| Quellcodebibliothek Statistik Leitseite products/Sources/formale Sprachen/C/Linux/mm/ (Linux Kernel Version 6.17.9©) Datei vom 24.10.2025 mit Größe 127 kB |
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Quelle huge_memory.c Sprache: C |
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// 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/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_tag.h> #include <linux/pagewalk.h> #include <asm/tlb.h> #include <asm/pgalloc.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 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; static atomic_t huge_zero_refcount; struct folio *huge_zero_folio __read_mostly; unsigned long huge_zero_pfn __read_mostly = ~0UL; 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 (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) return false; if (!vma->vm_file) return false; inode = file_inode(vma->vm_file); return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); } unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, vm_flags_t vm_flags, unsigned long tva_flags, unsigned long orders) { bool smaps = tva_flags & TVA_SMAPS; bool in_pf = tva_flags & TVA_IN_PF; bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS; 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_special_huge(vma)) supported_orders = THP_ORDERS_ALL_SPECIAL; 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)) 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->vm_pgoff, 0, !enforce_sysfs); if (!vma_is_anonymous(vma)) { /* * Enforce sysfs THP requirements as necessary. Anonymous vmas * were already handled in thp_vma_allowable_orders(). */ if (enforce_sysfs && (!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 bool get_huge_zero_page(void) { struct folio *zero_folio; retry: if (likely(atomic_inc_not_zero(&huge_zero_refcount))) return true; zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, HPAGE_PMD_ORDER); if (!zero_folio) { count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); return false; } /* Ensure zero folio won't have large_rmappable flag set. */ folio_clear_large_rmappable(zero_folio); preempt_disable(); if (cmpxchg(&huge_zero_folio, NULL, zero_folio)) { preempt_enable(); folio_put(zero_folio); goto retry; } WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); /* We take additional reference here. It will be put back by shrinker */ atomic_set(&huge_zero_refcount, 2); preempt_enable(); count_vm_event(THP_ZERO_PAGE_ALLOC); return true; } static void put_huge_zero_page(void) { /* * Counter should never go to zero here. Only shrinker can put * last reference. */ BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); } struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) { if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) return READ_ONCE(huge_zero_folio); if (!get_huge_zero_page()) return NULL; if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) put_huge_zero_page(); return READ_ONCE(huge_zero_folio); } void mm_put_huge_zero_folio(struct mm_struct *mm) { if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) put_huge_zero_page(); } static unsigned long shrink_huge_zero_page_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_page_scan(struct shrinker *shrink, struct shrink_control *sc) { if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { struct folio *zero_folio = xchg(&huge_zero_folio, NULL); BUG_ON(zero_folio == NULL); WRITE_ONCE(huge_zero_pfn, ~0UL); folio_put(zero_folio); return HPAGE_PMD_NR; } return 0; } static struct shrinker *huge_zero_page_shrinker; #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); } static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { ssize_t ret = count; if (sysfs_streq(buf, "always")) { clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "never")) { clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); } else ret = -EINVAL; if (ret > 0) { int err = start_stop_khugepaged(); if (err) ret = err; } return ret; } 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; } static ssize_t defrag_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { const char *output; if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) output = "[always] defer defer+madvise madvise never"; else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) output = "always [defer] defer+madvise madvise never"; else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) output = "always defer [defer+madvise] madvise never"; else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) output = "always defer defer+madvise [madvise] never"; else output = "always defer defer+madvise madvise [never]"; return sysfs_emit(buf, "%s\n", output); } static ssize_t defrag_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { if (sysfs_streq(buf, "always")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "defer+madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "defer")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "madvise")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); } else if (sysfs_streq(buf, "never")) { clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); } else return -EINVAL; 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 ssize_t anon_enabled_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { int order = to_thpsize(kobj)->order; ssize_t ret = count; if (sysfs_streq(buf, "always")) { spin_lock(&huge_anon_orders_lock); clear_bit(order, &huge_anon_orders_inherit); clear_bit(order, &huge_anon_orders_madvise); set_bit(order, &huge_anon_orders_always); spin_unlock(&huge_anon_orders_lock); } else if (sysfs_streq(buf, "inherit")) { spin_lock(&huge_anon_orders_lock); clear_bit(order, &huge_anon_orders_always); clear_bit(order, &huge_anon_orders_madvise); set_bit(order, &huge_anon_orders_inherit); spin_unlock(&huge_anon_orders_lock); } else if (sysfs_streq(buf, "madvise")) { spin_lock(&huge_anon_orders_lock); clear_bit(order, &huge_anon_orders_always); clear_bit(order, &huge_anon_orders_inherit); set_bit(order, &huge_anon_orders_madvise); spin_unlock(&huge_anon_orders_lock); } else if (sysfs_streq(buf, "never")) { spin_lock(&huge_anon_orders_lock); clear_bit(order, &huge_anon_orders_always); clear_bit(order, &huge_anon_orders_inherit); clear_bit(order, &huge_anon_orders_madvise); spin_unlock(&huge_anon_orders_lock); } else ret = -EINVAL; if (ret > 0) { int err; err = start_stop_khugepaged(); if (err) ret = err; } return ret; } 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_C 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_MAPPE 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, 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, 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(sizeof(*thpsize), GFP_KERNEL); if (!thpsize) goto err; thpsize->order = order; ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, "hugepages-%lukB", size); if (ret) { kfree(thpsize); goto err; } 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 */ static int __init thp_shrinker_init(void) { huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero"); if (!huge_zero_page_shrinker) return -ENOMEM; deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | SHRINKER_NONSLAB, "thp-deferred_split"); if (!deferred_split_shrinker) { shrinker_free(huge_zero_page_shrinker); return -ENOMEM; } huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; shrinker_register(huge_zero_page_shrinker); deferred_split_shrinker->count_objects = deferred_split_count; deferred_split_shrinker->scan_objects = deferred_split_scan; shrinker_register(deferred_split_shrinker); return 0; } static void __init thp_shrinker_exit(void) { shrinker_free(huge_zero_page_shrinker); shrinker_free(deferred_split_shrinker); } 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() < (512 << (20 - PAGE_SHIFT))) { 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; } #ifdef CONFIG_MEMCG static inline struct deferred_split *get_deferred_split_queue(struct folio *folio) { struct mem_cgroup *memcg = folio_memcg(folio); struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); if (memcg) return &memcg->deferred_split_queue; else return &pgdat->deferred_split_queue; } #else static inline struct deferred_split *get_deferred_split_queue(struct folio *folio) { struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); return &pgdat->deferred_split_queue; } #endif 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, vm_flags_t vm_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_vmflags(current->mm, filp, addr, len_pad, off >> PAGE_SHIFT, flags, vm_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 (test_bit(MMF_TOPDOWN, ¤t->mm->flags) && !off_sub) return ret + size; ret += off_sub; return ret; } unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) { unsigned long ret; loff_t off = (loff_t)pgoff << PAGE_SHIFT; ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags); if (ret) return ret; return mm_get_unmapped_area_vmflags(current->mm, filp, addr, len, pgoff, flags, vm_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_vmflags(filp, addr, len, pgoff, flags, 0); } 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; } 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; } static void map_anon_folio_pmd(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); 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(folio, vmf->pmd, vma, haddr); mm_inc_nr_ptes(vma->vm_mm); deferred_split_folio(folio, false); 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; } /* * 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); 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 int insert_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, struct