diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 5148 |
1 files changed, 5148 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c new file mode 100644 index 000000000..644d6905b --- /dev/null +++ b/mm/huge_memory.c @@ -0,0 +1,5148 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2009 Red Hat, Inc. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/sched/mm.h> +#include <linux/sched/numa_balancing.h> +#include <linux/highmem.h> +#include <linux/hugetlb.h> +#include <linux/mmu_notifier.h> +#include <linux/rmap.h> +#include <linux/swap.h> +#include <linux/list_lru.h> +#include <linux/shrinker.h> +#include <linux/mm_inline.h> +#include <linux/swapops.h> +#include <linux/backing-dev.h> +#include <linux/dax.h> +#include <linux/mm_types.h> +#include <linux/khugepaged.h> +#include <linux/freezer.h> +#include <linux/mman.h> +#include <linux/memremap.h> +#include <linux/pagemap.h> +#include <linux/debugfs.h> +#include <linux/migrate.h> +#include <linux/hashtable.h> +#include <linux/userfaultfd_k.h> +#include <linux/page_idle.h> +#include <linux/shmem_fs.h> +#include <linux/oom.h> +#include <linux/numa.h> +#include <linux/page_owner.h> +#include <linux/sched/sysctl.h> +#include <linux/memory-tiers.h> +#include <linux/compat.h> +#include <linux/pgalloc.h> +#include <linux/pgalloc_tag.h> +#include <linux/pagewalk.h> +#include <linux/cleanup.h> + +#include <asm/tlb.h> +#include "internal.h" +#include "swap.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/thp.h> + +/* + * By default, transparent hugepage support is disabled in order to avoid + * risking an increased memory footprint for applications that are not + * guaranteed to benefit from it. When transparent hugepage support is + * enabled, it is for all mappings, and khugepaged scans all mappings. + * Defrag is invoked by khugepaged hugepage allocations and by page faults + * for all hugepage allocations. + */ +unsigned long transparent_hugepage_flags __read_mostly = +#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS + (1<<TRANSPARENT_HUGEPAGE_FLAG)| +#endif +#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE + (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| +#endif + (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| + (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| + (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); + +static struct lock_class_key deferred_split_key; +static struct list_lru deferred_split_lru; +static struct shrinker *deferred_split_shrinker; +static unsigned long deferred_split_count(struct shrinker *shrink, + struct shrink_control *sc); +static unsigned long deferred_split_scan(struct shrinker *shrink, + struct shrink_control *sc); +static bool split_underused_thp = true; + +#define HUGE_ZERO_UNSET_PFN (~0UL) +struct folio *huge_zero_folio __read_mostly; +unsigned long huge_zero_pfn __read_mostly = HUGE_ZERO_UNSET_PFN; +#ifndef CONFIG_PERSISTENT_HUGE_ZERO_FOLIO +static atomic_t huge_zero_refcount; +static DEFINE_SPINLOCK(huge_zero_lock); +static struct shrinker *huge_zero_folio_shrinker; +#endif + +unsigned long huge_anon_orders_always __read_mostly; +unsigned long huge_anon_orders_madvise __read_mostly; +unsigned long huge_anon_orders_inherit __read_mostly; +static bool anon_orders_configured __initdata; + +static inline bool file_thp_enabled(struct vm_area_struct *vma) +{ + struct inode *inode; + + if (!vma->vm_file) + return false; + + inode = file_inode(vma->vm_file); + + if (IS_ANON_FILE(inode)) + return false; + + if (!mapping_pmd_folio_support(vma->vm_file->f_mapping)) + return false; + + return S_ISREG(inode->i_mode); +} + +/* If returns true, we are unable to access the VMA's folios. */ +static bool vma_is_special_huge(const struct vm_area_struct *vma) +{ + if (vma_is_dax(vma)) + return false; + return vma_test_any(vma, VMA_PFNMAP_BIT, VMA_MIXEDMAP_BIT); +} + +unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, + vm_flags_t vm_flags, + enum tva_type type, + unsigned long orders) +{ + const bool smaps = type == TVA_SMAPS; + const bool in_pf = type == TVA_PAGEFAULT; + const bool forced_collapse = type == TVA_FORCED_COLLAPSE; + unsigned long supported_orders; + + /* Check the intersection of requested and supported orders. */ + if (vma_is_anonymous(vma)) + supported_orders = THP_ORDERS_ALL_ANON; + else if (vma_is_dax(vma) || vma_is_special_huge(vma)) + supported_orders = THP_ORDERS_ALL_SPECIAL_DAX; + else + supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; + + orders &= supported_orders; + if (!orders) + return 0; + + if (!vma->vm_mm) /* vdso */ + return 0; + + if (thp_disabled_by_hw() || vma_thp_disabled(vma, vm_flags, forced_collapse)) + return 0; + + /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ + if (vma_is_dax(vma)) + return in_pf ? orders : 0; + + /* + * khugepaged special VMA and hugetlb VMA. + * Must be checked after dax since some dax mappings may have + * VM_MIXEDMAP set. + */ + if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) + return 0; + + /* + * Check alignment for file vma and size for both file and anon vma by + * filtering out the unsuitable orders. + * + * Skip the check for page fault. Huge fault does the check in fault + * handlers. + */ + if (!in_pf) { + int order = highest_order(orders); + unsigned long addr; + + while (orders) { + addr = vma->vm_end - (PAGE_SIZE << order); + if (thp_vma_suitable_order(vma, addr, order)) + break; + order = next_order(&orders, order); + } + + if (!orders) + return 0; + } + + /* + * Enabled via shmem mount options or sysfs settings. + * Must be done before hugepage flags check since shmem has its + * own flags. + */ + if (!in_pf && shmem_file(vma->vm_file)) + return orders & shmem_allowable_huge_orders(file_inode(vma->vm_file), + vma, vma_start_pgoff(vma), 0, + forced_collapse); + + if (!vma_is_anonymous(vma)) { + /* + * Enforce THP collapse requirements as necessary. Anonymous vmas + * were already handled in thp_vma_allowable_orders(). + */ + if (!forced_collapse && + (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) && + !hugepage_global_always()))) + return 0; + + /* + * Trust that ->huge_fault() handlers know what they are doing + * in fault path. + */ + if (((in_pf || smaps)) && vma->vm_ops->huge_fault) + return orders; + /* Only regular file is valid in collapse path */ + if (((!in_pf || smaps)) && file_thp_enabled(vma)) + return orders; + return 0; + } + + if (vma_is_temporary_stack(vma)) + return 0; + + /* + * THPeligible bit of smaps should show 1 for proper VMAs even + * though anon_vma is not initialized yet. + * + * Allow page fault since anon_vma may be not initialized until + * the first page fault. + */ + if (!vma->anon_vma) + return (smaps || in_pf) ? orders : 0; + + return orders; +} + +static struct folio *alloc_huge_zero_folio(void) +{ + struct folio *zero_folio; + + zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO | __GFP_ZEROTAGS) & + ~__GFP_MOVABLE, + HPAGE_PMD_ORDER); + if (!zero_folio) { + count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); + return NULL; + } + folio_clear_large_rmappable(zero_folio); /* Explicitly not rmappable. */ + return zero_folio; +} + +#ifdef CONFIG_PERSISTENT_HUGE_ZERO_FOLIO +static int __init huge_zero_init(void) +{ + huge_zero_folio = alloc_huge_zero_folio(); + if (!huge_zero_folio) { + pr_warn("Allocating persistent huge zero folio failed\n"); + } else { + huge_zero_pfn = folio_pfn(huge_zero_folio); + count_vm_event(THP_ZERO_PAGE_ALLOC); + } + return 0; +} + +static void __init huge_zero_shrinker_exit(void) +{ +} + +struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) +{ + return huge_zero_folio; +} + +void mm_put_huge_zero_folio(struct mm_struct *mm) +{ +} +#else +static bool get_huge_zero_folio(void) +{ + struct folio *zero_folio; + + /* Paired with atomic_set_release(). */ + if (likely(atomic_inc_not_zero(&huge_zero_refcount))) + return true; + + zero_folio = alloc_huge_zero_folio(); + if (unlikely(!zero_folio)) + return false; + + /* Paired with critical section in shrink_huge_zero_folio_scan(). */ + spin_lock(&huge_zero_lock); + if (huge_zero_folio) { + /* Somebody else already installed it. */ + atomic_inc(&huge_zero_refcount); + spin_unlock(&huge_zero_lock); + folio_put(zero_folio); + return true; + } + WRITE_ONCE(huge_zero_folio, zero_folio); + WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); + /* Paired with atomic_inc_not_zero(). +1 for shrinker pin. */ + atomic_set_release(&huge_zero_refcount, 2); + spin_unlock(&huge_zero_lock); + + count_vm_event(THP_ZERO_PAGE_ALLOC); + return true; +} + +static void put_huge_zero_folio(void) +{ + /* + * Counter should never go to zero here. Only shrinker can put + * last reference. + */ + WARN_ON_ONCE(atomic_dec_and_test(&huge_zero_refcount)); +} + +static unsigned long shrink_huge_zero_folio_count(struct shrinker *shrink, + struct shrink_control *sc) +{ + /* we can free zero page only if last reference remains */ + return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; +} + +static unsigned long shrink_huge_zero_folio_scan(struct shrinker *shrink, + struct shrink_control *sc) +{ + struct folio *zero_folio; + + /* Paired with critical section in get_huge_zero_folio(). */ + scoped_guard(spinlock, &huge_zero_lock) { + /* Paired with atomic_inc_not_zero() in get_huge_zero_folio(). */ + if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) != 1) + return 0; + + zero_folio = huge_zero_folio; + VM_WARN_ON_ONCE(!zero_folio); + WRITE_ONCE(huge_zero_folio, NULL); + WRITE_ONCE(huge_zero_pfn, HUGE_ZERO_UNSET_PFN); + } + + folio_put(zero_folio); + return HPAGE_PMD_NR; +} + +static int __init huge_zero_init(void) +{ + huge_zero_folio_shrinker = shrinker_alloc(0, "thp-zero"); + if (!huge_zero_folio_shrinker) { + shrinker_free(deferred_split_shrinker); + list_lru_destroy(&deferred_split_lru); + return -ENOMEM; + } + + huge_zero_folio_shrinker->count_objects = shrink_huge_zero_folio_count; + huge_zero_folio_shrinker->scan_objects = shrink_huge_zero_folio_scan; + shrinker_register(huge_zero_folio_shrinker); + return 0; +} + +static void __init huge_zero_shrinker_exit(void) +{ + shrinker_free(huge_zero_folio_shrinker); +} + +struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) +{ + if (mm_flags_test(MMF_HUGE_ZERO_FOLIO, mm)) + return READ_ONCE(huge_zero_folio); + + if (!get_huge_zero_folio()) + return NULL; + + if (mm_flags_test_and_set(MMF_HUGE_ZERO_FOLIO, mm)) + put_huge_zero_folio(); + + return READ_ONCE(huge_zero_folio); +} + +void mm_put_huge_zero_folio(struct mm_struct *mm) +{ + if (mm_flags_test(MMF_HUGE_ZERO_FOLIO, mm)) + put_huge_zero_folio(); +} +#endif /* CONFIG_PERSISTENT_HUGE_ZERO_FOLIO */ + +#ifdef CONFIG_SYSFS +static ssize_t enabled_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + const char *output; + + if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) + output = "[always] madvise never"; + else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + &transparent_hugepage_flags)) + output = "always [madvise] never"; + else + output = "always madvise [never]"; + + return sysfs_emit(buf, "%s\n", output); +} + +enum anon_enabled_mode { + ANON_ENABLED_ALWAYS = 0, + ANON_ENABLED_INHERIT = 1, + ANON_ENABLED_MADVISE = 2, + ANON_ENABLED_NEVER = 3, +}; + +static const char * const anon_enabled_mode_strings[] = { + [ANON_ENABLED_ALWAYS] = "always", + [ANON_ENABLED_INHERIT] = "inherit", + [ANON_ENABLED_MADVISE] = "madvise", + [ANON_ENABLED_NEVER] = "never", +}; + +enum global_enabled_mode { + GLOBAL_ENABLED_ALWAYS = 0, + GLOBAL_ENABLED_MADVISE = 1, + GLOBAL_ENABLED_NEVER = 2, +}; + +static const char * const global_enabled_mode_strings[] = { + [GLOBAL_ENABLED_ALWAYS] = "always", + [GLOBAL_ENABLED_MADVISE] = "madvise", + [GLOBAL_ENABLED_NEVER] = "never", +}; + +static bool set_global_enabled_mode(enum global_enabled_mode mode) +{ + static const unsigned long thp_flags[] = { + TRANSPARENT_HUGEPAGE_FLAG, + TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + }; + enum global_enabled_mode m; + bool changed = false; + + for (m = 0; m < ARRAY_SIZE(thp_flags); m++) { + if (m == mode) + changed |= !test_and_set_bit(thp_flags[m], + &transparent_hugepage_flags); + else + changed |= test_and_clear_bit(thp_flags[m], + &transparent_hugepage_flags); + } + + return changed; +} + +static ssize_t enabled_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int mode; + + mode = sysfs_match_string(global_enabled_mode_strings, buf); + if (mode < 0) + return -EINVAL; + + if (set_global_enabled_mode(mode)) { + int err = start_stop_khugepaged(); + + if (err) + return err; + } else { + /* + * Recalculate watermarks even when the mode didn't + * change, as the previous code always called + * start_stop_khugepaged() which does this internally. + */ + set_recommended_min_free_kbytes(); + } + return count; +} + +static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); + +ssize_t single_hugepage_flag_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf, + enum transparent_hugepage_flag flag) +{ + return sysfs_emit(buf, "%d\n", + !!test_bit(flag, &transparent_hugepage_flags)); +} + +ssize_t single_hugepage_flag_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count, + enum transparent_hugepage_flag flag) +{ + unsigned long value; + int ret; + + ret = kstrtoul(buf, 10, &value); + if (ret < 0) + return ret; + if (value > 1) + return -EINVAL; + + if (value) + set_bit(flag, &transparent_hugepage_flags); + else + clear_bit(flag, &transparent_hugepage_flags); + + return count; +} + +enum defrag_mode { + DEFRAG_ALWAYS = 0, + DEFRAG_DEFER, + DEFRAG_DEFER_MADVISE, + DEFRAG_MADVISE, + DEFRAG_NEVER, +}; + +static const char * const defrag_mode_strings[] = { + [DEFRAG_ALWAYS] = "always", + [DEFRAG_DEFER] = "defer", + [DEFRAG_DEFER_MADVISE] = "defer+madvise", + [DEFRAG_MADVISE] = "madvise", + [DEFRAG_NEVER] = "never", +}; + +static const enum transparent_hugepage_flag defrag_flags[] = { + [DEFRAG_ALWAYS] = TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, + [DEFRAG_DEFER] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, + [DEFRAG_DEFER_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, + [DEFRAG_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, +}; + +static ssize_t defrag_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + int active = DEFRAG_NEVER; + int len = 0; + int i; + + for (i = 0; i < ARRAY_SIZE(defrag_flags); i++) { + if (test_bit(defrag_flags[i], &transparent_hugepage_flags)) { + active = i; + break; + } + } + + for (i = 0; i < ARRAY_SIZE(defrag_mode_strings); i++) { + if (i == active) + len += sysfs_emit_at(buf, len, "[%s] ", + defrag_mode_strings[i]); + else + len += sysfs_emit_at(buf, len, "%s ", + defrag_mode_strings[i]); + } + + /* Replace trailing space with newline */ + buf[len - 1] = '\n'; + + return len; +} + +static ssize_t defrag_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int mode, m; + + mode = sysfs_match_string(defrag_mode_strings, buf); + if (mode < 0) + return -EINVAL; + + for (m = 0; m < ARRAY_SIZE(defrag_flags); m++) { + if (m == mode) + set_bit(defrag_flags[m], &transparent_hugepage_flags); + else + clear_bit(defrag_flags[m], &transparent_hugepage_flags); + } + + return count; +} +static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); + +static ssize_t use_zero_page_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return single_hugepage_flag_show(kobj, attr, buf, + TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); +} +static ssize_t use_zero_page_store(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + return single_hugepage_flag_store(kobj, attr, buf, count, + TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); +} +static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); + +static ssize_t hpage_pmd_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); +} +static struct kobj_attribute hpage_pmd_size_attr = + __ATTR_RO(hpage_pmd_size); + +static ssize_t split_underused_thp_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", split_underused_thp); +} + +static ssize_t split_underused_thp_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err = kstrtobool(buf, &split_underused_thp); + + if (err < 0) + return err; + + return count; +} + +static struct kobj_attribute split_underused_thp_attr = __ATTR( + shrink_underused, 0644, split_underused_thp_show, split_underused_thp_store); + +static struct attribute *hugepage_attr[] = { + &enabled_attr.attr, + &defrag_attr.attr, + &use_zero_page_attr.attr, + &hpage_pmd_size_attr.attr, +#ifdef CONFIG_SHMEM + &shmem_enabled_attr.attr, +#endif + &split_underused_thp_attr.attr, + NULL, +}; + +static const struct attribute_group hugepage_attr_group = { + .attrs = hugepage_attr, +}; + +static void hugepage_exit_sysfs(struct kobject *hugepage_kobj); +static void thpsize_release(struct kobject *kobj); +static DEFINE_SPINLOCK(huge_anon_orders_lock); +static LIST_HEAD(thpsize_list); + +static ssize_t anon_enabled_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + int order = to_thpsize(kobj)->order; + const char *output; + + if (test_bit(order, &huge_anon_orders_always)) + output = "[always] inherit madvise never"; + else if (test_bit(order, &huge_anon_orders_inherit)) + output = "always [inherit] madvise never"; + else if (test_bit(order, &huge_anon_orders_madvise)) + output = "always inherit [madvise] never"; + else + output = "always inherit madvise [never]"; + + return sysfs_emit(buf, "%s\n", output); +} + +static bool set_anon_enabled_mode(int order, enum anon_enabled_mode mode) +{ + static unsigned long *enabled_orders[] = { + &huge_anon_orders_always, + &huge_anon_orders_inherit, + &huge_anon_orders_madvise, + }; + enum anon_enabled_mode m; + bool changed = false; + + spin_lock(&huge_anon_orders_lock); + for (m = 0; m < ARRAY_SIZE(enabled_orders); m++) { + if (m == mode) + changed |= !