge_split_prepare(vma, haddr, pmd);
2137 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2138 pmd_populate(mm, &_pmd, pgtable);
2140 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2141 pte_t entry, *pte;
2143 * Note that NUMA hinting access restrictions are not
2144 * transferred to avoid any possibility of altering
2145 * permissions across VMAs.
2147 if (freeze || pmd_migration) {
2148 swp_entry_t swp_entry;
2149 swp_entry = make_migration_entry(page + i, write);
2150 entry = swp_entry_to_pte(swp_entry);
2151 if (soft_dirty)
2152 entry = pte_swp_mksoft_dirty(entry);
2153 } else {
2154 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2155 entry = maybe_mkwrite(entry, vma);
2156 if (!write)
2157 entry = pte_wrprotect(entry);
2158 if (!young)
2159 entry = pte_mkold(entry);
2160 if (soft_dirty)
2161 entry = pte_mksoft_dirty(entry);
2163 if (dirty)
2164 SetPageDirty(page + i);
2165 pte = pte_offset_map(&_pmd, addr);
2166 BUG_ON(!pte_none(*pte));
2167 set_pte_at(mm, addr, pte, entry);
2168 atomic_inc(&page[i]._mapcount);
2169 pte_unmap(pte);
2173 * Set PG_double_map before dropping compound_mapcount to avoid
2174 * false-negative page_mapped().
2176 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2177 for (i = 0; i < HPAGE_PMD_NR; i++)
2178 atomic_inc(&page[i]._mapcount);
2181 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2182 /* Last compound_mapcount is gone. */
2183 __dec_node_page_state(page, NR_ANON_THPS);
2184 if (TestClearPageDoubleMap(page)) {
2185 /* No need in mapcount reference anymore */
2186 for (i = 0; i < HPAGE_PMD_NR; i++)
2187 atomic_dec(&page[i]._mapcount);
2191 smp_wmb(); /* make pte visible before pmd */
2193 * Up to this point the pmd is present and huge and userland has the
2194 * whole access to the hugepage during the split (which happens in
2195 * place). If we overwrite the pmd with the not-huge version pointing
2196 * to the pte here (which of course we could if all CPUs were bug
2197 * free), userland could trigger a small page size TLB miss on the
2198 * small sized TLB while the hugepage TLB entry is still established in
2199 * the huge TLB. Some CPU doesn't like that.
2200 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2201 * 383 on page 93. Intel should be safe but is also warns that it's
2202 * only safe if the permission and cache attributes of the two entries
2203 * loaded in the two TLB is identical (which should be the case here).
2204 * But it is generally safer to never allow small and huge TLB entries
2205 * for the same virtual address to be loaded simultaneously. So instead
2206 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2207 * current pmd notpresent (atomically because here the pmd_trans_huge
2208 * and pmd_trans_splitting must remain set at all times on the pmd
2209 * until the split is complete for this pmd), then we flush the SMP TLB
2210 * and finally we write the non-huge version of the pmd entry with
2211 * pmd_populate.
2213 pmdp_invalidate(vma, haddr, pmd);
2214 pmd_populate(mm, pmd, pgtable);
2216 if (freeze) {
2217 for (i = 0; i < HPAGE_PMD_NR; i++) {
2218 page_remove_rmap(page + i, false);
2219 put_page(page + i);
2224 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2225 unsigned long address, bool freeze, struct page *page)
2227 spinlock_t *ptl;
2228 struct mm_struct *mm = vma->vm_mm;
2229 unsigned long haddr = address & HPAGE_PMD_MASK;
2231 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2232 ptl = pmd_lock(mm, pmd);
2235 * If caller asks to setup a migration entries, we need a page to check
2236 * pmd against. Otherwise we can end up replacing wrong page.
2238 VM_BUG_ON(freeze && !page);
2239 if (page && page != pmd_page(*pmd))
2240 goto out;
2242 if (pmd_trans_huge(*pmd)) {
2243 page = pmd_page(*pmd);
2244 if (PageMlocked(page))
2245 clear_page_mlock(page);
2246 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2247 goto out;
2248 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2249 out:
2250 spin_unlock(ptl);
2252 * No need to double call mmu_notifier->invalidate_range() callback.