folio_or_pfn fop, pgprot_t prot, bool write, pgtable_t pgtable) { struct mm_struct *mm = vma->vm_mm; pmd_t entry; lockdep_assert_held(pmd_lockptr(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)); return -EEXIST; } 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); } return -EEXIST; } if (fop.is_folio) { entry = folio_mk_pmd(fop.folio, vma->vm_page_prot); 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); } set_pmd_at(mm, addr, pmd, entry); update_mmu_cache_pmd(vma, addr, pmd); return 0; } /** * 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, }; pgtable_t pgtable = NULL; spinlock_t *ptl; int error; /* * 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)); 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; } pfnmap_setup_cachemode_pfn(pfn, &pgprot); ptl = pmd_lock(vma->vm_mm, vmf->pmd); error = insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write, pgtable); spin_unlock(ptl); if (error && pgtable) pte_free(vma->vm_mm, pgtable); return VM_FAULT_NOPAGE; } 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 mm_struct *mm = vma->vm_mm; struct folio_or_pfn fop = { .folio = folio, .is_folio = true, }; spinlock_t *ptl; pgtable_t pgtable = NULL; int error; if (addr < vma->vm_start || addr >= vma->vm_end) return VM_FAULT_SIGBUS; if (WARN_ON_ONCE(folio_order(folio) != PMD_ORDER)) 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, vmf->pmd); error = insert_pmd(vma, addr, vmf->pmd, fop, vma->vm_page_prot, write, pgtable); spin_unlock(ptl); if (error && pgtable) pte_free(mm, pgtable); return VM_FAULT_NOPAGE; } 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 void 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; pud_t entry; 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)) return; 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); } return; } 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); } /** * 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, }; spinlock_t *ptl; /* * 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)); if (addr < vma->vm_start || addr >= vma->vm_end) return VM_FAULT_SIGBUS; pfnmap_setup_cachemode_pfn(pfn, &pgprot); ptl = pud_lock(vma->vm_mm, vmf->pud); insert_pud(vma, addr, vmf->pud, fop, pgprot, write); spin_unlock(ptl); return VM_FAULT_NOPAGE; } 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; pud_t *pud = vmf->pud; struct mm_struct *mm = vma->vm_mm; struct folio_or_pfn fop = { .folio = folio, .is_folio = true, }; spinlock_t *ptl; if (addr < vma->vm_start || addr >= vma->vm_end) return VM_FAULT_SIGBUS; if (WARN_ON_ONCE(folio_order(folio) != PUD_ORDER)) return VM_FAULT_SIGBUS; ptl = pud_lock(mm, pud); insert_pud(vma, addr, vmf->pud, fop, vma->vm_page_prot, write); spin_unlock(ptl); return VM_FAULT_NOPAGE; } EXPORT_SYMBOL_GPL(vmf_insert_folio_pud); #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ void touch_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, bool write) { pmd_t _pmd; _pmd = pmd_mkyoung(*pmd); if (write) _pmd = pmd_mkdirty(_pmd); if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, pmd, _pmd, write)) update_mmu_cache_pmd(vma, addr, 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))) { 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; #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION if (unlikely(is_swap_pmd(pmd))) { swp_entry_t entry = pmd_to_swp_entry(pmd); VM_BUG_ON(!is_pmd_migration_entry(pmd)); if (!is_readable_migration_entry(entry)) { entry = make_readable_migration_entry( swp_offset(entry)); pmd = swp_entry_to_pmd(entry); if (pmd_swp_soft_dirty(*src_pmd)) pmd = pmd_swp_mksoft_dirty(pmd); if (pmd_swp_uffd_wp(*src_pmd)) pmd = pmd_swp_mkuffd_wp(pmd); set_pmd_at(src_mm, addr, src_pmd, pmd); } 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_wp(dst_vma)) pmd = pmd_swp_clear_uffd_wp(pmd); set_pmd_at(dst_mm, addr, dst_pmd, pmd); ret = 0; goto out_unlock; } #endif 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); pmdp_set_wrprotect(src_mm, addr, src_pmd); if (!userfaultfd_wp(dst_vma)) pmd = pmd_clear_uffd_wp(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 */ void huge_pmd_set_accessed(struct vm_fault *vmf) { bool write = vmf->flags & FAULT_FLAG_WRITE; vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) goto unlock; touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); unlock: spin_unlock(vmf->ptl); } 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(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); } /* 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_BUG_ON(thp_migration_supported() && !is_pmd_migration_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); } int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr) { pmd_t orig_pmd; spinlock_t *ptl; tlb_change_page_size(tlb, HPAGE_PMD_SIZE); ptl = __pmd_trans_huge_lock(pmd, vma); if (!ptl) return 0; /* * 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); if (!vma_is_dax(vma) && vma_is_special_huge(vma)) { if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); } else if (is_huge_zero_pmd(orig_pmd)) { if (!vma_is_dax(vma) || arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); } else { struct folio *folio = NULL; int flush_needed = 1; if (pmd_present(orig_pmd)) { struct page *page = pmd_page(orig_pmd); folio = page_folio(page); folio_remove_rmap_pmd(folio, page, vma); WARN_ON_ONCE(folio_mapcount(folio) < 0); VM_BUG_ON_PAGE(!PageHead(page), page); } else if (thp_migration_supported()) { swp_entry_t entry; VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); entry = pmd_to_swp_entry(orig_pmd); folio = pfn_swap_entry_folio(entry); flush_needed = 0; } else WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); if (folio_test_anon(folio)) { zap_deposited_table(tlb->mm, pmd); add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); } else { if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); add_mm_counter(tlb->mm, mm_counter_file(folio), -HPAGE_PMD_NR); /* * Use flush_needed to indicate whether the PMD entry * is present, instead of checking pmd_present() again. */ if (flush_needed && pmd_young(orig_pmd) && likely(vma_has_recency(vma))) folio_mark_accessed(folio); } spin_unlock(ptl); if (flush_needed) tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); } return 1; } #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) { #ifdef CONFIG_MEM_SOFT_DIRTY if (unlikely(is_pmd_migration_entry(pmd))) pmd = pmd_swp_mksoft_dirty(pmd); else if (pmd_present(pmd)) pmd = pmd_mksoft_dirty(pmd); #endif return pmd; } static pmd_t clear_uffd_wp_pmd(pmd_t pmd) { if (pmd_present(pmd)) pmd = pmd_clear_uffd_wp(pmd); else if (is_swap_pmd(pmd)) pmd = pmd_swp_clear_uffd_wp(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)) 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; } /* * 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_wp = cp_flags & MM_CP_UFFD_WP; bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_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; #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION if (is_swap_pmd(*pmd)) { swp_entry_t entry = pmd_to_swp_entry(*pmd); struct folio *folio = pfn_swap_entry_folio(entry); pmd_t newpmd; VM_BUG_ON(!is_pmd_migration_entry(*pmd)); if (is_writable_migration_entry(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 = swp_entry_to_pmd(entry); if (pmd_swp_soft_dirty(*pmd)) newpmd = pmd_swp_mksoft_dirty(newpmd); } else { newpmd = *pmd; } if (uffd_wp) newpmd = pmd_swp_mkuffd_wp(newpmd); else if (uffd_wp_resolve) newpmd = pmd_swp_clear_uffd_wp(newpmd); if (!pmd_same(*pmd, newpmd)) set_pmd_at(mm, addr, pmd, newpmd); goto unlock; } #endif if (prot_numa) { struct folio *folio; bool toptier; /* * 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 (pmd_protnone(*pmd)) goto unlock; folio = pmd_folio(*pmd); toptier = node_is_toptier(folio_nid(folio)); /* * Skip scanning top tier node if normal numa * balancing is disabled */ if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && toptier) goto unlock; if (folio_use_access_time(folio)) folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); } /* * 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_wp) entry = pmd_mkuffd_wp(entry); else if (uffd_wp_resolve) /* * Leave the write bit to be handled by PF interrupt * handler, then things like COW could be properly * handled. */ entry = pmd_clear_uffd_wp(entry); /* 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 only works with anonymous, while we * don't have anonymous PUDs yet. */ if (WARN_ON_ONCE(cp_flags & MM_CP_UFFD_WP_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_p 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; struct anon_vma *src_anon_vma; 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_MAS 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 (is_pmd_migration_entry(src_pmdval)) { pmd_migration_entry_wait(mm, &src_pmdval); 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); /* * split_huge_page walks the anon_vma chain without the page * lock. Serialize against it with the anon_vma lock, the page * lock is not enough. */ src_anon_vma = folio_get_anon_vma(src_folio); if (!src_anon_vma) { err = -EAGAIN; goto unlock_folio; } anon_vma_lock_write(src_anon_vma); } else src_anon_vma = NULL; 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 = folio_mk_pmd(src_folio, dst_vma->vm_page_prot); } 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); if (src_anon_vma) { anon_vma_unlock_write(src_anon_vma); put_anon_vma(src_anon_vma); } unlock_folio: /* 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(is_swap_pmd(*pmd) || pmd_trans_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_dax(vma) && 