__test_and_set_bit(order, enabled_orders[m]); + else + changed |= __test_and_clear_bit(order, enabled_orders[m]); + } + spin_unlock(&huge_anon_orders_lock); + + return changed; +} + +static ssize_t anon_enabled_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int order = to_thpsize(kobj)->order; + int mode; + + mode = sysfs_match_string(anon_enabled_mode_strings, buf); + if (mode < 0) + return -EINVAL; + + if (set_anon_enabled_mode(order, mode)) { + int err = start_stop_khugepaged(); + + if (err) + return err; + } else { + /* + * Recalculate watermarks even when the mode didn't + * change, as the previous code always called + * start_stop_khugepaged() which does this internally. + */ + set_recommended_min_free_kbytes(); + } + + return count; +} + +static struct kobj_attribute anon_enabled_attr = + __ATTR(enabled, 0644, anon_enabled_show, anon_enabled_store); + +static struct attribute *anon_ctrl_attrs[] = { + &anon_enabled_attr.attr, + NULL, +}; + +static const struct attribute_group anon_ctrl_attr_grp = { + .attrs = anon_ctrl_attrs, +}; + +static struct attribute *file_ctrl_attrs[] = { +#ifdef CONFIG_SHMEM + &thpsize_shmem_enabled_attr.attr, +#endif + NULL, +}; + +static const struct attribute_group file_ctrl_attr_grp = { + .attrs = file_ctrl_attrs, +}; + +static struct attribute *any_ctrl_attrs[] = { + NULL, +}; + +static const struct attribute_group any_ctrl_attr_grp = { + .attrs = any_ctrl_attrs, +}; + +static const struct kobj_type thpsize_ktype = { + .release = &thpsize_release, + .sysfs_ops = &kobj_sysfs_ops, +}; + +DEFINE_PER_CPU(struct mthp_stat, mthp_stats) = {{{0}}}; + +static unsigned long sum_mthp_stat(int order, enum mthp_stat_item item) +{ + unsigned long sum = 0; + int cpu; + + for_each_possible_cpu(cpu) { + struct mthp_stat *this = &per_cpu(mthp_stats, cpu); + + sum += this->stats[order][item]; + } + + return sum; +} + +#define DEFINE_MTHP_STAT_ATTR(_name, _index) \ +static ssize_t _name##_show(struct kobject *kobj, \ + struct kobj_attribute *attr, char *buf) \ +{ \ + int order = to_thpsize(kobj)->order; \ + \ + return sysfs_emit(buf, "%lu\n", sum_mthp_stat(order, _index)); \ +} \ +static struct kobj_attribute _name##_attr = __ATTR_RO(_name) + +DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC); +DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK); +DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); +DEFINE_MTHP_STAT_ATTR(collapse_alloc, MTHP_STAT_COLLAPSE_ALLOC); +DEFINE_MTHP_STAT_ATTR(collapse_alloc_failed, MTHP_STAT_COLLAPSE_ALLOC_FAILED); +DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT); +DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN); +DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK); +DEFINE_MTHP_STAT_ATTR(swpin_fallback_charge, MTHP_STAT_SWPIN_FALLBACK_CHARGE); +DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT); +DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK); +#ifdef CONFIG_SHMEM +DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC); +DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK); +DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); +#endif +DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); +DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); +DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); +DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON); +DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED); +DEFINE_MTHP_STAT_ATTR(collapse_exceed_swap_pte, MTHP_STAT_COLLAPSE_EXCEED_SWAP); +DEFINE_MTHP_STAT_ATTR(collapse_exceed_none_pte, MTHP_STAT_COLLAPSE_EXCEED_NONE); +DEFINE_MTHP_STAT_ATTR(collapse_exceed_shared_pte, MTHP_STAT_COLLAPSE_EXCEED_SHARED); + + +static struct attribute *anon_stats_attrs[] = { + &anon_fault_alloc_attr.attr, + &anon_fault_fallback_attr.attr, + &anon_fault_fallback_charge_attr.attr, +#ifndef CONFIG_SHMEM + &zswpout_attr.attr, + &swpin_attr.attr, + &swpin_fallback_attr.attr, + &swpin_fallback_charge_attr.attr, + &swpout_attr.attr, + &swpout_fallback_attr.attr, +#endif + &split_deferred_attr.attr, + &nr_anon_attr.attr, + &nr_anon_partially_mapped_attr.attr, + &collapse_exceed_swap_pte_attr.attr, + &collapse_exceed_none_pte_attr.attr, + &collapse_exceed_shared_pte_attr.attr, + NULL, +}; + +static struct attribute_group anon_stats_attr_grp = { + .name = "stats", + .attrs = anon_stats_attrs, +}; + +static struct attribute *file_stats_attrs[] = { +#ifdef CONFIG_SHMEM + &shmem_alloc_attr.attr, + &shmem_fallback_attr.attr, + &shmem_fallback_charge_attr.attr, +#endif + NULL, +}; + +static struct attribute_group file_stats_attr_grp = { + .name = "stats", + .attrs = file_stats_attrs, +}; + +static struct attribute *any_stats_attrs[] = { +#ifdef CONFIG_SHMEM + &zswpout_attr.attr, + &swpin_attr.attr, + &swpin_fallback_attr.attr, + &swpin_fallback_charge_attr.attr, + &swpout_attr.attr, + &swpout_fallback_attr.attr, +#endif + &split_attr.attr, + &split_failed_attr.attr, + &collapse_alloc_attr.attr, + &collapse_alloc_failed_attr.attr, + NULL, +}; + +static struct attribute_group any_stats_attr_grp = { + .name = "stats", + .attrs = any_stats_attrs, +}; + +static int sysfs_add_group(struct kobject *kobj, + const struct attribute_group *grp) +{ + int ret = -ENOENT; + + /* + * If the group is named, try to merge first, assuming the subdirectory + * was already created. This avoids the warning emitted by + * sysfs_create_group() if the directory already exists. + */ + if (grp->name) + ret = sysfs_merge_group(kobj, grp); + if (ret) + ret = sysfs_create_group(kobj, grp); + + return ret; +} + +static struct thpsize *thpsize_create(int order, struct kobject *parent) +{ + unsigned long size = (PAGE_SIZE << order) / SZ_1K; + struct thpsize *thpsize; + int ret = -ENOMEM; + + thpsize = kzalloc_obj(*thpsize); + if (!thpsize) + goto err; + + thpsize->order = order; + + ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, + "hugepages-%lukB", size); + if (ret) + goto err_put; + + + ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &any_stats_attr_grp); + if (ret) + goto err_put; + + if (BIT(order) & THP_ORDERS_ALL_ANON) { + ret = sysfs_add_group(&thpsize->kobj, &anon_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &anon_stats_attr_grp); + if (ret) + goto err_put; + } + + if (BIT(order) & THP_ORDERS_ALL_FILE_DEFAULT) { + ret = sysfs_add_group(&thpsize->kobj, &file_ctrl_attr_grp); + if (ret) + goto err_put; + + ret = sysfs_add_group(&thpsize->kobj, &file_stats_attr_grp); + if (ret) + goto err_put; + } + + return thpsize; +err_put: + kobject_put(&thpsize->kobj); +err: + return ERR_PTR(ret); +} + +static void thpsize_release(struct kobject *kobj) +{ + kfree(to_thpsize(kobj)); +} + +static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) +{ + int err; + struct thpsize *thpsize; + unsigned long orders; + int order; + + /* + * Default to setting PMD-sized THP to inherit the global setting and + * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time + * constant so we have to do this here. + */ + if (!anon_orders_configured) + huge_anon_orders_inherit = BIT(PMD_ORDER); + + *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); + if (unlikely(!*hugepage_kobj)) { + pr_err("failed to create transparent hugepage kobject\n"); + return -ENOMEM; + } + + err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); + if (err) { + pr_err("failed to register transparent hugepage group\n"); + goto delete_obj; + } + + err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); + if (err) { + pr_err("failed to register transparent hugepage group\n"); + goto remove_hp_group; + } + + orders = THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT; + order = highest_order(orders); + while (orders) { + thpsize = thpsize_create(order, *hugepage_kobj); + if (IS_ERR(thpsize)) { + pr_err("failed to create thpsize for order %d\n", order); + err = PTR_ERR(thpsize); + goto remove_all; + } + list_add(&thpsize->node, &thpsize_list); + order = next_order(&orders, order); + } + + return 0; + +remove_all: + hugepage_exit_sysfs(*hugepage_kobj); + return err; +remove_hp_group: + sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); +delete_obj: + kobject_put(*hugepage_kobj); + return err; +} + +static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) +{ + struct thpsize *thpsize, *tmp; + + list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) { + list_del(&thpsize->node); + kobject_put(&thpsize->kobj); + } + + sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); + sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); + kobject_put(hugepage_kobj); +} +#else +static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) +{ + return 0; +} + +static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) +{ +} +#endif /* CONFIG_SYSFS */ + +int folio_memcg_alloc_deferred(struct folio *folio) +{ + if (mem_cgroup_disabled()) + return 0; + return folio_memcg_list_lru_alloc(folio, &deferred_split_lru, GFP_KERNEL); +} + +static int __init thp_shrinker_init(void) +{ + deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | + SHRINKER_MEMCG_AWARE, + "thp-deferred_split"); + if (!deferred_split_shrinker) + return -ENOMEM; + + if (list_lru_init_memcg_key(&deferred_split_lru, + deferred_split_shrinker, + &deferred_split_key)) { + shrinker_free(deferred_split_shrinker); + return -ENOMEM; + } + + deferred_split_shrinker->count_objects = deferred_split_count; + deferred_split_shrinker->scan_objects = deferred_split_scan; + shrinker_register(deferred_split_shrinker); + + return huge_zero_init(); +} + +static void __init thp_shrinker_exit(void) +{ + shrinker_free(deferred_split_shrinker); + list_lru_destroy(&deferred_split_lru); + huge_zero_shrinker_exit(); +} + +static int __init hugepage_init(void) +{ + int err; + struct kobject *hugepage_kobj; + + if (!has_transparent_hugepage()) { + transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; + return -EINVAL; + } + + /* + * hugepages can't be allocated by the buddy allocator + */ + MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER); + + err = hugepage_init_sysfs(&hugepage_kobj); + if (err) + goto err_sysfs; + + err = khugepaged_init(); + if (err) + goto err_slab; + + err = thp_shrinker_init(); + if (err) + goto err_shrinker; + + /* + * By default disable transparent hugepages on smaller systems, + * where the extra memory used could hurt more than TLB overhead + * is likely to save. The admin can still enable it through /sys. + */ + if (totalram_pages() < MB_TO_PAGES(512)) { + transparent_hugepage_flags = 0; + return 0; + } + + err = start_stop_khugepaged(); + if (err) + goto err_khugepaged; + + return 0; +err_khugepaged: + thp_shrinker_exit(); +err_shrinker: + khugepaged_destroy(); +err_slab: + hugepage_exit_sysfs(hugepage_kobj); +err_sysfs: + return err; +} +subsys_initcall(hugepage_init); + +static int __init setup_transparent_hugepage(char *str) +{ + int ret = 0; + if (!str) + goto out; + if (!strcmp(str, "always")) { + set_bit(TRANSPARENT_HUGEPAGE_FLAG, + &transparent_hugepage_flags); + clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + &transparent_hugepage_flags); + ret = 1; + } else if (!strcmp(str, "madvise")) { + clear_bit(TRANSPARENT_HUGEPAGE_FLAG, + &transparent_hugepage_flags); + set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + &transparent_hugepage_flags); + ret = 1; + } else if (!strcmp(str, "never")) { + clear_bit(TRANSPARENT_HUGEPAGE_FLAG, + &transparent_hugepage_flags); + clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + &transparent_hugepage_flags); + ret = 1; + } +out: + if (!ret) + pr_warn("transparent_hugepage= cannot parse, ignored\n"); + return ret; +} +__setup("transparent_hugepage=", setup_transparent_hugepage); + +static char str_dup[PAGE_SIZE] __initdata; +static int __init setup_thp_anon(char *str) +{ + char *token, *range, *policy, *subtoken; + unsigned long always, inherit, madvise; + char *start_size, *end_size; + int start, end, nr; + char *p; + + if (!str || strlen(str) + 1 > PAGE_SIZE) + goto err; + strscpy(str_dup, str); + + always = huge_anon_orders_always; + madvise = huge_anon_orders_madvise; + inherit = huge_anon_orders_inherit; + p = str_dup; + while ((token = strsep(&p, ";")) != NULL) { + range = strsep(&token, ":"); + policy = token; + + if (!policy) + goto err; + + while ((subtoken = strsep(&range, ",")) != NULL) { + if (strchr(subtoken, '-')) { + start_size = strsep(&subtoken, "-"); + end_size = subtoken; + + start = get_order_from_str(start_size, THP_ORDERS_ALL_ANON); + end = get_order_from_str(end_size, THP_ORDERS_ALL_ANON); + } else { + start_size = end_size = subtoken; + start = end = get_order_from_str(subtoken, + THP_ORDERS_ALL_ANON); + } + + if (start == -EINVAL) { + pr_err("invalid size %s in thp_anon boot parameter\n", start_size); + goto err; + } + + if (end == -EINVAL) { + pr_err("invalid size %s in thp_anon boot parameter\n", end_size); + goto err; + } + + if (start < 0 || end < 0 || start > end) + goto err; + + nr = end - start + 1; + if (!strcmp(policy, "always")) { + bitmap_set(&always, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + } else if (!strcmp(policy, "madvise")) { + bitmap_set(&madvise, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&always, start, nr); + } else if (!strcmp(policy, "inherit")) { + bitmap_set(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&always, start, nr); + } else if (!strcmp(policy, "never")) { + bitmap_clear(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&always, start, nr); + } else { + pr_err("invalid policy %s in thp_anon boot parameter\n", policy); + goto err; + } + } + } + + huge_anon_orders_always = always; + huge_anon_orders_madvise = madvise; + huge_anon_orders_inherit = inherit; + anon_orders_configured = true; + return 1; + +err: + pr_warn("thp_anon=%s: error parsing string, ignoring setting\n", str); + return 0; +} +__setup("thp_anon=", setup_thp_anon); + +pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_WRITE)) + pmd = pmd_mkwrite(pmd, vma); + return pmd; +} + +static inline bool is_transparent_hugepage(const struct folio *folio) +{ + if (!folio_test_large(folio)) + return false; + + return is_huge_zero_folio(folio) || + folio_test_large_rmappable(folio); +} + +static unsigned long __thp_get_unmapped_area(struct file *filp, + unsigned long addr, unsigned long len, + loff_t off, unsigned long flags, unsigned long size, + vma_flags_t vma_flags) +{ + loff_t off_end = off + len; + loff_t off_align = round_up(off, size); + unsigned long len_pad, ret, off_sub; + + if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) + return 0; + + if (off_end <= off_align || (off_end - off_align) < size) + return 0; + + len_pad = len + size; + if (len_pad < len || (off + len_pad) < off) + return 0; + + ret = mm_get_unmapped_area_vmaflags(filp, addr, len_pad, + off >> PAGE_SHIFT, flags, + vma_flags); + + /* + * The failure might be due to length padding. The caller will retry + * without the padding. + */ + if (IS_ERR_VALUE(ret)) + return 0; + + /* + * Do not try to align to THP boundary if allocation at the address + * hint succeeds. + */ + if (ret == addr) + return addr; + + off_sub = (off - ret) & (size - 1); + + if (mm_flags_test(MMF_TOPDOWN, current->mm) && !off_sub) + return ret + size; + + ret += off_sub; + return ret; +} + +unsigned long thp_get_unmapped_area_vmaflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags, + vma_flags_t vma_flags) +{ + unsigned long ret; + loff_t off = (loff_t)pgoff << PAGE_SHIFT; + + ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, + vma_flags); + if (ret) + return ret; + + return mm_get_unmapped_area_vmaflags(filp, addr, len, pgoff, flags, + vma_flags); +} + +unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + return thp_get_unmapped_area_vmaflags(filp, addr, len, pgoff, flags, + EMPTY_VMA_FLAGS); +} +EXPORT_SYMBOL_GPL(thp_get_unmapped_area); + +static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, + unsigned long addr) +{ + gfp_t gfp = vma_thp_gfp_mask(vma); + const int order = HPAGE_PMD_ORDER; + struct folio *folio; + + folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK); + + if (unlikely(!folio)) { + count_vm_event(THP_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + return NULL; + } + + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { + folio_put(folio); + count_vm_event(THP_FAULT_FALLBACK); + count_vm_event(THP_FAULT_FALLBACK_CHARGE); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); + return NULL; + } + + if (folio_memcg_alloc_deferred(folio)) { + folio_put(folio); + count_vm_event(THP_FAULT_FALLBACK); + count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); + return NULL; + } + + folio_throttle_swaprate(folio, gfp); + + /* + * When a folio is not zeroed during allocation (__GFP_ZERO not used) + * or user folios require special handling, folio_zero_user() is used to + * make sure that the page corresponding to the faulting address will be + * hot in the cache after zeroing. + */ + if (user_alloc_needs_zeroing()) + folio_zero_user(folio, addr); + /* + * The memory barrier inside __folio_mark_uptodate makes sure that + * folio_zero_user writes become visible before the set_pmd_at() + * write. + */ + __folio_mark_uptodate(folio); + return folio; +} + +void map_anon_folio_pmd_nopf(struct folio *folio, pmd_t *pmd, + struct vm_area_struct *vma, unsigned long haddr) +{ + pmd_t entry; + + entry = folio_mk_pmd(folio, vma->vm_page_prot); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); + folio_add_lru_vma(folio, vma); + set_pmd_at(vma->vm_mm, haddr, pmd, entry); + update_mmu_cache_pmd(vma, haddr, pmd); + deferred_split_folio(folio, false); +} + +static void map_anon_folio_pmd_pf(struct folio *folio, pmd_t *pmd, + struct vm_area_struct *vma, unsigned long haddr) +{ + map_anon_folio_pmd_nopf(folio, pmd, vma, haddr); + add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); + count_vm_event(THP_FAULT_ALLOC); + count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); + count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); +} + +static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) +{ + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + struct vm_area_struct *vma = vmf->vma; + struct folio *folio; + pgtable_t pgtable; + vm_fault_t ret = 0; + + folio = vma_alloc_anon_folio_pmd(vma, vmf->address); + if (unlikely(!folio)) + return VM_FAULT_FALLBACK; + + pgtable = pte_alloc_one(vma->vm_mm); + if (unlikely(!pgtable)) { + ret = VM_FAULT_OOM; + goto release; + } + + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_none(*vmf->pmd))) { + goto unlock_release; + } else { + ret = check_stable_address_space(vma->vm_mm); + if (ret) + goto unlock_release; + + /* Deliver the page fault to userland */ + if (userfaultfd_missing(vma)) { + spin_unlock(vmf->ptl); + folio_put(folio); + pte_free(vma->vm_mm, pgtable); + ret = handle_userfault(vmf, VM_UFFD_MISSING); + VM_BUG_ON(ret & VM_FAULT_FALLBACK); + return ret; + } + pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); + map_anon_folio_pmd_pf(folio, vmf->pmd, vma, haddr); + mm_inc_nr_ptes(vma->vm_mm); + spin_unlock(vmf->ptl); + } + + return 0; +unlock_release: + spin_unlock(vmf->ptl); +release: + if (pgtable) + pte_free(vma->vm_mm, pgtable); + folio_put(folio); + return ret; + +} + +vm_fault_t do_huge_pmd_device_private(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + vm_fault_t ret = 0; + spinlock_t *ptl; + softleaf_t entry; + struct page *page; + struct folio *folio; + + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + vma_end_read(vma); + return VM_FAULT_RETRY; + } + + ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) { + spin_unlock(ptl); + return 0; + } + + entry = softleaf_from_pmd(vmf->orig_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); + vmf->page = page; + vmf->pte = NULL; + if (folio_trylock(folio)) { + folio_get(folio); + spin_unlock(ptl); + ret = page_pgmap(page)->ops->migrate_to_ram(vmf); + folio_unlock(folio); + folio_put(folio); + } else { + spin_unlock(ptl); + } + + return ret; +} + +/* + * always: directly stall for all thp allocations + * defer: wake kswapd and fail if not immediately available + * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise + * fail if not immediately available + * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately + * available + * never: never stall for any thp allocation + */ +gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) +{ + const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); + + /* Always do synchronous compaction */ + if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) + return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); + + /* Kick kcompactd and fail quickly */ + if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) + return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; + + /* Synchronous compaction if madvised, otherwise kick kcompactd */ + if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) + return GFP_TRANSHUGE_LIGHT | + (vma_madvised ? __GFP_DIRECT_RECLAIM : + __GFP_KSWAPD_RECLAIM); + + /* Only do synchronous compaction if madvised */ + if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) + return GFP_TRANSHUGE_LIGHT | + (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); + + return GFP_TRANSHUGE_LIGHT; +} + +/* Caller must hold page table lock. */ +static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, + struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, + struct folio *zero_folio) +{ + pmd_t entry; + entry = folio_mk_pmd(zero_folio, vma->vm_page_prot); + entry = pmd_mkspecial(entry); + pgtable_trans_huge_deposit(mm, pmd, pgtable); + set_pmd_at(mm, haddr, pmd, entry); + mm_inc_nr_ptes(mm); +} + +vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + vm_fault_t ret; + + if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) + return VM_FAULT_FALLBACK; + ret = vmf_anon_prepare(vmf); + if (ret) + return ret; + khugepaged_enter_vma(vma, vma->vm_flags); + + if (!(vmf->flags & FAULT_FLAG_WRITE) && + !mm_forbids_zeropage(vma->vm_mm) && + transparent_hugepage_use_zero_page()) { + pgtable_t pgtable; + struct folio *zero_folio; + vm_fault_t ret; + + pgtable = pte_alloc_one(vma->vm_mm); + if (unlikely(!pgtable)) + return VM_FAULT_OOM; + zero_folio = mm_get_huge_zero_folio(vma->vm_mm); + if (unlikely(!zero_folio)) { + pte_free(vma->vm_mm, pgtable); + count_vm_event(THP_FAULT_FALLBACK); + return VM_FAULT_FALLBACK; + } + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + ret = 0; + if (pmd_none(*vmf->pmd)) { + ret = check_stable_address_space(vma->vm_mm); + if (ret) { + spin_unlock(vmf->ptl); + pte_free(vma->vm_mm, pgtable); + } else if (userfaultfd_missing(vma)) { + spin_unlock(vmf->ptl); + pte_free(vma->vm_mm, pgtable); + ret = handle_userfault(vmf, VM_UFFD_MISSING); + VM_BUG_ON(ret & VM_FAULT_FALLBACK); + } else { + set_huge_zero_folio(pgtable, vma->vm_mm, vma, + haddr, vmf->pmd, zero_folio); + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); + spin_unlock(vmf->ptl); + } + } else { + spin_unlock(vmf->ptl); + pte_free(vma->vm_mm, pgtable); + } + return ret; + } + + return __do_huge_pmd_anonymous_page(vmf); +} + +struct folio_or_pfn { + union { + struct folio *folio; + unsigned long pfn; + }; + bool is_folio; +}; + +static vm_fault_t insert_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd, struct folio_or_pfn fop, pgprot_t prot, + bool write) +{ + struct mm_struct *mm = vma->vm_mm; + pgtable_t pgtable = NULL; + spinlock_t *ptl; + pmd_t entry; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; + + if (arch_needs_pgtable_deposit()) { + pgtable = pte_alloc_one(vma->vm_mm); + if (!pgtable) + return VM_FAULT_OOM; + } + + ptl = pmd_lock(mm, pmd); + if (!pmd_none(*pmd)) { + const unsigned long pfn = fop.is_folio ? folio_pfn(fop.folio) : + fop.pfn; + + if (write) { + if (pmd_pfn(*pmd) != pfn) { + WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); + goto out_unlock; + } + entry = pmd_mkyoung(*pmd); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) + update_mmu_cache_pmd(vma, addr, pmd); + } + goto out_unlock; + } + + if (fop.is_folio) { + entry = folio_mk_pmd(fop.folio, vma->vm_page_prot); + + if (is_huge_zero_folio(fop.folio)) { + entry = pmd_mkspecial(entry); + } else { + folio_get(fop.folio); + folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma); + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR); + } + } else { + entry = pmd_mkhuge(pfn_pmd(fop.pfn, prot)); + entry = pmd_mkspecial(entry); + } + if (write) { + entry = pmd_mkyoung(pmd_mkdirty(entry)); + entry = maybe_pmd_mkwrite(entry, vma); + } + + if (pgtable) { + pgtable_trans_huge_deposit(mm, pmd, pgtable); + mm_inc_nr_ptes(mm); + pgtable = NULL; + } + + set_pmd_at(mm, addr, pmd, entry); + update_mmu_cache_pmd(vma, addr, pmd); + +out_unlock: + spin_unlock(ptl); + if (pgtable) + pte_free(mm, pgtable); + return VM_FAULT_NOPAGE; +} + +/** + * vmf_insert_pfn_pmd - insert a pmd size pfn + * @vmf: Structure describing the fault + * @pfn: pfn to insert + * @write: whether it's a write fault + * + * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, unsigned long pfn, + bool write) +{ + unsigned long addr = vmf->address & PMD_MASK; + struct vm_area_struct *vma = vmf->vma; + pgprot_t pgprot = vma->vm_page_prot; + struct folio_or_pfn fop = { + .pfn = pfn, + }; + + /* + * If we had pmd_special, we could avoid all these restrictions, + * but we need to be consistent with PTEs and architectures that + * can't support a 'special' bit. + */ + BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); + BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == + (VM_PFNMAP|VM_MIXEDMAP)); + BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); + + pfnmap_setup_cachemode_pfn(pfn, &pgprot); + + return insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write); +} +EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); + +vm_fault_t vmf_insert_folio_pmd(struct vm_fault *vmf, struct folio *folio, + bool write) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PMD_MASK; + struct folio_or_pfn fop = { + .folio = folio, + .is_folio = true, + }; + + if (WARN_ON_ONCE(folio_order(folio) != PMD_ORDER)) + return VM_FAULT_SIGBUS; + + return insert_pmd(vma, addr, vmf->pmd, fop, vma->vm_page_prot, write); +} +EXPORT_SYMBOL_GPL(vmf_insert_folio_pmd); + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) +{ + if (likely(vma->vm_flags & VM_WRITE)) + pud = pud_mkwrite(pud); + return pud; +} + +static vm_fault_t insert_pud(struct vm_area_struct *vma, unsigned long addr, + pud_t *pud, struct folio_or_pfn fop, pgprot_t prot, bool write) +{ + struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; + pud_t entry; + + if (addr < vma->vm_start || addr >= vma->vm_end) + return VM_FAULT_SIGBUS; + + ptl = pud_lock(mm, pud); + if (!pud_none(*pud)) { + const unsigned long pfn = fop.is_folio ? folio_pfn(fop.folio) : + fop.pfn; + + if (write) { + if (WARN_ON_ONCE(pud_pfn(*pud) != pfn)) + goto out_unlock; + entry = pud_mkyoung(*pud); + entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); + if (pudp_set_access_flags(vma, addr, pud, entry, 1)) + update_mmu_cache_pud(vma, addr, pud); + } + goto out_unlock; + } + + if (fop.is_folio) { + entry = folio_mk_pud(fop.folio, vma->vm_page_prot); + + folio_get(fop.folio); + folio_add_file_rmap_pud(fop.folio, &fop.folio->page, vma); + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PUD_NR); + } else { + entry = pud_mkhuge(pfn_pud(fop.pfn, prot)); + entry = pud_mkspecial(entry); + } + if (write) { + entry = pud_mkyoung(pud_mkdirty(entry)); + entry = maybe_pud_mkwrite(entry, vma); + } + set_pud_at(mm, addr, pud, entry); + update_mmu_cache_pud(vma, addr, pud); +out_unlock: + spin_unlock(ptl); + return VM_FAULT_NOPAGE; +} + +/** + * vmf_insert_pfn_pud - insert a pud size pfn + * @vmf: Structure describing the fault + * @pfn: pfn to insert + * @write: whether it's a write fault + * + * Insert a pud size pfn. See vmf_insert_pfn() for additional info. + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, unsigned long pfn, + bool write) +{ + unsigned long addr = vmf->address & PUD_MASK; + struct vm_area_struct *vma = vmf->vma; + pgprot_t pgprot = vma->vm_page_prot; + struct folio_or_pfn fop = { + .pfn = pfn, + }; + + /* + * If we had pud_special, we could avoid all these restrictions, + * but we need to be consistent with PTEs and architectures that + * can't support a 'special' bit. + */ + BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); + BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == + (VM_PFNMAP|VM_MIXEDMAP)); + BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); + + pfnmap_setup_cachemode_pfn(pfn, &pgprot); + + return insert_pud(vma, addr, vmf->pud, fop, pgprot, write); +} +EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); + +/** + * vmf_insert_folio_pud - insert a pud size folio mapped by a pud entry + * @vmf: Structure describing the fault + * @folio: folio to insert + * @write: whether it's a write fault + * + * Return: vm_fault_t value. + */ +vm_fault_t vmf_insert_folio_pud(struct vm_fault *vmf, struct folio *folio, + bool write) +{ + struct vm_area_struct *vma = vmf->vma; + unsigned long addr = vmf->address & PUD_MASK; + struct folio_or_pfn fop = { + .folio = folio, + .is_folio = true, + }; + + if (WARN_ON_ONCE(folio_order(folio) != PUD_ORDER)) + return VM_FAULT_SIGBUS; + + return insert_pud(vma, addr, vmf->pud, fop, vma->vm_page_prot, write); +} +EXPORT_SYMBOL_GPL(vmf_insert_folio_pud); +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ + +/** + * touch_pmd - Mark page table pmd entry as accessed and dirty (for write) + * @vma: The VMA covering @addr + * @addr: The virtual address + * @pmd: pmd pointer into the page table mapping @addr + * @write: Whether it's a write access + * + * Return: whether the pmd entry is changed + */ +bool touch_pmd(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmd, bool write) +{ + pmd_t entry; + + entry = pmd_mkyoung(*pmd); + if (write) + entry = pmd_mkdirty(entry); + if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, + pmd, entry, write)) { + update_mmu_cache_pmd(vma, addr, pmd); + return true; + } + + return false; +} + +static void copy_huge_non_present_pmd( + struct mm_struct *dst_mm, struct mm_struct *src_mm, + pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, + pmd_t pmd, pgtable_t pgtable) +{ + softleaf_t entry = softleaf_from_pmd(pmd); + struct folio *src_folio; + + VM_WARN_ON_ONCE(!pmd_is_valid_softleaf(pmd)); + + if (softleaf_is_migration_write(entry) || + softleaf_is_migration_read_exclusive(entry)) { + entry = make_readable_migration_entry(swp_offset(entry)); + pmd = softleaf_to_pmd(entry); + if (pmd_swp_soft_dirty(*src_pmd)) + pmd = pmd_swp_mksoft_dirty(pmd); + if (pmd_swp_uffd(*src_pmd)) + pmd = pmd_swp_mkuffd(pmd); + set_pmd_at(src_mm, addr, src_pmd, pmd); + } else if (softleaf_is_device_private(entry)) { + /* + * For device private entries, since there are no + * read exclusive entries, writable = !readable + */ + if (softleaf_is_device_private_write(entry)) { + entry = make_readable_device_private_entry(swp_offset(entry)); + pmd = softleaf_to_pmd(entry); + + if (pmd_swp_soft_dirty(*src_pmd)) + pmd = pmd_swp_mksoft_dirty(pmd); + if (pmd_swp_uffd(*src_pmd)) + pmd = pmd_swp_mkuffd(pmd); + set_pmd_at(src_mm, addr, src_pmd, pmd); + } + + src_folio = softleaf_to_folio(entry); + VM_WARN_ON(!folio_test_large(src_folio)); + + folio_get(src_folio); + /* + * folio_try_dup_anon_rmap_pmd does not fail for + * device private entries. + */ + folio_try_dup_anon_rmap_pmd(src_folio, &src_folio->page, + dst_vma, src_vma); + } + + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + mm_inc_nr_ptes(dst_mm); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); + if (!userfaultfd_protected(dst_vma)) + pmd = pmd_swp_clear_uffd(pmd); + set_pmd_at(dst_mm, addr, dst_pmd, pmd); +} + +int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) +{ + spinlock_t *dst_ptl, *src_ptl; + struct page *src_page; + struct folio *src_folio; + pmd_t pmd; + pgtable_t pgtable = NULL; + int ret = -ENOMEM; + + pmd = pmdp_get_lockless(src_pmd); + if (unlikely(pmd_present(pmd) && pmd_special(pmd) && + !is_huge_zero_pmd(pmd))) { + dst_ptl = pmd_lock(dst_mm, dst_pmd); + src_ptl = pmd_lockptr(src_mm, src_pmd); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + /* + * No need to recheck the pmd, it can't change with write + * mmap lock held here. + * + * Meanwhile, making sure it's not a CoW VMA with writable + * mapping, otherwise it means either the anon page wrongly + * applied special bit, or we made the PRIVATE mapping be + * able to wrongly write to the backend MMIO. + */ + VM_WARN_ON_ONCE(is_cow_mapping(src_vma->vm_flags) && pmd_write(pmd)); + goto set_pmd; + } + + /* Skip if can be re-fill on fault */ + if (!vma_is_anonymous(dst_vma)) + return 0; + + pgtable = pte_alloc_one(dst_mm); + if (unlikely(!pgtable)) + goto out; + + dst_ptl = pmd_lock(dst_mm, dst_pmd); + src_ptl = pmd_lockptr(src_mm, src_pmd); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + + ret = -EAGAIN; + pmd = *src_pmd; + + if (unlikely(thp_migration_supported() && + pmd_is_valid_softleaf(pmd))) { + copy_huge_non_present_pmd(dst_mm, src_mm, dst_pmd, src_pmd, addr, + dst_vma, src_vma, pmd, pgtable); + ret = 0; + goto out_unlock; + } + + if (unlikely(!pmd_trans_huge(pmd))) { + pte_free(dst_mm, pgtable); + goto out_unlock; + } + /* + * When page table lock is held, the huge zero pmd should not be + * under splitting since we don't split the page itself, only pmd to + * a page table. + */ + if (is_huge_zero_pmd(pmd)) { + /* + * mm_get_huge_zero_folio() will never allocate a new + * folio here, since we already have a zero page to + * copy. It just takes a reference. + */ + mm_get_huge_zero_folio(dst_mm); + goto out_zero_page; + } + + src_page = pmd_page(pmd); + VM_BUG_ON_PAGE(!PageHead(src_page), src_page); + src_folio = page_folio(src_page); + + folio_get(src_folio); + if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, dst_vma, src_vma))) { + /* Page maybe pinned: split and retry the fault on PTEs. */ + folio_put(src_folio); + pte_free(dst_mm, pgtable); + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + __split_huge_pmd(src_vma, src_pmd, addr, false); + return -EAGAIN; + } + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); +out_zero_page: + mm_inc_nr_ptes(dst_mm); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); + + /* See __copy_present_ptes(): restore accessible protection. */ + if (!userfaultfd_protected(dst_vma)) { + if (userfaultfd_rwp(src_vma) && pmd_uffd(pmd)) + pmd = pmd_modify(pmd, dst_vma->vm_page_prot); + pmd = pmd_clear_uffd(pmd); + } + + pmdp_set_wrprotect(src_mm, addr, src_pmd); + pmd = pmd_wrprotect(pmd); +set_pmd: + pmd = pmd_mkold(pmd); + set_pmd_at(dst_mm, addr, dst_pmd, pmd); + + ret = 0; +out_unlock: + spin_unlock(src_ptl); + spin_unlock(dst_ptl); +out: + return ret; +} + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +void touch_pud(struct vm_area_struct *vma, unsigned long addr, + pud_t *pud, bool write) +{ + pud_t _pud; + + _pud = pud_mkyoung(*pud); + if (write) + _pud = pud_mkdirty(_pud); + if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, + pud, _pud, write)) + update_mmu_cache_pud(vma, addr, pud); +} + +int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, + pud_t *dst_pud, pud_t *src_pud, unsigned long addr, + struct vm_area_struct *vma) +{ + spinlock_t *dst_ptl, *src_ptl; + pud_t pud; + int ret; + + dst_ptl = pud_lock(dst_mm, dst_pud); + src_ptl = pud_lockptr(src_mm, src_pud); + spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); + + ret = -EAGAIN; + pud = *src_pud; + if (unlikely(!pud_trans_huge(pud))) + goto out_unlock; + + /* + * TODO: once we support anonymous pages, use + * folio_try_dup_anon_rmap_*() and split if duplicating fails. + */ + if (is_cow_mapping(vma->vm_flags) && pud_write(pud)) { + pudp_set_wrprotect(src_mm, addr, src_pud); + pud = pud_wrprotect(pud); + } + pud = pud_mkold(pud); + set_pud_at(dst_mm, addr, dst_pud, pud); + + ret = 0; +out_unlock: + spin_unlock(src_ptl); + spin_unlock(dst_ptl); + return ret; +} + +void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) +{ + bool write = vmf->flags & FAULT_FLAG_WRITE; + + vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); + if (unlikely(!pud_same(*vmf->pud, orig_pud))) + goto unlock; + + touch_pud(vmf->vma, vmf->address, vmf->pud, write); +unlock: + spin_unlock(vmf->ptl); +} +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ + +bool huge_pmd_set_accessed(struct vm_fault *vmf) +{ + bool write = vmf->flags & FAULT_FLAG_WRITE; + + if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) + return false; + + return touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); +} + +static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf) +{ + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + struct vm_area_struct *vma = vmf->vma; + struct mmu_notifier_range range; + struct folio *folio; + vm_fault_t ret = 0; + + folio = vma_alloc_anon_folio_pmd(vma, vmf->address); + if (unlikely(!folio)) + return VM_FAULT_FALLBACK; + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr, + haddr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) + goto release; + ret = check_stable_address_space(vma->vm_mm); + if (ret) + goto release; + (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd); + map_anon_folio_pmd_pf(folio, vmf->pmd, vma, haddr); + goto unlock; +release: + folio_put(folio); +unlock: + spin_unlock(vmf->ptl); + mmu_notifier_invalidate_range_end(&range); + return ret; +} + +vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) +{ + const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; + struct vm_area_struct *vma = vmf->vma; + struct folio *folio; + struct page *page; + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + pmd_t orig_pmd = vmf->orig_pmd; + + vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); + VM_BUG_ON_VMA(!vma->anon_vma, vma); + + if (is_huge_zero_pmd(orig_pmd)) { + vm_fault_t ret = do_huge_zero_wp_pmd(vmf); + + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + + /* Fallback to splitting PMD if THP cannot be allocated */ + goto fallback; + } + + spin_lock(vmf->ptl); + + if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; + } + + page = pmd_page(orig_pmd); + folio = page_folio(page); + VM_BUG_ON_PAGE(!PageHead(page), page); + + /* Early check when only holding the PT lock. */ + if (PageAnonExclusive(page)) + goto reuse; + + if (!folio_trylock(folio)) { + folio_get(folio); + spin_unlock(vmf->ptl); + folio_lock(folio); + spin_lock(vmf->ptl); + if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { + spin_unlock(vmf->ptl); + folio_unlock(folio); + folio_put(folio); + return 0; + } + folio_put(folio); + } + + /* Recheck after temporarily dropping the PT lock. */ + if (PageAnonExclusive(page)) { + folio_unlock(folio); + goto reuse; + } + + /* + * See do_wp_page(): we can only reuse the folio exclusively if + * there are no additional references. Note that we always drain + * the LRU cache immediately after adding a THP. + */ + if (folio_ref_count(folio) > + 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) + goto unlock_fallback; + if (folio_test_swapcache(folio)) + folio_free_swap(folio); + if (folio_ref_count(folio) == 1) { + pmd_t entry; + + folio_move_anon_rmap(folio, vma); + SetPageAnonExclusive(page); + folio_unlock(folio); +reuse: + if (unlikely(unshare)) { + spin_unlock(vmf->ptl); + return 0; + } + entry = pmd_mkyoung(orig_pmd); + entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); + spin_unlock(vmf->ptl); + return 0; + } + +unlock_fallback: + folio_unlock(folio); + spin_unlock(vmf->ptl); +fallback: + __split_huge_pmd(vma, vmf->pmd, vmf->address, false); + return VM_FAULT_FALLBACK; +} + +static inline bool can_change_pmd_writable(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmd) +{ + struct page *page; + + if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) + return false; + + /* Don't touch entries that are not even readable (NUMA hinting). */ + if (pmd_protnone(pmd)) + return false; + + /* Do we need write faults for softdirty tracking? */ + if (pmd_needs_soft_dirty_wp(vma, pmd)) + return false; + + /* Do we need write faults for uffd-wp tracking? */ + if (userfaultfd_huge_pmd_wp(vma, pmd)) + return false; + + if (!(vma->vm_flags & VM_SHARED)) { + /* See can_change_pte_writable(). */ + page = vm_normal_page_pmd(vma, addr, pmd); + return page && PageAnon(page) && PageAnonExclusive(page); + } + + /* See can_change_pte_writable(). */ + return pmd_dirty(pmd); +} + +vm_fault_t do_huge_pmd_uffd_rwp(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + pmd_t pmd; + + if (!userfaultfd_rwp_async(vma)) + return handle_userfault(vmf, VM_UFFD_RWP); + + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; + } + pmd = pmd_modify(vmf->orig_pmd, vma->vm_page_prot); + /* pmd_modify() preserves _PAGE_UFFD; drop it on resolution */ + pmd = pmd_clear_uffd(pmd); + pmd = pmd_mkyoung(pmd); + if (!pmd_write(pmd) && + vma_wants_manual_pte_write_upgrade(vma) && + can_change_pmd_writable(vma, vmf->address, pmd)) + pmd = pmd_mkwrite(pmd, vma); + set_pmd_at(vma->vm_mm, vmf->address & HPAGE_PMD_MASK, + vmf->pmd, pmd); + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); + spin_unlock(vmf->ptl); + return 0; +} + +/* NUMA hinting page fault entry point for trans huge pmds */ +vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct folio *folio; + unsigned long haddr = vmf->address & HPAGE_PMD_MASK; + int nid = NUMA_NO_NODE; + int target_nid, last_cpupid; + pmd_t pmd, old_pmd; + bool writable = false; + int flags = 0; + + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + old_pmd = pmdp_get(vmf->pmd); + + if (unlikely(!pmd_same(old_pmd, vmf->orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; + } + + pmd = pmd_modify(old_pmd, vma->vm_page_prot); + + /* + * Detect now whether the PMD could be writable; this information + * is only valid while holding the PT lock. + */ + writable = pmd_write(pmd); + if (!writable && vma_wants_manual_pte_write_upgrade(vma) && + can_change_pmd_writable(vma, vmf->address, pmd)) + writable = true; + + folio = vm_normal_folio_pmd(vma, haddr, pmd); + if (!folio) + goto out_map; + + nid = folio_nid(folio); + + target_nid = numa_migrate_check(folio, vmf, haddr, &flags, writable, + &last_cpupid); + if (target_nid == NUMA_NO_NODE) + goto out_map; + if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) { + flags |= TNF_MIGRATE_FAIL; + goto out_map; + } + /* The folio is isolated and isolation code holds a folio reference. */ + spin_unlock(vmf->ptl); + writable = false; + + if (!migrate_misplaced_folio(folio, target_nid)) { + flags |= TNF_MIGRATED; + nid = target_nid; + task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); + return 0; + } + + flags |= TNF_MIGRATE_FAIL; + vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); + if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) { + spin_unlock(vmf->ptl); + return 0; + } +out_map: + /* Restore the PMD */ + pmd = pmd_modify(pmdp_get(vmf->pmd), vma->vm_page_prot); + pmd = pmd_mkyoung(pmd); + if (writable) + pmd = pmd_mkwrite(pmd, vma); + set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); + update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); + spin_unlock(vmf->ptl); + + if (nid != NUMA_NO_NODE) + task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); + return 0; +} + +/* + * Return true if we do MADV_FREE successfully on entire pmd page. + * Otherwise, return false. + */ +bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, + pmd_t *pmd, unsigned long addr, unsigned long next) +{ + spinlock_t *ptl; + pmd_t orig_pmd; + struct folio *folio; + struct mm_struct *mm = tlb->mm; + bool ret = false; + + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); + + ptl = pmd_trans_huge_lock(pmd, vma); + if (!ptl) + goto out_unlocked; + + orig_pmd = *pmd; + if (is_huge_zero_pmd(orig_pmd)) + goto out; + + if (unlikely(!pmd_present(orig_pmd))) { + VM_WARN_ON_ONCE(!pmd_is_migration_entry(orig_pmd) && + !pmd_is_device_private_entry(orig_pmd)); + goto out; + } + + folio = pmd_folio(orig_pmd); + /* + * If other processes are mapping this folio, we couldn't discard + * the folio unless they all do MADV_FREE so let's skip the folio. + */ + if (folio_maybe_mapped_shared(folio)) + goto out; + + if (!folio_trylock(folio)) + goto out; + + /* + * If user want to discard part-pages of THP, split it so MADV_FREE + * will deactivate only them. + */ + if (next - addr != HPAGE_PMD_SIZE) { + folio_get(folio); + spin_unlock(ptl); + split_folio(folio); + folio_unlock(folio); + folio_put(folio); + goto out_unlocked; + } + + if (folio_test_dirty(folio)) + folio_clear_dirty(folio); + folio_unlock(folio); + + if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { + pmdp_invalidate(vma, addr, pmd); + orig_pmd = pmd_mkold(orig_pmd); + orig_pmd = pmd_mkclean(orig_pmd); + + set_pmd_at(mm, addr, pmd, orig_pmd); + tlb_remove_pmd_tlb_entry(tlb, pmd, addr); + } + + folio_mark_lazyfree(folio); + ret = true; +out: + spin_unlock(ptl); +out_unlocked: + return ret; +} + +static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) +{ + pgtable_t pgtable; + + pgtable = pgtable_trans_huge_withdraw(mm, pmd); + pte_free(mm, pgtable); + mm_dec_nr_ptes(mm); +} + +static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma, + pmd_t pmdval, struct folio *folio, bool is_present) +{ + const bool is_device_private = folio_is_device_private(folio); + + /* Present and device private folios are rmappable. */ + if (is_present || is_device_private) + folio_remove_rmap_pmd(folio, &folio->page, vma); + + if (folio_test_anon(folio)) { + add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); + } else { + add_mm_counter(mm, mm_counter_file(folio), + -HPAGE_PMD_NR); + + if (is_present && pmd_young(pmdval) && + likely(vma_has_recency(vma))) + folio_mark_accessed(folio); + } + + /* Device private folios are pinned. */ + if (is_device_private) + folio_put(folio); +} + +static struct folio *normal_or_softleaf_folio_pmd(struct vm_area_struct *vma, + unsigned long addr, pmd_t pmdval, bool is_present) +{ + if (is_present) + return vm_normal_folio_pmd(vma, addr, pmdval); + + if (!thp_migration_supported()) + WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); + return pmd_to_softleaf_folio(pmdval); +} + +static bool has_deposited_pgtable(struct vm_area_struct *vma, pmd_t pmdval, + struct folio *folio) +{ + /* Some architectures require unconditional depositing. */ + if (arch_needs_pgtable_deposit()) + return true; + + /* + * Huge zero always deposited except for DAX which handles itself, see + * set_huge_zero_folio(). + */ + if (is_huge_zero_pmd(pmdval)) + return !vma_is_dax(vma); + + /* + * Otherwise, only anonymous folios are deposited, see + * __do_huge_pmd_anonymous_page(). + */ + return folio && folio_test_anon(folio); +} + +/** + * zap_huge_pmd - Zap a huge THP which is of PMD size. + * @tlb: The MMU gather TLB state associated with the operation. + * @vma: The VMA containing the range to zap. + * @pmd: A pointer to the leaf PMD entry. + * @addr: The virtual address for the range to zap. + * + * Returns: %true on success, %false otherwise. + */ +bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, + pmd_t *pmd, unsigned long addr) +{ + struct mm_struct *mm = tlb->mm; + struct folio *folio = NULL; + bool is_present = false; + bool has_deposit; + spinlock_t *ptl; + pmd_t orig_pmd; + + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); + + ptl = __pmd_trans_huge_lock(pmd, vma); + if (!ptl) + return false; + /* + * For architectures like ppc64 we look at deposited pgtable + * when calling pmdp_huge_get_and_clear. So do the + * pgtable_trans_huge_withdraw after finishing pmdp related + * operations. + */ + orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, + tlb->fullmm); + arch_check_zapped_pmd(vma, orig_pmd); + tlb_remove_pmd_tlb_entry(tlb, pmd, addr); + + is_present = pmd_present(orig_pmd); + folio = normal_or_softleaf_folio_pmd(vma, addr, orig_pmd, is_present); + has_deposit = has_deposited_pgtable(vma, orig_pmd, folio); + if (folio) + zap_huge_pmd_folio(mm, vma, orig_pmd, folio, is_present); + if (has_deposit) + zap_deposited_table(mm, pmd); + + spin_unlock(ptl); + if (is_present && folio) + tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); + return true; +} + +#ifndef pmd_move_must_withdraw +static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, + spinlock_t *old_pmd_ptl, + struct vm_area_struct *vma) +{ + /* + * With split pmd lock we also need to move preallocated + * PTE page table if new_pmd is on different PMD page table. + * + * We also don't deposit and withdraw tables for file pages. + */ + return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); +} +#endif + +static pmd_t move_soft_dirty_pmd(pmd_t pmd) +{ + if (pgtable_supports_soft_dirty()) { + if (unlikely(pmd_is_migration_entry(pmd))) + pmd = pmd_swp_mksoft_dirty(pmd); + else if (pmd_present(pmd)) + pmd = pmd_mksoft_dirty(pmd); + } + + return pmd; +} + +static pmd_t clear_uffd_wp_pmd(pmd_t pmd) +{ + if (pmd_none(pmd)) + return pmd; + if (pmd_present(pmd)) + pmd = pmd_clear_uffd(pmd); + else + pmd = pmd_swp_clear_uffd(pmd); + + return pmd; +} + +bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) +{ + spinlock_t *old_ptl, *new_ptl; + pmd_t pmd; + struct mm_struct *mm = vma->vm_mm; + bool force_flush = false; + + /* + * The destination pmd shouldn't be established, free_pgtables() + * should have released it; but move_page_tables() might have already + * inserted a page table, if racing against shmem/file collapse. + */ + if (!pmd_none(*new_pmd)) { + VM_BUG_ON(pmd_trans_huge(*new_pmd)); + return false; + } + + /* + * We don't have to worry about the ordering of src and dst + * ptlocks because exclusive mmap_lock prevents deadlock. + */ + old_ptl = __pmd_trans_huge_lock(old_pmd, vma); + if (old_ptl) { + new_ptl = pmd_lockptr(mm, new_pmd); + if (new_ptl != old_ptl) + spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); + pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); + if (pmd_present(pmd)) + force_flush = true; + VM_BUG_ON(!pmd_none(*new_pmd)); + + if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { + pgtable_t pgtable; + pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); + pgtable_trans_huge_deposit(mm, new_pmd, pgtable); + } + pmd = move_soft_dirty_pmd(pmd); + if (vma_has_uffd_without_event_remap(vma)) { + /* + * See __copy_present_ptes(): normalise the RWP marker + * so the destination starts accessible instead of + * taking a numa-hinting fault on first access. Only the + * marker (protnone + uffd) needs it; leave other present + * PMDs in the VMA untouched. + */ + if (pmd_present(pmd) && userfaultfd_rwp(vma) && + pmd_uffd(pmd)) + pmd = pmd_modify(pmd, vma->vm_page_prot); + pmd = clear_uffd_wp_pmd(pmd); + } + set_pmd_at(mm, new_addr, new_pmd, pmd); + if (force_flush) + flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); + if (new_ptl != old_ptl) + spin_unlock(new_ptl); + spin_unlock(old_ptl); + return true; + } + return false; +} + +static void change_non_present_huge_pmd(struct mm_struct *mm, + unsigned long addr, pmd_t *pmd, bool uffd_prot, + bool uffd_prot_resolve) +{ + softleaf_t entry = softleaf_from_pmd(*pmd); + pmd_t newpmd; + + VM_WARN_ON(!pmd_is_valid_softleaf(*pmd)); + if (softleaf_is_migration_write(entry)) { + const struct folio *folio = softleaf_to_folio(entry); + + /* + * A protection check is difficult so + * just be safe and disable write + */ + if (folio_test_anon(folio)) + entry = make_readable_exclusive_migration_entry(swp_offset(entry)); + else + entry = make_readable_migration_entry(swp_offset(entry)); + newpmd = softleaf_to_pmd(entry); + if (pmd_swp_soft_dirty(*pmd)) + newpmd = pmd_swp_mksoft_dirty(newpmd); + } else if (softleaf_is_device_private_write(entry)) { + entry = make_readable_device_private_entry(swp_offset(entry)); + newpmd = softleaf_to_pmd(entry); + if (pmd_swp_uffd(*pmd)) + newpmd = pmd_swp_mkuffd(newpmd); + } else { + newpmd = *pmd; + } + + if (uffd_prot) + newpmd = pmd_swp_mkuffd(newpmd); + else if (uffd_prot_resolve) + newpmd = pmd_swp_clear_uffd(newpmd); + if (!pmd_same(*pmd, newpmd)) + set_pmd_at(mm, addr, pmd, newpmd); +} + +/* + * Returns + * - 0 if PMD could not be locked + * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary + * or if prot_numa but THP migration is not supported + * - HPAGE_PMD_NR if protections changed and TLB flush necessary + */ +int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, + pmd_t *pmd, unsigned long addr, pgprot_t newprot, + unsigned long cp_flags) +{ + struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; + pmd_t oldpmd, entry; + bool prot_numa = cp_flags & MM_CP_PROT_NUMA; + bool uffd_prot = cp_flags & (MM_CP_UFFD_WP | MM_CP_UFFD_RWP); + bool uffd_prot_resolve = cp_flags & + (MM_CP_UFFD_WP_RESOLVE | MM_CP_UFFD_RWP_RESOLVE); + int ret = 1; + + tlb_change_page_size(tlb, HPAGE_PMD_SIZE); + + if (prot_numa && !thp_migration_supported()) + return 1; + + ptl = __pmd_trans_huge_lock(pmd, vma); + if (!ptl) + return 0; + + if (thp_migration_supported() && pmd_is_valid_softleaf(*pmd)) { + change_non_present_huge_pmd(mm, addr, pmd, uffd_prot, + uffd_prot_resolve); + goto unlock; + } + + /* Already in the desired state */ + if (prot_numa && pmd_protnone(*pmd)) + goto unlock; + if ((cp_flags & MM_CP_UFFD_RWP) && pmd_protnone(*pmd) && pmd_uffd(*pmd)) + goto unlock; + + if (prot_numa) { + + /* + * Avoid trapping faults against the zero page. The read-only + * data is likely to be read-cached on the local CPU and + * local/remote hits to the zero page are not interesting. + */ + if (is_huge_zero_pmd(*pmd)) + goto unlock; + + if (!folio_can_map_prot_numa(pmd_folio(*pmd), vma, + vma_is_single_threaded_private(vma))) + goto unlock; + } + /* + * In case prot_numa, we are under mmap_read_lock(mm). It's critical + * to not clear pmd intermittently to avoid race with MADV_DONTNEED + * which is also under mmap_read_lock(mm): + * + * CPU0: CPU1: + * change_huge_pmd(prot_numa=1) + * pmdp_huge_get_and_clear_notify() + * madvise_dontneed() + * zap_pmd_range() + * pmd_trans_huge(*pmd) == 0 (without ptl) + * // skip the pmd + * set_pmd_at(); + * // pmd is re-established + * + * The race makes MADV_DONTNEED miss the huge pmd and don't clear it + * which may break userspace. + * + * pmdp_invalidate_ad() is required to make sure we don't miss + * dirty/young flags set by hardware. + */ + oldpmd = pmdp_invalidate_ad(vma, addr, pmd); + + entry = pmd_modify(oldpmd, newprot); + if (uffd_prot) + entry = pmd_mkuffd(entry); + else if (uffd_prot_resolve) + /* + * Leave the write bit to be handled by PF interrupt + * handler, then things like COW could be properly + * handled. + */ + entry = pmd_clear_uffd(entry); + + /* See change_pte_range(): preserve RWP protection across mprotect() */ + if (userfaultfd_rwp(vma) && pmd_uffd(entry)) + entry = pmd_modify(entry, PAGE_NONE); + + /* See change_pte_range(). */ + if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && + can_change_pmd_writable(vma, addr, entry)) + entry = pmd_mkwrite(entry, vma); + + ret = HPAGE_PMD_NR; + set_pmd_at(mm, addr, pmd, entry); + + if (huge_pmd_needs_flush(oldpmd, entry)) + tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); +unlock: + spin_unlock(ptl); + return ret; +} + +/* + * Returns: + * + * - 0: if pud leaf changed from under us + * - 1: if pud can be skipped + * - HPAGE_PUD_NR: if pud was successfully processed + */ +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +int change_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, + pud_t *pudp, unsigned long addr, pgprot_t newprot, + unsigned long cp_flags) +{ + struct mm_struct *mm = vma->vm_mm; + pud_t oldpud, entry; + spinlock_t *ptl; + + tlb_change_page_size(tlb, HPAGE_PUD_SIZE); + + /* NUMA balancing doesn't apply to dax */ + if (cp_flags & MM_CP_PROT_NUMA) + return 1; + + /* + * Huge entries on userfault-wp or userfault-rwp only work with + * anonymous, while we don't have anonymous PUDs yet. + */ + if (WARN_ON_ONCE(cp_flags & (MM_CP_UFFD_WP_ALL | MM_CP_UFFD_RWP_ALL))) + return 1; + + ptl = __pud_trans_huge_lock(pudp, vma); + if (!ptl) + return 0; + + /* + * Can't clear PUD or it can race with concurrent zapping. See + * change_huge_pmd(). + */ + oldpud = pudp_invalidate(vma, addr, pudp); + entry = pud_modify(oldpud, newprot); + set_pud_at(mm, addr, pudp, entry); + tlb_flush_pud_range(tlb, addr, HPAGE_PUD_SIZE); + + spin_unlock(ptl); + return HPAGE_PUD_NR; +} +#endif + +#ifdef CONFIG_USERFAULTFD +/* + * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by + * the caller, but it must return after releasing the page_table_lock. + * Just move the page from src_pmd to dst_pmd if possible. + * Return zero if succeeded in moving the page, -EAGAIN if it needs to be + * repeated by the caller, or other errors in case of failure. + */ +int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, + struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, + unsigned long dst_addr, unsigned long src_addr) +{ + pmd_t _dst_pmd, src_pmdval; + struct page *src_page; + struct folio *src_folio; + spinlock_t *src_ptl, *dst_ptl; + pgtable_t src_pgtable; + struct mmu_notifier_range range; + int err = 0; + + src_pmdval = *src_pmd; + src_ptl = pmd_lockptr(mm, src_pmd); + + lockdep_assert_held(src_ptl); + vma_assert_locked(src_vma); + vma_assert_locked(dst_vma); + + /* Sanity checks before the operation */ + if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) || + WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) { + spin_unlock(src_ptl); + return -EINVAL; + } + + if (!pmd_trans_huge(src_pmdval)) { + spin_unlock(src_ptl); + if (pmd_is_migration_entry(src_pmdval)) { + pmd_migration_entry_wait(mm, src_pmd); + return -EAGAIN; + } + return -ENOENT; + } + + src_page = pmd_page(src_pmdval); + + if (!is_huge_zero_pmd(src_pmdval)) { + if (unlikely(!PageAnonExclusive(src_page))) { + spin_unlock(src_ptl); + return -EBUSY; + } + + src_folio = page_folio(src_page); + folio_get(src_folio); + } else + src_folio = NULL; + + spin_unlock(src_ptl); + + flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE); + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr, + src_addr + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + + if (src_folio) + folio_lock(src_folio); + + dst_ptl = pmd_lockptr(mm, dst_pmd); + double_pt_lock(src_ptl, dst_ptl); + if (unlikely(!pmd_same(*src_pmd, src_pmdval) || + !pmd_same(*dst_pmd, dst_pmdval))) { + err = -EAGAIN; + goto unlock_ptls; + } + if (src_folio) { + if (folio_maybe_dma_pinned(src_folio) || + !PageAnonExclusive(&src_folio->page)) { + err = -EBUSY; + goto unlock_ptls; + } + + if (WARN_ON_ONCE(!folio_test_head(src_folio)) || + WARN_ON_ONCE(!folio_test_anon(src_folio))) { + err = -EBUSY; + goto unlock_ptls; + } + + src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); + /* Folio got pinned from under us. Put it back and fail the move. */ + if (folio_maybe_dma_pinned(src_folio)) { + set_pmd_at(mm, src_addr, src_pmd, src_pmdval); + err = -EBUSY; + goto unlock_ptls; + } + + folio_move_anon_rmap(src_folio, dst_vma); + src_folio->index = linear_page_index(dst_vma, dst_addr); + + _dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot); + /* Follow mremap() behavior and treat the entry dirty after the move */ + _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); + } else { + src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); + _dst_pmd = move_soft_dirty_pmd(src_pmdval); + _dst_pmd = clear_uffd_wp_pmd(_dst_pmd); + } + + /* Re-arm RWP on the moved PMD if dst_vma is RWP-registered. */ + if (userfaultfd_rwp(dst_vma)) { + _dst_pmd = pmd_modify(_dst_pmd, PAGE_NONE); + _dst_pmd = pmd_mkuffd(_dst_pmd); + } + + set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); + + src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd); + pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable); +unlock_ptls: + double_pt_unlock(src_ptl, dst_ptl); + /* unblock rmap walks */ + if (src_folio) + folio_unlock(src_folio); + mmu_notifier_invalidate_range_end(&range); + if (src_folio) + folio_put(src_folio); + return err; +} +#endif /* CONFIG_USERFAULTFD */ + +/* + * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. + * + * Note that if it returns page table lock pointer, this routine returns without + * unlocking page table lock. So callers must unlock it. + */ +spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) +{ + spinlock_t *ptl; + + ptl = pmd_lock(vma->vm_mm, pmd); + if (likely(pmd_is_huge(*pmd))) + return ptl; + spin_unlock(ptl); + return NULL; +} + +/* + * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. + * + * Note that if it returns page table lock pointer, this routine returns without + * unlocking page table lock. So callers must unlock it. + */ +spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) +{ + spinlock_t *ptl; + + ptl = pud_lock(vma->vm_mm, pud); + if (likely(pud_trans_huge(*pud))) + return ptl; + spin_unlock(ptl); + return NULL; +} + +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, + pud_t *pud, unsigned long addr) +{ + spinlock_t *ptl; + pud_t orig_pud; + + ptl = __pud_trans_huge_lock(pud, vma); + if (!ptl) + return 0; + + orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); + arch_check_zapped_pud(vma, orig_pud); + tlb_remove_pud_tlb_entry(tlb, pud, addr); + if (vma_is_special_huge(vma)) { + spin_unlock(ptl); + /* No zero page support yet */ + } else { + struct page *page = NULL; + struct folio *folio; + + /* No support for anonymous PUD pages or migration yet */ + VM_WARN_ON_ONCE(vma_is_anonymous(vma) || + !pud_present(orig_pud)); + + page = pud_page(orig_pud); + folio = page_folio(page); + folio_remove_rmap_pud(folio, page, vma); + add_mm_counter(tlb->mm, mm_counter_file(folio), -HPAGE_PUD_NR); + + spin_unlock(ptl); + tlb_remove_page_size(tlb, page, HPAGE_PUD_SIZE); + } + return 1; +} + +static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, + unsigned long haddr) +{ + struct folio *folio; + struct page *page; + pud_t old_pud; + + VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); + VM_BUG_ON_VMA(vma->vm_start > haddr, vma); + VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); + VM_BUG_ON(!pud_trans_huge(*pud)); + + count_vm_event(THP_SPLIT_PUD); + + old_pud = pudp_huge_clear_flush(vma, haddr, pud); + + if (!vma_is_dax(vma)) + return; + + page = pud_page(old_pud); + folio = page_folio(page); + + if (!folio_test_dirty(folio) && pud_dirty(old_pud)) + folio_mark_dirty(folio); + if (!folio_test_referenced(folio) && pud_young(old_pud)) + folio_set_referenced(folio); + folio_remove_rmap_pud(folio, page, vma); + add_mm_counter(vma->vm_mm, mm_counter_file(folio), + -HPAGE_PUD_NR); + folio_put(folio); +} + +void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, + unsigned long address) +{ + spinlock_t *ptl; + struct mmu_notifier_range range; + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, + address & HPAGE_PUD_MASK, + (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); + mmu_notifier_invalidate_range_start(&range); + ptl = pud_lock(vma->vm_mm, pud); + if (unlikely(!pud_trans_huge(*pud))) + goto out; + __split_huge_pud_locked(vma, pud, range.start); + +out: + spin_unlock(ptl); + mmu_notifier_invalidate_range_end(&range); +} +#else +void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, + unsigned long address) +{ +} +#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ + +static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, + unsigned long haddr, pmd_t *pmd) +{ + struct mm_struct *mm = vma->vm_mm; + pgtable_t pgtable; + pmd_t _pmd, old_pmd; + unsigned long addr; + pte_t *pte; + int i; + + /* + * Leave pmd empty until pte is filled note that it is fine to delay + * notification until mmu_notifier_invalidate_range_end() as we are + * replacing a zero pmd write protected page with a zero pte write + * protected page. + * + * See Documentation/mm/mmu_notifier.rst + */ + old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); + + pgtable = pgtable_trans_huge_withdraw(mm, pmd); + pmd_populate(mm, &_pmd, pgtable); + + pte = pte_offset_map(&_pmd, haddr); + VM_BUG_ON(!pte); + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + pte_t entry; + + entry = pfn_pte(zero_pfn(addr), vma->vm_page_prot); + entry = pte_mkspecial(entry); + if (pmd_uffd(old_pmd)) + entry = pte_mkuffd(entry); + + /* Restore PAGE_NONE so an RWP marker keeps trapping */ + if (userfaultfd_rwp(vma) && pmd_uffd(old_pmd)) + entry = pte_modify(entry, PAGE_NONE); + + VM_BUG_ON(!pte_none(ptep_get(pte))); + set_pte_at(mm, addr, pte, entry); + pte++; + } + pte_unmap(pte - 1); + smp_wmb(); /* make pte visible before pmd */ + pmd_populate(mm, pmd, pgtable); +} + +static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long haddr, bool freeze) +{ + struct mm_struct *mm = vma->vm_mm; + struct folio *folio; + struct page *page; + pgtable_t pgtable; + pmd_t old_pmd, _pmd; + bool soft_dirty, uffd_wp = false, young = false, write = false; + bool anon_exclusive = false, dirty = false; + unsigned long addr; + pte_t *pte; + int i; + + VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); + VM_BUG_ON_VMA(vma->vm_start > haddr, vma); + VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); + + VM_WARN_ON_ONCE(!pmd_is_valid_softleaf(*pmd) && !pmd_trans_huge(*pmd)); + + count_vm_event(THP_SPLIT_PMD); + + if (!vma_is_anonymous(vma)) { + old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); + /* + * We are going to unmap this huge page. So + * just go ahead and zap it + */ + if (arch_needs_pgtable_deposit()) + zap_deposited_table(mm, pmd); + if (vma_is_special_huge(vma)) + return; + if (unlikely(pmd_is_migration_entry(old_pmd))) { + const softleaf_t old_entry = softleaf_from_pmd(old_pmd); + + folio = softleaf_to_folio(old_entry); + } else if (is_huge_zero_pmd(old_pmd)) { + return; + } else { + page = pmd_page(old_pmd); + folio = page_folio(page); + if (!folio_test_dirty(folio) && pmd_dirty(old_pmd)) + folio_mark_dirty(folio); + if (!folio_test_referenced(folio) && pmd_young(old_pmd)) + folio_set_referenced(folio); + folio_remove_rmap_pmd(folio, page, vma); + add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); + folio_put(folio); + return; + } + add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); + return; + } + + if (is_huge_zero_pmd(*pmd)) { + /* + * FIXME: Do we want to invalidate secondary mmu by calling + * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below + * inside __split_huge_pmd() ? + * + * We are going from a zero huge page write protected to zero + * small page also write protected so it does not seems useful + * to invalidate secondary mmu at this time. + */ + return __split_huge_zero_page_pmd(vma, haddr, pmd); + } + + if (pmd_is_migration_entry(*pmd)) { + softleaf_t entry; + + old_pmd = *pmd; + entry = softleaf_from_pmd(old_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); + + soft_dirty = pmd_swp_soft_dirty(old_pmd); + uffd_wp = pmd_swp_uffd(old_pmd); + + write = softleaf_is_migration_write(entry); + if (PageAnon(page)) + anon_exclusive = softleaf_is_migration_read_exclusive(entry); + young = softleaf_is_migration_young(entry); + dirty = softleaf_is_migration_dirty(entry); + } else if (pmd_is_device_private_entry(*pmd)) { + softleaf_t entry; + + old_pmd = *pmd; + entry = softleaf_from_pmd(old_pmd); + page = softleaf_to_page(entry); + folio = page_folio(page); + + soft_dirty = pmd_swp_soft_dirty(old_pmd); + uffd_wp = pmd_swp_uffd(old_pmd); + + write = softleaf_is_device_private_write(entry); + anon_exclusive = PageAnonExclusive(page); + + /* + * Device private THP should be treated the same as regular + * folios w.r.t anon exclusive handling. See the comments for + * folio handling and anon_exclusive below. + */ + if (freeze && anon_exclusive && + folio_try_share_anon_rmap_pmd(folio, page)) + freeze = false; + if (!freeze) { + rmap_t rmap_flags = RMAP_NONE; + + folio_ref_add(folio, HPAGE_PMD_NR - 1); + if (anon_exclusive) + rmap_flags |= RMAP_EXCLUSIVE; + + folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, + vma, haddr, rmap_flags); + } + } else { + /* + * Up to this point the pmd is present and huge and userland has + * the whole access to the hugepage during the split (which + * happens in place). If we overwrite the pmd with the not-huge + * version pointing to the pte here (which of course we could if + * all CPUs were bug free), userland could trigger a small page + * size TLB miss on the small sized TLB while the hugepage TLB + * entry is still established in the huge TLB. Some CPU doesn't + * like that. See + * http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum + * 383 on page 105. Intel should be safe but is also warns that + * it's only safe if the permission and cache attributes of the + * two entries loaded in the two TLB is identical (which should + * be the case here). But it is generally safer to never allow + * small and huge TLB entries for the same virtual address to be + * loaded simultaneously. So instead of doing "pmd_populate(); + * flush_pmd_tlb_range();" we first mark the current pmd + * notpresent (atomically because here the pmd_trans_huge must + * remain set at all times on the pmd until the split is + * complete for this pmd), then we flush the SMP TLB and finally + * we write the non-huge version of the pmd entry with + * pmd_populate. + */ + old_pmd = pmdp_invalidate(vma, haddr, pmd); + page = pmd_page(old_pmd); + folio = page_folio(page); + if (pmd_dirty(old_pmd)) { + dirty = true; + folio_set_dirty(folio); + } + write = pmd_write(old_pmd); + young = pmd_young(old_pmd); + soft_dirty = pmd_soft_dirty(old_pmd); + uffd_wp = pmd_uffd(old_pmd); + + VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + + /* + * Without "freeze", we'll simply split the PMD, propagating the + * PageAnonExclusive() flag for each PTE by setting it for + * each subpage -- no need to (temporarily) clear. + * + * With "freeze" we want to replace mapped pages by + * migration entries right away. This is only possible if we + * managed to clear PageAnonExclusive() -- see + * set_pmd_migration_entry(). + * + * In case we cannot clear PageAnonExclusive(), split the PMD + * only