2253 * They are 3 cases to consider inside __split_huge_pmd_locked():
2254 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2255 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2256 * fault will trigger a flush_notify before pointing to a new page
2257 * (it is fine if the secondary mmu keeps pointing to the old zero
2258 * page in the meantime)
2259 * 3) Split a huge pmd into pte pointing to the same page. No need
2260 * to invalidate secondary tlb entry they are all still valid.
2261 * any further changes to individual pte will notify. So no need
2262 * to call mmu_notifier->invalidate_range()
2264 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2265 HPAGE_PMD_SIZE);
2268 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2269 bool freeze, struct page *page)
2271 pgd_t *pgd;
2272 p4d_t *p4d;
2273 pud_t *pud;
2274 pmd_t *pmd;
2276 pgd = pgd_offset(vma->vm_mm, address);
2277 if (!pgd_present(*pgd))
2278 return;
2280 p4d = p4d_offset(pgd, address);
2281 if (!p4d_present(*p4d))
2282 return;
2284 pud = pud_offset(p4d, address);
2285 if (!pud_present(*pud))
2286 return;
2288 pmd = pmd_offset(pud, address);
2290 __split_huge_pmd(vma, pmd, address, freeze, page);
2293 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2294 unsigned long start,
2295 unsigned long end,
2296 long adjust_next)
2299 * If the new start address isn't hpage aligned and it could
2300 * previously contain an hugepage: check if we need to split
2301 * an huge pmd.
2303 if (start & ~HPAGE_PMD_MASK &&
2304 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2305 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2306 split_huge_pmd_address(vma, start, false, NULL);
2309 * If the new end address isn't hpage aligned and it could
2310 * previously contain an hugepage: check if we need to split
2311 * an huge pmd.
2313 if (end & ~HPAGE_PMD_MASK &&
2314 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2315 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2316 split_huge_pmd_address(vma, end, false, NULL);
2319 * If we're also updating the vma->vm_next->vm_start, if the new
2320 * vm_next->vm_start isn't page aligned and it could previously
2321 * contain an hugepage: check if we need to split an huge pmd.
2323 if (adjust_next > 0) {
2324 struct vm_area_struct *next = vma->vm_next;
2325 unsigned long nstart = next->vm_start;
2326 nstart += adjust_next << PAGE_SHIFT;
2327 if (nstart & ~HPAGE_PMD_MASK &&
2328 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2329 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2330 split_huge_pmd_address(next, nstart, false, NULL);
2334 static void freeze_page(struct page *page)
2336 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2337 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2338 bool unmap_success;
2340 VM_BUG_ON_PAGE(!PageHead(page), page);
2342 if (PageAnon(page))
2343 ttu_flags |= TTU_SPLIT_FREEZE;
2345 unmap_success = try_to_unmap(page, ttu_flags);
2346 VM_BUG_ON_PAGE(!unmap_success, page);
2349 static void unfreeze_page(struct page *page)
2351 int i;
2352 if (PageTransHuge(page)) {
2353 remove_migration_ptes(page, page, true);
2354 } else {
2355 for (i = 0; i < HPAGE_PMD_NR; i++)
2356 remove_migration_ptes(page + i, page + i, true);
2360 static void __split_huge_page_tail(struct page *head, int tail,
2361 struct lruvec *lruvec, struct list_head *list)
2363 struct page *page_tail = head + tail;
2365 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2366 VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
2369 * tail_page->_refcount is zero and not changing from under us. But
2370 * get_page_unless_zero() may be running from under us on the
2371 * tail_page. If we used atomic_set() below instead of atomic_inc() or
2372 * atomic_add(), we would then run atomic_set() concurrently with
2373 * get_page_unless_zero(), and atomic_set() is implemented in C not
2374 * using locked ops. spin_unlock on x86 sometime uses locked ops
2375 * because of PPro errata 66, 92, so unless somebody can guarantee
2376 * atomic_set() here would be safe on all archs (and not only on x86),
2377 * it's safer to use atomic_inc()/atomic_add().