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); folio_put(folio); add_mm_counter(vma->vm_mm, mm_counter_file(folio), -HPAGE_PUD_NR); } 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(my_zero_pfn(addr), vma->vm_page_prot); entry = pte_mkspecial(entry); if (pmd_uffd_wp(old_pmd)) entry = pte_mkuffd_wp(entry); 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 young, write, soft_dirty, pmd_migration = false, uffd_wp = 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_BUG_ON(!is_pmd_migration_entry(*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_dax(vma) && vma_is_special_huge(vma)) return; if (unlikely(is_pmd_migration_entry(old_pmd))) { swp_entry_t entry; entry = pmd_to_swp_entry(old_pmd); folio = pfn_swap_entry_folio(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); folio_put(folio); } 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); } pmd_migration = is_pmd_migration_entry(*pmd); if (unlikely(pmd_migration)) { swp_entry_t entry; old_pmd = *pmd; entry = pmd_to_swp_entry(old_pmd); page = pfn_swap_entry_to_page(entry); write = is_writable_migration_entry(entry); if (PageAnon(page)) anon_exclusive = is_readable_exclusive_migration_entry(entry); young = is_migration_entry_young(entry); dirty = is_migration_entry_dirty(entry); soft_dirty = pmd_swp_soft_dirty(old_pmd); uffd_wp = pmd_swp_uffd_wp(old_pmd); } 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_wp(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_migration) { for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { pte_t entry; swp_entry_t swp_entry; 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_wp(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_wp(entry); 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_migration) 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) || is_pmd_migration_entry(*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 ad { /* * 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, RMP_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 (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); } } /* Racy check whether the huge page can be split */ bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins) { int extra_pins; /* Additional pins from page cache */ if (folio_test_anon(folio)) extra_pins = folio_test_swapcache(folio) ? folio_nr_pages(folio) : 0; else extra_pins = folio_nr_pages(folio); if (pextra_pins) *pextra_pins = extra_pins; return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - caller_pins; } 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 &= ~PAGE_FLAGS_CHECK_AT_PREP; new_folio->flags |= (folio->flags & ((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) | LRU_GEN_MASK | LRU_REFS_MASK)); if (handle_hwpoison && page_range_has_hwpoisoned(new_head, new_nr_pages)) folio_set_has_hwpoisoned(new_folio); new_folio->mapping = folio->mapping; new_folio->index = folio->index + i; /* * page->private should not be set in tail pages. Fix up and warn once * if private is unexpectedly set. */ if (unlikely(new_folio->private)) { VM_WARN_ON_ONCE_PAGE(true, new_head); new_folio->private = NULL; } 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); } 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); } /* * It splits an unmapped @folio to lower order smaller folios in two ways. * @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 * @uniform_split: 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 * uniform_split is true. * 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 @page's order becomes @new_order. This is done when * uniform_split is false. * * The high level flow for these two methods are: * 1. uniform split: a single __split_folio_to_order() is called to split the * @folio into @new_order, then we traverse all the resulting folios one by * one in PFN ascending order and perform stats, unfreeze, adding to list, * and file mapping index operations. * 2. non-uniform split: in general, folio_order - @new_order calls to * __split_folio_to_order() are made in a for loop to split the @folio * to one lower order at a time. The resulting small folios are processed * like what is done during the traversal in 1, except the one containing * @page, which is split in next for loop. * * After splitting, the caller's folio reference will be transferred to the * folio containing @page. The caller needs to unlock and/or free after-split * folios if necessary. * * For !uniform_split, when -ENOMEM is returned, the original folio might be * split. The caller needs to check the input folio. */ static int __split_unmapped_folio(struct folio *folio, int new_order, struct page *split_at, struct xa_state *xas, struct address_space *mapping, bool uniform_split) { int order = folio_order(folio); int start_order = uniform_split ? new_order : order - 1; bool stop_split = false; struct folio *next; int split_order; int ret = 0; if (folio_test_anon(folio)) mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); /* * 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 && !stop_split; split_order--) { struct folio *end_folio = folio_next(folio); int old_order = folio_order(folio); struct folio *new_folio; /* order-1 anonymous folio is not supported */ if (folio_test_anon(folio) && split_order == 1) continue; if (uniform_split && split_order != new_order) 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. */ if (uniform_split) xas_split(xas, folio, old_order); else { xas_set_order(xas, folio->index, split_order); xas_try_split(xas, folio, old_order); if (xas_error(xas)) { ret = xas_error(xas); stop_split = true; } } } if (!stop_split) { 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); } /* * Iterate through after-split folios and update folio stats. * But in buddy allocator like split, the folio * containing the specified page is skipped until its order * is new_order, since the folio will be worked on in next * iteration. */ for (new_folio = folio; new_folio != end_folio; new_folio = next) { next = folio_next(new_folio); /* * for buddy allocator like split, new_folio containing * @split_at page could be split again, thus do not * change stats yet. Wait until new_folio's order is * @new_order or stop_split is set to true by the above * xas_split() failure. */ if (new_folio == page_folio(split_at)) { folio = new_folio; if (split_order != new_order && !stop_split) continue; } if (folio_test_anon(new_folio)) mod_mthp_stat(folio_order(new_folio), MTHP_STAT_NR_ANON, 1); } } return ret; } bool non_uniform_split_supported(struct folio *folio, unsigned int new_order, bool warns) { if (folio_test_anon(folio)) { /* order-1 is not supported for anonymous THP. */ VM_WARN_ONCE(warns && new_order == 1, "Cannot split to order-1 folio"); if (new_order == 1) return false; } else if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !mapping_large_folio_support(folio->mapping)) { /* * No split if the file system does not support large folio. * Note that we might still have THPs in such mappings due to * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping * does not actually support large folios properly. */ VM_WARN_ONCE(warns, "Cannot split file folio to non-0 order"); return false; } /* Only swapping a whole PMD-mapped folio is supported */ if (folio_test_swapcache(folio)) { VM_WARN_ONCE(warns, "Cannot split swapcache folio to non-0 order"); return false; } return true; } /* See comments in non_uniform_split_supported() */ bool uniform_split_supported(struct folio *folio, unsigned int new_order, bool warns) { if (folio_test_anon(folio)) { VM_WARN_ONCE(warns && new_order == 1, "Cannot split to order-1 folio"); if (new_order == 1) return false; } else if (new_order) { if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !mapping_large_folio_support(folio->mapping)) { VM_WARN_ONCE(warns, "Cannot split file folio to non-0 order"); return false; } } if (new_order && folio_test_swapcache(folio)) { VM_WARN_ONCE(warns, "Cannot split swapcache folio to non-0 order"); return false; } return true; } /* * __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 * @uniform_split: 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, bool uniform_split) { struct deferred_split *ds_queue = get_deferred_split_queue(folio); 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 order = folio_order(folio); struct folio *new_folio, *next; int nr_shmem_dropped = 0; int remap_flags = 0; int extra_pins, ret; pgoff_t end; bool is_hzp; 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)) return -EINVAL; if (new_order >= folio_order(folio)) return -EINVAL; if (uniform_split && !uniform_split_supported(folio, new_order, true)) return -EINVAL; if (!uniform_split && !non_uniform_split_supported(folio, new_order, true)) return -EINVAL; is_hzp = is_huge_zero_folio(folio); if (is_hzp) { pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); return -EBUSY; } if (folio_test_writeback(folio)) return -EBUSY; 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; } mapping = NULL; anon_vma_lock_write(anon_vma); } else { unsigned int min_order; gfp_t gfp; mapping = folio->mapping; /* Truncated ? */ /* * TODO: add support for large shmem folio in swap cache. * When shmem is in swap cache, mapping is NULL and * folio_test_swapcache() is true. */ if (!mapping) { ret = -EBUSY; goto out; } min_order = mapping_min_folio_order(folio->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; } if (uniform_split) { xas_set_order(&xas, folio->index, new_order); xas_split_alloc(&xas, folio, folio_order(folio), 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 (!can_split_folio(folio, 1, &extra_pins)) { 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; } } /* Prevent