and let try_to_migrate_one() fail later. + * + * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. + */ + anon_exclusive = PageAnonExclusive(page); + if (freeze && anon_exclusive && + folio_try_share_anon_rmap_pmd(folio, page)) + freeze = false; + if (!freeze) { + rmap_t rmap_flags = RMAP_NONE; + + folio_ref_add(folio, HPAGE_PMD_NR - 1); + if (anon_exclusive) + rmap_flags |= RMAP_EXCLUSIVE; + folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, + vma, haddr, rmap_flags); + } + } + + /* + * Withdraw the table only after we mark the pmd entry invalid. + * This's critical for some architectures (Power). + */ + pgtable = pgtable_trans_huge_withdraw(mm, pmd); + pmd_populate(mm, &_pmd, pgtable); + + pte = pte_offset_map(&_pmd, haddr); + VM_BUG_ON(!pte); + + /* + * Note that NUMA hinting access restrictions are not transferred to + * avoid any possibility of altering permissions across VMAs. + */ + if (freeze || pmd_is_migration_entry(old_pmd)) { + pte_t entry; + swp_entry_t swp_entry; + + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + if (write) + swp_entry = make_writable_migration_entry( + page_to_pfn(page + i)); + else if (anon_exclusive) + swp_entry = make_readable_exclusive_migration_entry( + page_to_pfn(page + i)); + else + swp_entry = make_readable_migration_entry( + page_to_pfn(page + i)); + if (young) + swp_entry = make_migration_entry_young(swp_entry); + if (dirty) + swp_entry = make_migration_entry_dirty(swp_entry); + entry = swp_entry_to_pte(swp_entry); + if (soft_dirty) + entry = pte_swp_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_swp_mkuffd(entry); + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + set_pte_at(mm, addr, pte + i, entry); + } + } else if (pmd_is_device_private_entry(old_pmd)) { + pte_t entry; + swp_entry_t swp_entry; + + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { + /* + * anon_exclusive was already propagated to the relevant + * pages corresponding to the pte entries when freeze + * is false. + */ + if (write) + swp_entry = make_writable_device_private_entry( + page_to_pfn(page + i)); + else + swp_entry = make_readable_device_private_entry( + page_to_pfn(page + i)); + /* + * Young and dirty bits are not progated via swp_entry + */ + entry = swp_entry_to_pte(swp_entry); + if (soft_dirty) + entry = pte_swp_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_swp_mkuffd(entry); + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + set_pte_at(mm, addr, pte + i, entry); + } + } else { + pte_t entry; + + entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); + if (write) + entry = pte_mkwrite(entry, vma); + if (!young) + entry = pte_mkold(entry); + /* NOTE: this may set soft-dirty too on some archs */ + if (dirty) + entry = pte_mkdirty(entry); + if (soft_dirty) + entry = pte_mksoft_dirty(entry); + if (uffd_wp) + entry = pte_mkuffd(entry); + + /* Restore PAGE_NONE so an RWP marker keeps trapping */ + if (userfaultfd_rwp(vma) && uffd_wp) + entry = pte_modify(entry, PAGE_NONE); + + for (i = 0; i < HPAGE_PMD_NR; i++) + VM_WARN_ON(!pte_none(ptep_get(pte + i))); + + set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); + } + pte_unmap(pte); + + if (!pmd_is_migration_entry(*pmd)) + folio_remove_rmap_pmd(folio, page, vma); + if (freeze) + put_page(page); + + smp_wmb(); /* make pte visible before pmd */ + pmd_populate(mm, pmd, pgtable); +} + +void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, bool freeze) +{ + VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); + if (pmd_trans_huge(*pmd) || pmd_is_valid_softleaf(*pmd)) + __split_huge_pmd_locked(vma, pmd, address, freeze); +} + +void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long address, bool freeze) +{ + spinlock_t *ptl; + struct mmu_notifier_range range; + + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, + address & HPAGE_PMD_MASK, + (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); + mmu_notifier_invalidate_range_start(&range); + ptl = pmd_lock(vma->vm_mm, pmd); + split_huge_pmd_locked(vma, range.start, pmd, freeze); + spin_unlock(ptl); + mmu_notifier_invalidate_range_end(&range); +} + +void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, + bool freeze) +{ + pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); + + if (!pmd) + return; + + __split_huge_pmd(vma, pmd, address, freeze); +} + +static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) +{ + /* + * If the new address isn't hpage aligned and it could previously + * contain an hugepage: check if we need to split an huge pmd. + */ + if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && + range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), + ALIGN(address, HPAGE_PMD_SIZE))) + split_huge_pmd_address(vma, address, false); +} + +void vma_adjust_trans_huge(struct vm_area_struct *vma, + unsigned long start, + unsigned long end, + struct vm_area_struct *next) +{ + /* Check if we need to split start first. */ + split_huge_pmd_if_needed(vma, start); + + /* Check if we need to split end next. */ + split_huge_pmd_if_needed(vma, end); + + /* If we're incrementing next->vm_start, we might need to split it. */ + if (next) + split_huge_pmd_if_needed(next, end); +} + +static void unmap_folio(struct folio *folio) +{ + enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | + TTU_BATCH_FLUSH; + + VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + + if (folio_test_pmd_mappable(folio)) + ttu_flags |= TTU_SPLIT_HUGE_PMD; + + /* + * Anon pages need migration entries to preserve them, but file + * pages can simply be left unmapped, then faulted back on demand. + * If that is ever changed (perhaps for mlock), update remap_page(). + */ + if (folio_test_anon(folio)) + try_to_migrate(folio, ttu_flags); + else + try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); + + try_to_unmap_flush(); +} + +static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp, + struct folio *folio) +{ + struct mm_struct *mm = vma->vm_mm; + int ref_count, map_count; + pmd_t orig_pmd = *pmdp; + + if (pmd_dirty(orig_pmd)) + folio_set_dirty(folio); + if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { + folio_set_swapbacked(folio); + return false; + } + + orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp); + + /* + * Syncing against concurrent GUP-fast: + * - clear PMD; barrier; read refcount + * - inc refcount; barrier; read PMD + */ + smp_mb(); + + ref_count = folio_ref_count(folio); + map_count = folio_mapcount(folio); + + /* + * Order reads for folio refcount and dirty flag + * (see comments in __remove_mapping()). + */ + smp_rmb(); + + /* + * If the folio or its PMD is redirtied at this point, or if there + * are unexpected references, we will give up to discard this folio + * and remap it. + * + * The only folio refs must be one from isolation plus the rmap(s). + */ + if (pmd_dirty(orig_pmd)) + folio_set_dirty(folio); + if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) { + folio_set_swapbacked(folio); + set_pmd_at(mm, addr, pmdp, orig_pmd); + return false; + } + + if (ref_count != map_count + 1) { + set_pmd_at(mm, addr, pmdp, orig_pmd); + return false; + } + + folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma); + zap_deposited_table(mm, pmdp); + add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); + if (vma->vm_flags & VM_LOCKED) + mlock_drain_local(); + folio_put(folio); + + return true; +} + +bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, + pmd_t *pmdp, struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); + VM_WARN_ON_FOLIO(folio_test_swapbacked(folio), folio); + VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE)); + + return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); +} + +static void remap_page(struct folio *folio, unsigned long nr, int flags) +{ + int i = 0; + + /* If unmap_folio() uses try_to_migrate() on file, remove this check */ + if (!folio_test_anon(folio)) + return; + for (;;) { + remove_migration_ptes(folio, folio, TTU_RMAP_LOCKED | flags); + i += folio_nr_pages(folio); + if (i >= nr) + break; + folio = folio_next(folio); + } +} + +static void lru_add_split_folio(struct folio *folio, struct folio *new_folio, + struct lruvec *lruvec, struct list_head *list) +{ + VM_BUG_ON_FOLIO(folio_test_lru(new_folio), folio); + lockdep_assert_held(&lruvec->lru_lock); + + if (folio_is_device_private(folio)) + return; + + if (list) { + /* page reclaim is reclaiming a huge page */ + VM_WARN_ON(folio_test_lru(folio)); + folio_get(new_folio); + list_add_tail(&new_folio->lru, list); + } else { + /* head is still on lru (and we have it frozen) */ + VM_WARN_ON(!folio_test_lru(folio)); + if (folio_test_unevictable(folio)) + new_folio->mlock_count = 0; + else + list_add_tail(&new_folio->lru, &folio->lru); + folio_set_lru(new_folio); + } +} + +static bool page_range_has_hwpoisoned(struct page *page, long nr_pages) +{ + for (; nr_pages; page++, nr_pages--) + if (PageHWPoison(page)) + return true; + return false; +} + +/* + * It splits @folio into @new_order folios and copies the @folio metadata to + * all the resulting folios. + */ +static void __split_folio_to_order(struct folio *folio, int old_order, + int new_order) +{ + /* Scan poisoned pages when split a poisoned folio to large folios */ + const bool handle_hwpoison = folio_test_has_hwpoisoned(folio) && new_order; + long new_nr_pages = 1 << new_order; + long nr_pages = 1 << old_order; + long i; + + folio_clear_has_hwpoisoned(folio); + + /* Check first new_nr_pages since the loop below skips them */ + if (handle_hwpoison && + page_range_has_hwpoisoned(folio_page(folio, 0), new_nr_pages)) + folio_set_has_hwpoisoned(folio); + /* + * Skip the first new_nr_pages, since the new folio from them have all + * the flags from the original folio. + */ + for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) { + struct page *new_head = &folio->page + i; + /* + * Careful: new_folio is not a "real" folio before we cleared PageTail. + * Don't pass it around before clear_compound_head(). + */ + struct folio *new_folio = (struct folio *)new_head; + + VM_BUG_ON_PAGE(atomic_read(&new_folio->_mapcount) != -1, new_head); + + /* + * Clone page flags before unfreezing refcount. + * + * After successful get_page_unless_zero() might follow flags change, + * for example lock_page() which set PG_waiters. + * + * Note that for mapped sub-pages of an anonymous THP, + * PG_anon_exclusive has been cleared in unmap_folio() and is stored in + * the migration entry instead from where remap_page() will restore it. + * We can still have PG_anon_exclusive set on effectively unmapped and + * unreferenced sub-pages of an anonymous THP: we can simply drop + * PG_anon_exclusive (-> PG_mappedtodisk) for these here. + */ + new_folio->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP; + new_folio->flags.f |= (folio->flags.f & + ((1L << PG_referenced) | + (1L << PG_swapbacked) | + (1L << PG_swapcache) | + (1L << PG_mlocked) | + (1L << PG_uptodate) | + (1L << PG_active) | + (1L << PG_workingset) | + (1L << PG_locked) | + (1L << PG_unevictable) | +#ifdef CONFIG_ARCH_USES_PG_ARCH_2 + (1L << PG_arch_2) | +#endif +#ifdef CONFIG_ARCH_USES_PG_ARCH_3 + (1L << PG_arch_3) | +#endif + (1L << PG_dirty) | + (1L << PG_dropbehind) | + LRU_GEN_MASK | LRU_REFS_MASK)); + + new_folio->mapping = folio->mapping; + new_folio->index = folio->index + i; + + /* + * page->private should not be set in tail pages. Warn once + * if private is unexpectedly set. Do it before swap.val assignment + * since private overlaps with swap.val. + */ + VM_WARN_ON_ONCE_PAGE(new_folio->private, new_head); + + if (folio_test_swapcache(folio)) + new_folio->swap.val = folio->swap.val + i; + + /* Page flags must be visible before we make the page non-compound. */ + smp_wmb(); + + /* + * Clear PageTail before unfreezing page refcount. + * + * After successful get_page_unless_zero() might follow put_page() + * which needs correct compound_head(). + */ + clear_compound_head(new_head); + if (new_order) { + prep_compound_page(new_head, new_order); + folio_set_large_rmappable(new_folio); + } + + /* + * PG_has_hwpoisoned is on the 2nd page, so set it after + * the compound head is prepped. + */ + if (handle_hwpoison && + page_range_has_hwpoisoned(new_head, new_nr_pages)) + folio_set_has_hwpoisoned(new_folio); + + if (folio_test_young(folio)) + folio_set_young(new_folio); + if (folio_test_idle(folio)) + folio_set_idle(new_folio); +#ifdef CONFIG_MEMCG + new_folio->memcg_data = folio->memcg_data; +#endif + + folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); + } + + if (new_order) + folio_set_order(folio, new_order); + else + ClearPageCompound(&folio->page); +} + +/** + * __split_unmapped_folio() - splits an unmapped @folio to lower order folios in + * two ways: uniform split or non-uniform split. + * @folio: the to-be-split folio + * @new_order: the smallest order of the after split folios (since buddy + * allocator like split generates folios with orders from @folio's + * order - 1 to new_order). + * @split_at: in buddy allocator like split, the folio containing @split_at + * will be split until its order becomes @new_order. + * @xas: xa_state pointing to folio->mapping->i_pages and locked by caller + * @mapping: @folio->mapping + * @split_type: if the split is uniform or not (buddy allocator like split) + * + * + * 1. uniform split: the given @folio into multiple @new_order small folios, + * where all small folios have the same order. This is done when + * split_type is SPLIT_TYPE_UNIFORM. + * 2. buddy allocator like (non-uniform) split: the given @folio is split into + * half and one of the half (containing the given page) is split into half + * until the given @folio's order becomes @new_order. This is done when + * split_type is SPLIT_TYPE_NON_UNIFORM. + * + * The high level flow for these two methods are: + * + * 1. uniform split: @xas is split with no expectation of failure and a single + * __split_folio_to_order() is called to split the @folio into @new_order + * along with stats update. + * 2. non-uniform split: folio_order - @new_order calls to + * __split_folio_to_order() are expected to be made in a for loop to split + * the @folio to one lower order at a time. The folio containing @split_at + * is split in each iteration. @xas is split into half in each iteration and + * can fail. A failed @xas split leaves split folios as is without merging + * them back. + * + * After splitting, the caller's folio reference will be transferred to the + * folio containing @split_at. The caller needs to unlock and/or free + * after-split folios if necessary. + * + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) + */ +static int __split_unmapped_folio(struct folio *folio, int new_order, + struct page *split_at, struct xa_state *xas, + struct address_space *mapping, enum split_type split_type) +{ + const bool is_anon = folio_test_anon(folio); + int old_order = folio_order(folio); + int start_order = split_type == SPLIT_TYPE_UNIFORM ? new_order : old_order - 1; + struct folio *old_folio = folio; + int split_order; + + /* + * split to new_order one order at a time. For uniform split, + * folio is split to new_order directly. + */ + for (split_order = start_order; + split_order >= new_order; + split_order--) { + int nr_new_folios = 1UL << (old_order - split_order); + + /* order-1 anonymous folio is not supported */ + if (is_anon && split_order == 1) + continue; + + if (mapping) { + /* + * uniform split has xas_split_alloc() called before + * irq is disabled to allocate enough memory, whereas + * non-uniform split can handle ENOMEM. + * Use the to-be-split folio, so that a parallel + * folio_try_get() waits on it until xarray is updated + * with after-split folios and the original one is + * unfrozen. + */ + if (split_type == SPLIT_TYPE_UNIFORM) { + xas_split(xas, old_folio, old_order); + } else { + xas_set_order(xas, folio->index, split_order); + xas_try_split(xas, old_folio, old_order); + if (xas_error(xas)) + return xas_error(xas); + } + } + + folio_split_memcg_refs(folio, old_order, split_order); + split_page_owner(&folio->page, old_order, split_order); + pgalloc_tag_split(folio, old_order, split_order); + __split_folio_to_order(folio, old_order, split_order); + + if (is_anon) { + mod_mthp_stat(old_order, MTHP_STAT_NR_ANON, -1); + mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, nr_new_folios); + } + /* + * If uniform split, the process is complete. + * If non-uniform, continue splitting the folio at @split_at + * as long as the next @split_order is >= @new_order. + */ + folio = page_folio(split_at); + old_order = split_order; + } + + return 0; +} + +/** + * folio_check_splittable() - check if a folio can be split to a given order + * @folio: folio to be split + * @new_order: the smallest order of the after split folios (since buddy + * allocator like split generates folios with orders from @folio's + * order - 1 to new_order). + * @split_type: uniform or non-uniform split + * + * folio_check_splittable() checks if @folio can be split to @new_order using + * @split_type method. The truncated folio check must come first. + * + * Context: folio must be locked. + * + * Return: 0 - @folio can be split to @new_order, otherwise an error number is + * returned. + */ +int folio_check_splittable(struct folio *folio, unsigned int new_order, + enum split_type split_type) +{ + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + /* + * Folios that just got truncated cannot get split. Signal to the + * caller that there was a race. + * + * TODO: this will also currently refuse folios without a mapping in the + * swapcache (shmem or