2379 if (PageAnon(head) && !PageSwapCache(head)) {
2380 page_ref_inc(page_tail);
2381 } else {
2382 /* Additional pin to radix tree */
2383 page_ref_add(page_tail, 2);
2386 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2387 page_tail->flags |= (head->flags &
2388 ((1L << PG_referenced) |
2389 (1L << PG_swapbacked) |
2390 (1L << PG_swapcache) |
2391 (1L << PG_mlocked) |
2392 (1L << PG_uptodate) |
2393 (1L << PG_active) |
2394 (1L << PG_locked) |
2395 (1L << PG_unevictable) |
2396 (1L << PG_dirty)));
2399 * After clearing PageTail the gup refcount can be released.
2400 * Page flags also must be visible before we make the page non-compound.
2402 smp_wmb();
2404 clear_compound_head(page_tail);
2406 if (page_is_young(head))
2407 set_page_young(page_tail);
2408 if (page_is_idle(head))
2409 set_page_idle(page_tail);
2411 /* ->mapping in first tail page is compound_mapcount */
2412 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2413 page_tail);
2414 page_tail->mapping = head->mapping;
2416 page_tail->index = head->index + tail;
2417 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2418 lru_add_page_tail(head, page_tail, lruvec, list);
2421 static void __split_huge_page(struct page *page, struct list_head *list,
2422 unsigned long flags)
2424 struct page *head = compound_head(page);
2425 struct zone *zone = page_zone(head);
2426 struct lruvec *lruvec;
2427 pgoff_t end = -1;
2428 int i;
2430 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2432 /* complete memcg works before add pages to LRU */
2433 mem_cgroup_split_huge_fixup(head);
2435 if (!PageAnon(page))
2436 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2438 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2439 __split_huge_page_tail(head, i, lruvec, list);
2440 /* Some pages can be beyond i_size: drop them from page cache */
2441 if (head[i].index >= end) {
2442 __ClearPageDirty(head + i);
2443 __delete_from_page_cache(head + i, NULL);
2444 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2445 shmem_uncharge(head->mapping->host, 1);
2446 put_page(head + i);
2450 ClearPageCompound(head);
2451 /* See comment in __split_huge_page_tail() */
2452 if (PageAnon(head)) {
2453 /* Additional pin to radix tree of swap cache */
2454 if (PageSwapCache(head))
2455 page_ref_add(head, 2);
2456 else
2457 page_ref_inc(head);
2458 } else {
2459 /* Additional pin to radix tree */
2460 page_ref_add(head, 2);
2461 spin_unlock(&head->mapping->tree_lock);
2464 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2466 unfreeze_page(head);
2468 for (i = 0; i < HPAGE_PMD_NR; i++) {
2469 struct page *subpage = head + i;
2470 if (subpage == page)
2471 continue;
2472 unlock_page(subpage);
2475 * Subpages may be freed if there wasn't any mapping
2476 * like if add_to_swap() is running on a lru page that
2477 * had its mapping zapped. And freeing these pages
2478 * requires taking the lru_lock so we do the put_page
2479 * of the tail pages after the split is complete.
2481 put_page(subpage);
2485 int total_mapcount(struct page *page)
2487 int i, compound, ret;
2489 VM_BUG_ON_PAGE(PageTail(page), page);
2491 if (likely(!PageCompound(page)))
2492 return atomic_read(&page->_mapcount) + 1;
2494 compound = compound_mapcount(page);
2495 if (PageHuge(page))
2496 return compound;
2497 ret = compound;
2498 for (i = 0; i < HPAGE_PMD_NR; i++)
2499 ret += atomic_read(&page[i]._mapcount) + 1;
2500 /* File pages has compound_mapcount included in _mapcount */
2501 if (!PageAnon(page))
2502 return ret - compound * HPAGE_PMD_NR;
2503 if (PageDoubleMap(page))
2504 ret -= HPAGE_PMD_NR;
2505 return ret;
2509 * This calculates accurately how many mappings a transparent hugepage
2510 * has (unlike page_mapcount() which isn't fully accurate). This full
2511 * accuracy is primarily needed to know if copy-on-write faults can
2512 * reuse the page and change the mapping to read-write instead of
2513 * copying them. At the same time this returns the total_mapcount too.