to-be-anon folios). + */ + if (!folio->mapping && !folio_test_anon(folio)) + return -EBUSY; + + /* order-1 is not supported for anonymous THP. */ + if (folio_test_anon(folio) && new_order == 1) + return -EINVAL; + + /* + * swapcache folio could only be split to order 0 + * + * non-uniform split creates after-split folios with orders from + * folio_order(folio) - 1 to new_order, making it not suitable for any + * swapcache folio split. Only uniform split to order-0 can be used + * here. + */ + if ((split_type == SPLIT_TYPE_NON_UNIFORM || new_order) && folio_test_swapcache(folio)) { + return -EINVAL; + } + + if (is_huge_zero_folio(folio)) + return -EINVAL; + + if (folio_test_writeback(folio)) + return -EBUSY; + + return 0; +} + +/* Number of folio references from the pagecache or the swapcache. */ +static unsigned int folio_cache_ref_count(const struct folio *folio) +{ + if (folio_test_anon(folio) && !folio_test_swapcache(folio)) + return 0; + return folio_nr_pages(folio); +} + +static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int new_order, + struct page *split_at, struct xa_state *xas, + struct address_space *mapping, bool do_lru, + struct list_head *list, enum split_type split_type, + pgoff_t end, int *nr_shmem_dropped) +{ + struct folio *end_folio = folio_next(folio); + struct folio *new_folio, *next; + int old_order = folio_order(folio); + struct list_lru_one *lru; + bool dequeue_deferred; + int ret = 0; + + VM_WARN_ON_ONCE(!mapping && end); + /* + * If this folio can be on the deferred split queue, lock out + * the shrinker before freezing the ref. If the shrinker sees + * a 0-ref folio, it assumes it beat folio_put() to the list + * lock and must clean up the LRU state - the same dequeue we + * will do below as part of the split. + */ + dequeue_deferred = folio_test_anon(folio) && old_order > 1; + if (dequeue_deferred) { + struct mem_cgroup *memcg; + + rcu_read_lock(); + memcg = folio_memcg(folio); + lru = list_lru_lock(&deferred_split_lru, + folio_nid(folio), &memcg); + } + if (folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) { + struct swap_cluster_info *ci = NULL; + struct lruvec *lruvec; + + if (dequeue_deferred) { + __list_lru_del(&deferred_split_lru, lru, + &folio->_deferred_list, folio_nid(folio)); + if (folio_test_partially_mapped(folio)) { + folio_clear_partially_mapped(folio); + mod_mthp_stat(old_order, + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); + } + list_lru_unlock(lru); + rcu_read_unlock(); + } + + if (mapping) { + int nr = folio_nr_pages(folio); + + if (folio_test_pmd_mappable(folio) && + new_order < HPAGE_PMD_ORDER) { + if (folio_test_swapbacked(folio)) { + lruvec_stat_mod_folio(folio, + NR_SHMEM_THPS, -nr); + } else { + lruvec_stat_mod_folio(folio, + NR_FILE_THPS, -nr); + } + } + } + + if (folio_test_swapcache(folio)) { + if (mapping) { + VM_WARN_ON_ONCE_FOLIO(mapping, folio); + return -EINVAL; + } + + ci = swap_cluster_get_and_lock(folio); + } + + /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ + if (do_lru) + lruvec = folio_lruvec_lock(folio); + + ret = __split_unmapped_folio(folio, new_order, split_at, xas, + mapping, split_type); + + /* + * Unfreeze after-split folios and put them back to the right + * list. @folio should be kept frozon until page cache + * entries are updated with all the other after-split folios + * to prevent others seeing stale page cache entries. + * As a result, new_folio starts from the next folio of + * @folio. + */ + for (new_folio = folio_next(folio); new_folio != end_folio; + new_folio = next) { + unsigned long nr_pages = folio_nr_pages(new_folio); + + next = folio_next(new_folio); + + zone_device_private_split_cb(folio, new_folio); + + folio_ref_unfreeze(new_folio, + folio_cache_ref_count(new_folio) + 1); + + if (do_lru) + lru_add_split_folio(folio, new_folio, lruvec, list); + + /* + * Anonymous folio with swap cache. + * NOTE: shmem in swap cache is not supported yet. + */ + if (ci) { + __swap_cache_replace_folio(ci, folio, new_folio); + continue; + } + + /* Anonymous folio without swap cache */ + if (!mapping) + continue; + + /* Add the new folio to the page cache. */ + if (new_folio->index < end) { + __xa_store(&mapping->i_pages, new_folio->index, + new_folio, 0); + continue; + } + + VM_WARN_ON_ONCE(!nr_shmem_dropped); + /* Drop folio beyond EOF: ->index >= end */ + if (shmem_mapping(mapping) && nr_shmem_dropped) + *nr_shmem_dropped += nr_pages; + else if (folio_test_clear_dirty(new_folio)) + folio_account_cleaned( + new_folio, inode_to_wb(mapping->host)); + __filemap_remove_folio(new_folio, NULL); + folio_put_refs(new_folio, nr_pages); + } + + zone_device_private_split_cb(folio, NULL); + /* + * Unfreeze @folio only after all page cache entries, which + * used to point to it, have been updated with new folios. + * Otherwise, a parallel folio_try_get() can grab @folio + * and its caller can see stale page cache entries. + */ + folio_ref_unfreeze(folio, folio_cache_ref_count(folio) + 1); + + if (do_lru) + lruvec_unlock(lruvec); + + if (ci) + swap_cluster_unlock(ci); + } else { + if (dequeue_deferred) { + list_lru_unlock(lru); + rcu_read_unlock(); + } + return -EAGAIN; + } + + return ret; +} + +/** + * __folio_split() - split a folio at @split_at to a @new_order folio + * @folio: folio to split + * @new_order: the order of the new folio + * @split_at: a page within the new folio + * @lock_at: a page within @folio to be left locked to caller + * @list: after-split folios will be put on it if non NULL + * @split_type: perform uniform split or not (non-uniform split) + * + * It calls __split_unmapped_folio() to perform uniform and non-uniform split. + * It is in charge of checking whether the split is supported or not and + * preparing @folio for __split_unmapped_folio(). + * + * After splitting, the after-split folio containing @lock_at remains locked + * and others are unlocked: + * 1. for uniform split, @lock_at points to one of @folio's subpages; + * 2. for buddy allocator like (non-uniform) split, @lock_at points to @folio. + * + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) + */ +static int __folio_split(struct folio *folio, unsigned int new_order, + struct page *split_at, struct page *lock_at, + struct list_head *list, enum split_type split_type) +{ + XA_STATE(xas, &folio->mapping->i_pages, folio->index); + struct folio *end_folio = folio_next(folio); + bool is_anon = folio_test_anon(folio); + struct address_space *mapping = NULL; + struct anon_vma *anon_vma = NULL; + int old_order = folio_order(folio); + struct folio *new_folio, *next; + int nr_shmem_dropped = 0; + enum ttu_flags ttu_flags = 0; + int ret; + pgoff_t end = 0; + + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); + + if (folio != page_folio(split_at) || folio != page_folio(lock_at)) { + ret = -EINVAL; + goto out; + } + + if (new_order >= old_order) { + ret = -EINVAL; + goto out; + } + + ret = folio_check_splittable(folio, new_order, split_type); + if (ret) { + VM_WARN_ONCE(ret == -EINVAL, "Tried to split an unsplittable folio"); + goto out; + } + + if (is_anon) { + /* + * The caller does not necessarily hold an mmap_lock that would + * prevent the anon_vma disappearing so we first we take a + * reference to it and then lock the anon_vma for write. This + * is similar to folio_lock_anon_vma_read except the write lock + * is taken to serialise against parallel split or collapse + * operations. + */ + anon_vma = folio_get_anon_vma(folio); + if (!anon_vma) { + ret = -EBUSY; + goto out; + } + anon_vma_lock_write(anon_vma); + mapping = NULL; + } else { + unsigned int min_order; + gfp_t gfp; + + mapping = folio->mapping; + min_order = mapping_min_folio_order(mapping); + if (new_order < min_order) { + ret = -EINVAL; + goto out; + } + + gfp = current_gfp_context(mapping_gfp_mask(mapping) & + GFP_RECLAIM_MASK); + + if (!filemap_release_folio(folio, gfp)) { + ret = -EBUSY; + goto out; + } + + mapping_set_update(&xas, mapping); + + if (split_type == SPLIT_TYPE_UNIFORM) { + xas_set_order(&xas, folio->index, new_order); + xas_split_alloc(&xas, folio, old_order, gfp); + if (xas_error(&xas)) { + ret = xas_error(&xas); + goto out; + } + } + + anon_vma = NULL; + i_mmap_lock_read(mapping); + + /* + *__split_unmapped_folio() may need to trim off pages beyond + * EOF: but on 32-bit, i_size_read() takes an irq-unsafe + * seqlock, which cannot be nested inside the page tree lock. + * So note end now: i_size itself may be changed at any moment, + * but folio lock is good enough to serialize the trimming. + */ + end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); + if (shmem_mapping(mapping)) + end = shmem_fallocend(mapping->host, end); + } + + /* + * Racy check if we can split the page, before unmap_folio() will + * split PMDs + */ + if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) { + ret = -EAGAIN; + goto out_unlock; + } + + unmap_folio(folio); + + /* block interrupt reentry in xa_lock and spinlock */ + local_irq_disable(); + if (mapping) { + /* + * Check if the folio is present in page cache. + * We assume all tail are present too, if folio is there. + */ + xas_lock(&xas); + xas_reset(&xas); + if (xas_load(&xas) != folio) { + ret = -EAGAIN; + goto fail; + } + } + + ret = __folio_freeze_and_split_unmapped(folio, new_order, split_at, &xas, mapping, + true, list, split_type, end, &nr_shmem_dropped); +fail: + if (mapping) + xas_unlock(&xas); + + local_irq_enable(); + + if (nr_shmem_dropped) + shmem_uncharge(mapping->host, nr_shmem_dropped); + + if (!ret && is_anon && !folio_is_device_private(folio)) + ttu_flags = TTU_USE_SHARED_ZEROPAGE; + + remap_page(folio, 1 << old_order, ttu_flags); + + /* + * Drop the mapping while the inode is still pinned. @folio stays + * locked and present in the page cache until the loop below, so + * eviction cannot free the inode yet; @lock_at is not enough, it may + * be a tail beyond EOF that the split already dropped from the page + * cache. Nothing past this point may touch the inode or the mapping. + */ + if (mapping) { + i_mmap_unlock_read(mapping); + mapping = NULL; + } + + /* + * Unlock all after-split folios except the one containing + * @lock_at page. If @folio is not split, it will be kept locked. + */ + for (new_folio = folio; new_folio != end_folio; new_folio = next) { + next = folio_next(new_folio); + if (new_folio == page_folio(lock_at)) + continue; + + folio_unlock(new_folio); + /* + * Subpages whose mapping has been zapped may be freed + * earlier, but freeing them requires taking the + * lru_lock, so we defer put_page() on tail pages until + * after the split completes. + */ + free_folio_and_swap_cache(new_folio); + } + +out_unlock: + if (anon_vma) { + anon_vma_unlock_write(anon_vma); + put_anon_vma(anon_vma); + } + if (mapping) + i_mmap_unlock_read(mapping); +out: + xas_destroy(&xas); + if (is_pmd_order(old_order)) + count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); + count_mthp_stat(old_order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); + return ret; +} + +/** + * folio_split_unmapped() - split a large anon folio that is already unmapped + * @folio: folio to split + * @new_order: the order of folios after split + * + * This function is a helper for splitting folios that have already been + * unmapped. The use case is that the device or the CPU can refuse to migrate + * THP pages in the middle of migration, due to allocation issues on either + * side. + * + * anon_vma_lock is not required to be held, mmap_read_lock() or + * mmap_write_lock() should be held. @folio is expected to be locked by the + * caller. device-private and non device-private folios are supported along + * with folios that are in the swapcache. @folio should also be unmapped and + * isolated from LRU (if applicable) + * + * Upon return, the folio is not remapped, split folios are not added to LRU, + * free_folio_and_swap_cache() is not called, and new folios remain locked. + * + * Return: 0 on success, -EAGAIN if the folio cannot be split (e.g., due to + * insufficient reference count or extra pins). + */ +int folio_split_unmapped(struct folio *folio, unsigned int new_order) +{ + int ret = 0; + + VM_WARN_ON_ONCE_FOLIO(folio_mapped(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); + VM_WARN_ON_ONCE_FOLIO(!folio_test_anon(folio), folio); + + if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) + return -EAGAIN; + + local_irq_disable(); + ret = __folio_freeze_and_split_unmapped(folio, new_order, &folio->page, NULL, + NULL, false, NULL, SPLIT_TYPE_UNIFORM, + 0, NULL); + local_irq_enable(); + return ret; +} + +/* + * This function splits a large folio into smaller folios of order @new_order. + * @page can point to any page of the large folio to split. The split operation + * does not change the position of @page. + * + * Prerequisites: + * + * 1) The caller must hold a reference on the @page's owning folio, also known + * as the large folio. + * + * 2) The large folio must be locked. + * + * 3) The folio must not be pinned. Any unexpected folio references, including + * GUP pins, will result in the folio not getting split; instead, the caller + * will receive an -EAGAIN. + * + * 4) @new_order > 1, usually. Splitting to order-1 anonymous folios is not + * supported for non-file-backed folios, because folio->_deferred_list, which + * is used by partially mapped folios, is stored in subpage 2, but an order-1 + * folio only has subpages 0 and 1. File-backed order-1 folios are supported, + * since they do not use _deferred_list. + * + * After splitting, the caller's folio reference will be transferred to @page, + * resulting in a raised refcount of @page after this call. The other pages may + * be freed if they are not mapped. + * + * If @list is null, tail pages will be added to LRU list, otherwise, to @list. + * + * Pages in @new_order will inherit the mapping, flags, and so on from the + * huge page. + * + * Returns 0 if the huge page was split successfully. + * + * Returns -EAGAIN if the folio has unexpected reference (e.g., GUP) or if + * the folio was concurrently removed from the page cache. + * + * Returns -EBUSY when trying to split the huge zeropage, if the folio is + * under writeback, if fs-specific folio metadata cannot currently be + * released, or if some unexpected race happened (e.g., anon VMA disappeared, + * truncation). + * + * Callers should ensure that the order respects the address space mapping + * min-order if one is set for non-anonymous folios. + * + * Returns -EINVAL when trying to split to an order that is incompatible + * with the folio. Splitting to order 0 is compatible with all folios. + */ +int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list, + unsigned int new_order) +{ + struct folio *folio = page_folio(page); + + return __folio_split(folio, new_order, &folio->page, page, list, + SPLIT_TYPE_UNIFORM); +} + +/** + * folio_split() - split a folio at @split_at to a @new_order folio + * @folio: folio to split + * @new_order: the order of the new folio + * @split_at: a page within the new folio + * @list: after-split folios are added to @list if not null, otherwise to LRU + * list + * + * It has the same prerequisites and returns as + * split_huge_page_to_list_to_order(). + * + * Split a folio at @split_at to a new_order folio, leave the + * remaining subpages of the original folio as large as possible. For example, + * in the case of splitting an order-9 folio at its third order-3 subpages to + * an order-3 folio, there are 2^(9-3)=64 order-3 subpages in the order-9 folio. + * After the split, there will be a group of folios with different orders and + * the new folio containing @split_at is marked in bracket: + * [order-4, {order-3}, order-3, order-5, order-6, order-7, order-8]. + * + * After split, folio is left locked for caller. + * + * Return: 0 - successful, <0 - failed (if -ENOMEM is returned, @folio might be + * split but not to @new_order, the caller needs to check) + */ +int folio_split(struct folio *folio, unsigned int new_order, + struct page *split_at, struct list_head *list) +{ + return __folio_split(folio, new_order, split_at, &folio->page, list, + SPLIT_TYPE_NON_UNIFORM); +} + +/** + * min_order_for_split() - get the minimum order @folio can be split to + * @folio: folio to split + * + * min_order_for_split() tells the minimum order @folio can be split to. + * If a file-backed folio is truncated, 0 will be returned. Any subsequent + * split attempt should get -EBUSY from split checking code. + * + * Return: @folio's minimum order for split + */ +unsigned int min_order_for_split(struct folio *folio) +{ + if (folio_test_anon(folio)) + return 0; + + /* + * If the folio got truncated, we don't know the previous mapping and + * consequently the old min order. But it doesn't matter, as any split + * attempt will immediately fail with -EBUSY as the folio cannot get + * split until freed. + */ + if (!folio->mapping) + return 0; + + return mapping_min_folio_order(folio->mapping); +} + +int split_folio_to_list(struct folio *folio, struct list_head *list) +{ + return split_huge_page_to_list_to_order(&folio->page, list, 0); +} + +/* + * __folio_unqueue_deferred_split() is not to be called directly: + * the folio_unqueue_deferred_split() inline wrapper in mm/internal.h + * limits its calls to those folios which may have a _deferred_list for + * queueing THP splits, and that list is (racily observed to be) non-empty. + * + * It is unsafe to call folio_unqueue_deferred_split() until folio refcount is + * zero: because even when the list_lru lock is held, a non-empty + * _deferred_list might be in use on deferred_split_scan()'s unlocked + * on-stack list. + * + * The list_lru sublist is determined by folio's memcg: it is therefore + * important to unqueue deferred split before changing folio memcg. + */ +bool __folio_unqueue_deferred_split(struct folio *folio) +{ + struct mem_cgroup *memcg; + struct list_lru_one *lru; + int nid = folio_nid(folio); + unsigned long flags; + bool unqueued = false; + + WARN_ON_ONCE(folio_ref_count(folio)); + WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg_charged(folio)); + + rcu_read_lock(); + memcg = folio_memcg(folio); + lru = list_lru_lock_irqsave(&deferred_split_lru, nid, &memcg, &flags); + if (__list_lru_del(&deferred_split_lru, lru, &folio->_deferred_list, nid)) { + if (folio_test_partially_mapped(folio)) { + folio_clear_partially_mapped(folio); + mod_mthp_stat(folio_order(folio), + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); + } + unqueued = true; + } + list_lru_unlock_irqrestore(lru, &flags); + rcu_read_unlock(); + + return unqueued; /* useful for debug warnings */ +} + +/* partially_mapped=false won't clear PG_partially_mapped folio flag */ +void deferred_split_folio(struct folio *folio, bool partially_mapped) +{ + struct list_lru_one *lru; + int nid; + struct mem_cgroup *memcg; + unsigned long flags; + + /* + * Order 1 folios have no space for a deferred list, but we also + * won't waste much memory by not adding them to the deferred list. + */ + if (folio_order(folio) <= 1) + return; + + if (!partially_mapped && !split_underused_thp) + return; + + /* + * Exclude swapcache: originally to avoid a corrupt deferred split + * queue. Nowadays that is fully prevented by __memcg1_swapout(); + * but if page reclaim is already handling the same folio, it is + * unnecessary to handle it again in the shrinker, so excluding + * swapcache here may still be a useful optimization. + */ + if (folio_test_swapcache(folio)) + return; + + nid = folio_nid(folio); + + rcu_read_lock(); + memcg = folio_memcg(folio); + lru = list_lru_lock_irqsave(&deferred_split_lru, nid, &memcg, &flags); + if (partially_mapped) { + if (!folio_test_partially_mapped(folio)) { + folio_set_partially_mapped(folio); + if (folio_test_pmd_mappable(folio)) + count_vm_event(THP_DEFERRED_SPLIT_PAGE); + count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, 1); + } + } else { + /* partially mapped folios cannot become non-partially mapped */ + VM_WARN_ON_FOLIO(folio_test_partially_mapped(folio), folio); + } + __list_lru_add(&deferred_split_lru, lru, &folio->_deferred_list, nid, memcg); + list_lru_unlock_irqrestore(lru, &flags); + rcu_read_unlock(); +} + +static unsigned long deferred_split_count(struct shrinker *shrink, + struct shrink_control *sc) +{ + unsigned long count; + + count = list_lru_shrink_count(&deferred_split_lru, sc); + return count ?: SHRINK_EMPTY; +} + +static bool thp_underused(struct folio *folio) +{ + int num_zero_pages = 0, num_filled_pages = 0; + int i; + + if (khugepaged_max_ptes_none == HPAGE_PMD_NR - 1) + return false; + + if (folio_contain_hwpoisoned_page(folio)) + return false; + + for (i = 0; i < folio_nr_pages(folio); i++) { + if (pages_identical(folio_page(folio, i), ZERO_PAGE(0))) { + if (++num_zero_pages > khugepaged_max_ptes_none) + return true; + } else { + /* + * Another path for early exit once the number + * of non-zero filled pages exceeds threshold. + */ + if (++num_filled_pages >= HPAGE_PMD_NR - khugepaged_max_ptes_none) + return false; + } + } + return false; +} + +static enum lru_status deferred_split_isolate(struct list_head *item, + struct list_lru_one *lru, + void *cb_arg) +{ + struct folio *folio = container_of(item, struct folio, _deferred_list); + struct list_head *freeable = cb_arg; + + if (folio_try_get(folio)) { + list_lru_isolate_move(lru, item, freeable); + return LRU_REMOVED; + } + + /* + * We lost race with folio_put(). Read folio state before the + * isolate: folio_unqueue_deferred_split() checks list_empty() + * locklessly, so once removed the folio can be freed any time. + */ + if (folio_test_partially_mapped(folio)) { + folio_clear_partially_mapped(folio); + mod_mthp_stat(folio_order(folio), + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); + } + list_lru_isolate(lru, item); + return LRU_REMOVED; +} + +static unsigned long deferred_split_scan(struct shrinker *shrink, + struct shrink_control *sc) +{ + LIST_HEAD(dispose); + struct folio *folio, *next; + int split = 0; + unsigned long isolated; + + isolated = list_lru_shrink_walk_irq(&deferred_split_lru, sc, + deferred_split_isolate, &dispose); + + list_for_each_entry_safe(folio, next, &dispose, _deferred_list) { + bool did_split = false; + bool underused = false; + + list_del_init(&folio->_deferred_list); + + if (!folio_test_partially_mapped(folio)) { + /* + * See try_to_map_unused_to_zeropage(): we cannot + * optimize zero-filled pages after splitting an + * mlocked folio. + */ + if (folio_test_mlocked(folio)) + goto next; + underused = thp_underused(folio); + if (!underused) + goto next; + } + if (!folio_trylock(folio)) + goto requeue; + if (!split_folio(folio)) { + did_split = true; + if (underused) + count_vm_event(THP_UNDERUSED_SPLIT_PAGE); + split++; + } + folio_unlock(folio); +next: + /* + * If thp_underused() returns false, or if split_folio() + * succeeds, or if split_folio() fails in the case it was + * underused, then consider it used and don't add it back to + * split_queue. + */ + if (!did_split && folio_test_partially_mapped(folio)) { +requeue: + rcu_read_lock(); + list_lru_add_irq(&deferred_split_lru, + &folio->_deferred_list, + folio_nid(folio), + folio_memcg(folio)); + rcu_read_unlock(); + } + folio_put(folio); + } + + if (!split && !isolated) + return SHRINK_STOP; + return split; +} + +#ifdef CONFIG_DEBUG_FS +static void split_huge_pages_all(void) +{ + struct zone *zone; + struct page *page; + struct folio *folio; + unsigned long pfn, max_zone_pfn; + unsigned long total = 0, split = 0; + + pr_debug("Split all THPs\n"); + for_each_zone(zone) { + if (!managed_zone(zone)) + continue; + max_zone_pfn = zone_end_pfn(zone); + for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { + int nr_pages; + + page = pfn_to_online_page(pfn); + if (!page || PageTail(page)) + continue; + folio = page_folio(page); + if (!folio_try_get(folio)) + continue; + + if (unlikely(page_folio(page) != folio)) + goto next; + + if (zone != folio_zone(folio)) + goto next; + + if (!folio_test_large(folio) + || folio_test_hugetlb(folio) + || !folio_test_lru(folio)) + goto next; + + total++; + folio_lock(folio); + nr_pages = folio_nr_pages(folio); + if (!split_folio(folio)) + split++; + pfn += nr_pages - 1; + folio_unlock(folio); +next: + folio_put(folio); + cond_resched(); + } + } + + pr_debug("%lu of %lu THP split\n", split, total); +} + +static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) +{ + if (vma_is_dax(vma)) + return true; + if (vma_is_special_huge(vma)) + return true; + if (vma_test(vma, VMA_IO_BIT)) + return true; + if (is_vm_hugetlb_page(vma)) + return true; + + return false; +} + +static int split_huge_pages_pid(int pid, unsigned long vaddr_start, + unsigned long vaddr_end, unsigned int new_order, + long in_folio_offset) +{ + int ret = 0; + struct task_struct *task; + struct mm_struct *mm; + unsigned long total = 0, split = 0; + unsigned long addr; + + vaddr_start &= PAGE_MASK; + vaddr_end &= PAGE_MASK; + + task = find_get_task_by_vpid(pid); + if (!task) { + ret = -ESRCH; + goto out; + } + + /* Find the mm_struct */ + mm = get_task_mm(task); + put_task_struct(task); + + if (!mm) { + ret = -EINVAL; + goto out; + } + + pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx], new_order: %u, in_folio_offset: %ld\n", + pid, vaddr_start, vaddr_end, new_order, in_folio_offset); + + mmap_read_lock(mm); + /* + * always increase addr by PAGE_SIZE, since we could have a PTE page + * table filled with PTE-mapped THPs, each of which is distinct. + */ + for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { + struct vm_area_struct *vma = vma_lookup(mm, addr); + struct folio_walk fw; + struct folio *folio; + struct address_space *mapping; + unsigned int target_order = new_order; + + if (!vma) + break; + + /* skip special VMA and hugetlb VMA */ + if (vma_not_suitable_for_thp_split(vma)) { + addr = vma->vm_end; + continue; + } + + folio = folio_walk_start(&fw, vma, addr, 0); + if (!folio) + continue; + + if (!is_transparent_hugepage(folio)) + goto next; + + if (!folio_test_anon(folio)) { + mapping = folio->mapping; + target_order = max(new_order, + mapping_min_folio_order(mapping)); + } + + if (target_order >= folio_order(folio)) + goto next; + + total++; + /* + * For folios with private, split_huge_page_to_list_to_order() + * will try to drop it before split and then check if the folio + * can be split or not. So skip the check here. + */ + if (!folio_test_private(folio) && + folio_expected_ref_count(folio) != folio_ref_count(folio)) + goto next; + + if (!folio_trylock(folio)) + goto next; + folio_get(folio); + folio_walk_end(&fw, vma); + + if (!folio_test_anon(folio) && folio->mapping != mapping) + goto unlock; + + if (in_folio_offset < 0 || + in_folio_offset >= folio_nr_pages(folio)) { + if (!split_folio_to_order(folio, target_order)) + split++; + } else { + struct page *split_at = folio_page(folio, + in_folio_offset); + if (!folio_split(folio, target_order, split_at, NULL)) + split++; + } + +unlock: + + folio_unlock(folio); + folio_put(folio); + + cond_resched(); + continue; +next: + folio_walk_end(&fw, vma); + cond_resched(); + } + mmap_read_unlock(mm); + mmput(mm); + + pr_debug("%lu of %lu THP split\n", split, total); + +out: + return ret; +} + +static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, + pgoff_t off_end, unsigned int new_order, + long in_folio_offset) +{ + struct file *candidate; + struct address_space *mapping; + pgoff_t index; + int nr_pages = 1; + unsigned long total = 0, split = 0; + unsigned int min_order; + unsigned int target_order; + + CLASS(filename_kernel, file)(file_path); + candidate = file_open_name(file, O_RDONLY, 0); + if (IS_ERR(candidate)) + return -EINVAL; + + pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx], new_order: %u, in_folio_offset: %ld\n", + file_path, off_start, off_end, new_order, in_folio_offset); + + mapping = candidate->f_mapping; + min_order = mapping_min_folio_order(mapping); + target_order = max(new_order, min_order); + + for (index = off_start; index < off_end; index += nr_pages) { + struct folio *folio = filemap_get_folio(mapping, index); + + nr_pages = 1; + if (IS_ERR(folio)) + continue; + + if (!folio_test_large(folio)) + goto next; + + total++; + nr_pages = folio_nr_pages(folio); + + if (target_order >= folio_order(folio)) + goto next; + + if (!folio_trylock(folio)) + goto next; + + if (folio->mapping != mapping) + goto unlock; + + if (in_folio_offset < 0 || in_folio_offset >= nr_pages) { + if (!split_folio_to_order(folio, target_order)) + split++; + } else { + struct page *split_at = folio_page(folio, + in_folio_offset); + if (!folio_split(folio, target_order, split_at, NULL)) + split++; + } + +unlock: + folio_unlock(folio); +next: + folio_put(folio); + cond_resched(); + } + + filp_close(candidate, NULL); + pr_debug("%lu of %lu file-backed THP split\n", split, total); + return 0; +} + +#define MAX_INPUT_BUF_SZ 255 + +static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppops) +{ + static DEFINE_MUTEX(split_debug_mutex); + ssize_t ret; + /* + * hold pid, start_vaddr, end_vaddr, new_order or + * file_path, off_start, off_end, new_order + */ + char input_buf[MAX_INPUT_BUF_SZ]; + int pid; + unsigned long vaddr_start, vaddr_end; + unsigned int new_order = 0; + long in_folio_offset = -1; + + ret = mutex_lock_interruptible(&split_debug_mutex); + if (ret) + return ret; + + ret = -EFAULT; + + memset(input_buf, 0, MAX_INPUT_BUF_SZ); + if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) + goto out; + + input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; + + if (input_buf[0] == '/') { + char *tok; + char *tok_buf = input_buf; + char file_path[MAX_INPUT_BUF_SZ]; + pgoff_t off_start = 0, off_end = 0; + size_t input_len = strlen(input_buf); + + tok = strsep(&tok_buf, ","); + if (tok && tok_buf) { + strscpy(file_path, tok); + } else { + ret = -EINVAL; + goto out; + } + + ret = sscanf(tok_buf, "0x%lx,0x%lx,%d,%ld", &off_start, &off_end, + &new_order, &in_folio_offset); + if (ret != 2 && ret != 3 && ret != 4) { + ret = -EINVAL; + goto out; + } + ret = split_huge_pages_in_file(file_path, off_start, off_end, + new_order, in_folio_offset); + if (!ret) + ret = input_len; + + goto out; + } + + ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d,%ld", &pid, &vaddr_start, + &vaddr_end, &new_order, &in_folio_offset); + if (ret == 1 && pid == 1) { + split_huge_pages_all(); + ret = strlen(input_buf); + goto out; + } else if (ret != 3 && ret != 4 && ret != 5) { + ret = -EINVAL; + goto out; + } + + ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order, + in_folio_offset); + if (!ret) + ret = strlen(input_buf); +out: + mutex_unlock(&split_debug_mutex); + return ret; + +} + +static const struct file_operations split_huge_pages_fops = { + .owner = THIS_MODULE, + .write = split_huge_pages_write, +}; + +static int __init split_huge_pages_debugfs(void) +{ + debugfs_create_file("split_huge_pages", 0200, NULL, NULL, + &split_huge_pages_fops); + return 0; +} +late_initcall(split_huge_pages_debugfs); +#endif + +#ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES +int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, + struct page *page) +{ + struct folio *folio = page_folio(page); + struct vm_area_struct *vma = pvmw->vma; + struct mm_struct *mm = vma->vm_mm; + unsigned long address = pvmw->address; + bool anon_exclusive, present, writable, softdirty, uffd_wp; + pmd_t pmdval; + swp_entry_t entry; + pmd_t pmdswp; + + if (!(pvmw->pmd && !pvmw->pte)) + return 0; + + present = pmd_present(*pvmw->pmd); + if (likely(present)) { + flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); + + pmdval = pmdp_invalidate(vma, address, pvmw->pmd); + + writable = pmd_write(pmdval); + softdirty = pmd_soft_dirty(pmdval); + uffd_wp = pmd_uffd(pmdval); + } else { + softleaf_t old_entry; + + pmdval = pmdp_huge_get_and_clear(vma->vm_mm, address, pvmw->pmd); + old_entry = softleaf_from_pmd(pmdval); + + writable = softleaf_is_device_private_write(old_entry); + softdirty = pmd_swp_soft_dirty(pmdval); + uffd_wp = pmd_swp_uffd(pmdval); + } + + /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ + anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); + if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { + set_pmd_at(mm, address, pvmw->pmd, pmdval); + return -EBUSY; + } + + /* Determine type of migration entry. */ + if (writable) + entry = make_writable_migration_entry(page_to_pfn(page)); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); + else + entry = make_readable_migration_entry(page_to_pfn(page)); + + /* Set A/D bits as necessary. */ + if (present && pmd_young(pmdval)) + entry = make_migration_entry_young(entry); + if (present && pmd_dirty(pmdval)) { + folio_mark_dirty(folio); + entry = make_migration_entry_dirty(entry); + } + + /* Set PMD. */ + pmdswp = softleaf_to_pmd(entry); + if (softdirty) + pmdswp = pmd_swp_mksoft_dirty(pmdswp); + if (uffd_wp) + pmdswp = pmd_swp_mkuffd(pmdswp); + set_pmd_at(mm, address, pvmw->pmd, pmdswp); + + /* Migration entry installed: cleanup rmap, folio. */ + folio_remove_rmap_pmd(folio, page, vma); + folio_put(folio); + trace_set_migration_pmd(address, pmd_val(pmdswp)); + + return 0; +} + +void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) +{ + struct folio *folio = page_folio(new); + struct vm_area_struct *vma = pvmw->vma; + struct mm_struct *mm = vma->vm_mm; + unsigned long address = pvmw->address; + unsigned long haddr = address & HPAGE_PMD_MASK; + pmd_t pmde; + softleaf_t entry; + + if (!(pvmw->pmd && !pvmw->pte)) + return; + + entry = softleaf_from_pmd(*pvmw->pmd); + folio_get(folio); + pmde = folio_mk_pmd(folio, READ_ONCE(vma->vm_page_prot)); + + if (pmd_swp_soft_dirty(*pvmw->pmd)) + pmde = pmd_mksoft_dirty(pmde); + if (softleaf_is_migration_write(entry)) + pmde = pmd_mkwrite(pmde, vma); + if (pmd_swp_uffd(*pvmw->pmd)) + pmde = pmd_mkuffd(pmde); + + /* See do_swap_page(): restore PAGE_NONE for RWP */ + if (pmd_swp_uffd(*pvmw->pmd) && userfaultfd_rwp(vma)) + pmde = pmd_modify(pmde, PAGE_NONE); + + if (!softleaf_is_migration_young(entry)) + pmde = pmd_mkold(pmde); + /* NOTE: this may contain setting soft-dirty on some archs */ + if (folio_test_dirty(folio) && softleaf_is_migration_dirty(entry)) + pmde = pmd_mkdirty(pmde); + + if (folio_is_device_private(folio)) { + swp_entry_t entry; + + if (pmd_write(pmde)) + entry = make_writable_device_private_entry( + page_to_pfn(new)); + else + entry = make_readable_device_private_entry( + page_to_pfn(new)); + pmde = softleaf_to_pmd(entry); + + if (pmd_swp_soft_dirty(*pvmw->pmd)) + pmde = pmd_swp_mksoft_dirty(pmde); + if (pmd_swp_uffd(*pvmw->pmd)) + pmde = pmd_swp_mkuffd(pmde); + } + + if (folio_test_anon(folio)) { + rmap_t rmap_flags = RMAP_NONE; + + if (!softleaf_is_migration_read(entry)) + rmap_flags |= RMAP_EXCLUSIVE; + + folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); + } else { + folio_add_file_rmap_pmd(folio, new, vma); + } + VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new)); + set_pmd_at(mm, haddr, pvmw->pmd, pmde); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache_pmd(vma, address, pvmw->pmd); + trace_remove_migration_pmd(address, pmd_val(pmde)); +} +#endif |