2515 * The function returns the highest mapcount any one of the subpages
2516 * has. If the return value is one, even if different processes are
2517 * mapping different subpages of the transparent hugepage, they can
2518 * all reuse it, because each process is reusing a different subpage.
2520 * The total_mapcount is instead counting all virtual mappings of the
2521 * subpages. If the total_mapcount is equal to "one", it tells the
2522 * caller all mappings belong to the same "mm" and in turn the
2523 * anon_vma of the transparent hugepage can become the vma->anon_vma
2524 * local one as no other process may be mapping any of the subpages.
2526 * It would be more accurate to replace page_mapcount() with
2527 * page_trans_huge_mapcount(), however we only use
2528 * page_trans_huge_mapcount() in the copy-on-write faults where we
2529 * need full accuracy to avoid breaking page pinning, because
2530 * page_trans_huge_mapcount() is slower than page_mapcount().
2532 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2534 int i, ret, _total_mapcount, mapcount;
2536 /* hugetlbfs shouldn't call it */
2537 VM_BUG_ON_PAGE(PageHuge(page), page);
2539 if (likely(!PageTransCompound(page))) {
2540 mapcount = atomic_read(&page->_mapcount) + 1;
2541 if (total_mapcount)
2542 *total_mapcount = mapcount;
2543 return mapcount;
2546 page = compound_head(page);
2548 _total_mapcount = ret = 0;
2549 for (i = 0; i < HPAGE_PMD_NR; i++) {
2550 mapcount = atomic_read(&page[i]._mapcount) + 1;
2551 ret = max(ret, mapcount);
2552 _total_mapcount += mapcount;
2554 if (PageDoubleMap(page)) {
2555 ret -= 1;
2556 _total_mapcount -= HPAGE_PMD_NR;
2558 mapcount = compound_mapcount(page);
2559 ret += mapcount;
2560 _total_mapcount += mapcount;
2561 if (total_mapcount)
2562 *total_mapcount = _total_mapcount;
2563 return ret;
2566 /* Racy check whether the huge page can be split */
2567 bool can_split_huge_page(struct page *page, int *pextra_pins)
2569 int extra_pins;
2571 /* Additional pins from radix tree */
2572 if (PageAnon(page))
2573 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2574 else
2575 extra_pins = HPAGE_PMD_NR;
2576 if (pextra_pins)
2577 *pextra_pins = extra_pins;
2578 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2582 * This function splits huge page into normal pages. @page can point to any
2583 * subpage of huge page to split. Split doesn't change the position of @page.
2585 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2586 * The huge page must be locked.
2588 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2590 * Both head page and tail pages will inherit mapping, flags, and so on from
2591 * the hugepage.
2593 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2594 * they are not mapped.
2596 * Returns 0 if the hugepage is split successfully.
2597 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2598 * us.
2600 int split_huge_page_to_list(struct page *page, struct list_head *list)
2602 struct page *head = compound_head(page);
2603 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2604 struct anon_vma *anon_vma = NULL;
2605 struct address_space *mapping = NULL;
2606 int count, mapcount, extra_pins, ret;
2607 bool mlocked;
2608 unsigned long flags;
2610 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2611 VM_BUG_ON_PAGE(!PageLocked(page), page);
2612 VM_BUG_ON_PAGE(!PageCompound(page), page);
2614 if (PageWriteback(page))
2615 return -EBUSY;
2617 if (PageAnon(head)) {
2619 * The caller does not necessarily hold an mmap_sem that would
2620 * prevent the anon_vma disappearing so we first we take a
2621 * reference to it and then lock the anon_vma for write. This
2622 * is similar to page_lock_anon_vma_read except the write lock
2623 * is taken to serialise against parallel split or collapse
2624 * operations.
2626 anon_vma = page_get_anon_vma(head);
2627 if (!anon_vma) {
2628 ret = -EBUSY;
2629 goto out;
2631 mapping = NULL;
2632 anon_vma_lock_write(anon_vma);
2633 } else {
2634 mapping = head->mapping;
2636 /* Truncated ? */
2637 if (!mapping) {
2638 ret = -EBUSY;
2639 goto out;
2642 anon_vma = NULL;
2643 i_mmap_lock_read(mapping);
2647 * Racy check if we can split the page, before freeze_page() will
2648 * split PMDs
2650 if (!can_split_huge_page(head, &extra_pins)) {
2651 ret = -EBUSY;
2652 goto out_unlock;
2655 mlocked = PageMlocked(page);
2656 freeze_page(head);
2657 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2659 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2660 if (mlocked)
2661 lru_add_drain();
2663 /* prevent PageLRU to go away from under us, and freeze lru stats */
2664 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2666 if (mapping) {
2667 void **pslot;
2669 spin_lock(&mapping->tree_lock);
2670 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2671 page_index(head));
2673 * Check if the head page is present in radix tree.
2674 * We assume all tail are present too, if head is there.
2676 if (radix_tree_deref_slot_protected(pslot,
2677 &mapping->tree_lock) != head)
2678 goto fail;
2681 /* Prevent deferred_split_scan() touching ->_refcount */
2682 spin_lock(&pgdata->split_queue_lock);
2683 count = page_count(head);
2684 mapcount = total_mapcount(head);
2685 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2686 if (!list_empty(page_deferred_list(head))) {
2687 pgdata->split_queue_len--;
2688 list_del(page_deferred_list(head));
2690 if (mapping)
2691 __dec_node_page_state(page, NR_SHMEM_THPS);
2692 spin_unlock(&pgdata->split_queue_lock);
2693 __split_huge_page(page, list, flags);
2694 if (PageSwapCache(head)) {
2695 swp_entry_t entry = { .val = page_private(head) };
2697 ret = split_swap_cluster(entry);
2698 } else
2699 ret = 0;
2700 } else {
2701 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2702 pr_alert("total_mapcount: %u, page_count(): %u\n",
2703 mapcount, count);
2704 if (PageTail(page))
2705 dump_page(head, NULL);
2706 dump_page(page, "total_mapcount(head) > 0");
2707 BUG();
2709 spin_unlock(&pgdata->split_queue_lock);
2710 fail: if (mapping)
2711 spin_unlock(&mapping->tree_lock);
2712 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2713 unfreeze_page(head);
2714 ret = -EBUSY;
2717 out_unlock:
2718 if (anon_vma) {
2719 anon_vma_unlock_write(anon_vma);
2720 put_anon_vma(anon_vma);
2722 if (mapping)
2723 i_mmap_unlock_read(mapping);
2724 out:
2725 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2726 return ret;
2729 void free_transhuge_page(struct page *page)
2731 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2732 unsigned long flags;
2734 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2735 if (!list_empty(page_deferred_list(page))) {
2736 pgdata->split_queue_len--;
2737 list_del(page_deferred_list(page));
2739 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2740 free_compound_page(page);
2743 void deferred_split_huge_page(struct page *page)
2745 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2746 unsigned long flags;
2748 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2750 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2751 if (list_empty(page_deferred_list(page))) {
2752 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2753 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2754 pgdata->split_queue_len++;
2756 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2759 static unsigned long deferred_split_count(struct shrinker *shrink,
2760 struct shrink_control *sc)
2762 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2763 return READ_ONCE(pgdata->split_queue_len);
2766 static unsigned long deferred_split_scan(struct shrinker *shrink,
2767 struct shrink_control *sc)
2769 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2770 unsigned long flags;
2771 LIST_HEAD(list), *pos, *next;
2772 struct page *page;
2773 int split = 0;
2775 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2776 /* Take pin on all head pages to avoid freeing them under us */
2777 list_for_each_safe(pos, next, &pgdata->split_queue) {
2778 page = list_entry((void *)pos, struct page, mapping);
2779 page = compound_head(page);
2780 if (get_page_unless_zero(page)) {
2781 list_move(page_deferred_list(page), &list);
2782 } else {
2783 /* We lost race with put_compound_page() */
2784 list_del_init(page_deferred_list(page));
2785 pgdata->split_queue_len--;
2787 if (!--sc->nr_to_scan)
2788 break;
2790 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2792 list_for_each_safe(pos, next, &list) {
2793 page = list_entry((void *)pos, struct page, mapping);
2794 lock_page(page);
2795 /* split_huge_page() removes page from list on success */
2796 if (!split_huge_page(page))
2797 split++;
2798 unlock_page(page);
2799 put_page(page);
2802 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2803 list_splice_tail(&list, &pgdata->split_queue);
2804 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2807 * Stop shrinker if we didn't split any page, but the queue is empty.
2808 * This can happen if pages were freed under us.
2810 if (!split && list_empty(&pgdata->split_queue))
2811 return SHRINK_STOP;
2812 return split;
2815 static struct shrinker deferred_split_shrinker = {
2816 .count_objects = deferred_split_count,
2817 .scan_objects = deferred_split_scan,
2818 .seeks = DEFAULT_SEEKS,
2819 .flags = SHRINKER_NUMA_AWARE,
2822 #ifdef CONFIG_DEBUG_FS
2823 static int split_huge_pages_set(void *data, u64 val)
2825 struct zone *zone;
2826 struct page *page;
2827 unsigned long pfn, max_zone_pfn;
2828 unsigned long total = 0, split = 0;
2830 if (val != 1)
2831 return -EINVAL;
2833 for_each_populated_zone(zone) {
2834 max_zone_pfn = zone_end_pfn(zone);
2835 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2836 if (!pfn_valid(pfn))
2837 continue;
2839 page = pfn_to_page(pfn);
2840 if (!get_page_unless_zero(page))
2841 continue;
2843 if (zone != page_zone(page))
2844 goto next;
2846 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2847 goto next;
2849 total++;
2850 lock_page(page);
2851 if (!split_huge_page(page))
2852 split++;
2853 unlock_page(page);
2854 next:
2855 put_page(page);
2859 pr_info("%lu of %lu THP split\n", split, total);
2861 return 0;
2863 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2864 "%llu\n");
2866 static int __init split_huge_pages_debugfs(void)
2868 void *ret;
2870 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2871 &split_huge_pages_fops);
2872 if (!ret)
2873 pr_warn("Failed to create split_huge_pages in debugfs");
2874 return 0;
2876 late_initcall(split_huge_pages_debugfs);
2877 #endif
2879 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2880 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2881 struct page *page)
2883 struct vm_area_struct *vma = pvmw->vma;
2884 struct mm_struct *mm = vma->vm_mm;
2885 unsigned long address = pvmw->address;
2886 pmd_t pmdval;
2887 swp_entry_t entry;
2888 pmd_t pmdswp;
2890 if (!(pvmw->pmd && !pvmw->pte))
2891 return;
2893 mmu_notifier_invalidate_range_start(mm, address,
2894 address + HPAGE_PMD_SIZE);
2896 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2897 pmdval = *pvmw->pmd;
2898 pmdp_invalidate(vma, address, pvmw->pmd);
2899 if (pmd_dirty(pmdval))
2900 set_page_dirty(page);
2901 entry = make_migration_entry(page, pmd_write(pmdval));
2902 pmdswp = swp_entry_to_pmd(entry);
2903 if (pmd_soft_dirty(pmdval))
2904 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2905 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2906 page_remove_rmap(page, true);
2907 put_page(page);
2909 mmu_notifier_invalidate_range_end(mm, address,
2910 address + HPAGE_PMD_SIZE);
2913 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2915 struct vm_area_struct *vma = pvmw->vma;
2916 struct mm_struct *mm = vma->vm_mm;
2917 unsigned long address = pvmw->address;
2918 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2919 pmd_t pmde;
2920 swp_entry_t entry;
2922 if (!(pvmw->pmd && !pvmw->pte))
2923 return;
2925 entry = pmd_to_swp_entry(*pvmw->pmd);
2926 get_page(new);
2927 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2928 if (pmd_swp_soft_dirty(*pvmw->pmd))
2929 pmde = pmd_mksoft_dirty(pmde);
2930 if (is_write_migration_entry(entry))
2931 pmde = maybe_pmd_mkwrite(pmde, vma);
2933 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2934 page_add_anon_rmap(new, vma, mmun_start, true);
2935 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2936 if (vma->vm_flags & VM_LOCKED)
2937 mlock_vma_page(new);
2938 update_mmu_cache_pmd(vma, address, pvmw->pmd);
2940 #endif