deferred_split_scan() touching ->_refcount */ spin_lock(&ds_queue->split_queue_lock); if (folio_ref_freeze(folio, 1 + extra_pins)) { struct address_space *swap_cache = NULL; struct lruvec *lruvec; int expected_refs; if (folio_order(folio) > 1 && !list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; if (folio_test_partially_mapped(folio)) { folio_clear_partially_mapped(folio); mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); } /* * Reinitialize page_deferred_list after removing the * page from the split_queue, otherwise a subsequent * split will see list corruption when checking the * page_deferred_list. */ list_del_init(&folio->_deferred_list); } spin_unlock(&ds_queue->split_queue_lock); 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); filemap_nr_thps_dec(mapping); } } } if (folio_test_swapcache(folio)) { if (mapping) { VM_WARN_ON_ONCE_FOLIO(mapping, folio); ret = -EINVAL; goto fail; } swap_cache = swap_address_space(folio->swap); xa_lock(&swap_cache->i_pages); } /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ lruvec = folio_lruvec_lock(folio); ret = __split_unmapped_folio(folio, new_order, split_at, &xas, mapping, uniform_split); /* * 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); expected_refs = folio_expected_ref_count(new_folio) + 1; folio_ref_unfreeze(new_folio, expected_refs); lru_add_split_folio(folio, new_folio, lruvec, list); /* * Anonymous folio with swap cache. * NOTE: shmem in swap cache is not supported yet. */ if (swap_cache) { __xa_store(&swap_cache->i_pages, swap_cache_index(new_folio->swap), new_folio, 0); 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; } /* Drop folio beyond EOF: ->index >= end */ if (shmem_mapping(mapping)) 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); } /* * 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. */ expected_refs = folio_expected_ref_count(folio) + 1; folio_ref_unfreeze(folio, expected_refs); unlock_page_lruvec(lruvec); if (swap_cache) xa_unlock(&swap_cache->i_pages); } else { spin_unlock(&ds_queue->split_queue_lock); ret = -EAGAIN; } fail: if (mapping) xas_unlock(&xas); local_irq_enable(); if (nr_shmem_dropped) shmem_uncharge(mapping->host, nr_shmem_dropped); if (!ret && is_anon) remap_flags = RMP_USE_SHARED_ZEROPAGE; remap_page(folio, 1 << order, remap_flags); /* * 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 may be freed if there wasn't any mapping * like if add_to_swap() is running on a lru page that * had its mapping zapped. And freeing these pages * requires taking the lru_lock so we do the put_page * of the tail pages after the split is complete. */ 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 (order == HPAGE_PMD_ORDER) count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); count_mthp_stat(order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); 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, true); } /* * 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 * * return: 0: successful, <0 failed (if -ENOMEM is returned, @folio might be * split but not to @new_order, the caller needs to check) * * 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. */ 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, false); } int min_order_for_split(struct folio *folio) { if (folio_test_anon(folio)) return 0; if (!folio->mapping) { if (folio_test_pmd_mappable(folio)) count_vm_event(THP_SPLIT_PAGE_FAILED); return -EBUSY; } 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 split_queue_lock is held, a non-empty _deferred_list * might be in use on deferred_split_scan()'s unlocked on-stack list. * * If memory cgroups are enabled, split_queue_lock is in the mem_cgroup: it is * therefore important to unqueue deferred split before changing folio memcg. */ bool __folio_unqueue_deferred_split(struct folio *folio) { struct deferred_split *ds_queue; unsigned long flags; bool unqueued = false; WARN_ON_ONCE(folio_ref_count(folio)); WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg(folio)); ds_queue = get_deferred_split_queue(folio); spin_lock_irqsave(&ds_queue->split_queue_lock, flags); if (!list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; 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_del_init(&folio->_deferred_list); unqueued = true; } spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 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 deferred_split *ds_queue = get_deferred_split_queue(folio); #ifdef CONFIG_MEMCG struct mem_cgroup *memcg = folio_memcg(folio); #endif 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; spin_lock_irqsave(&ds_queue->split_queue_lock, 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); } if (list_empty(&folio->_deferred_list)) { list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); ds_queue->split_queue_len++; #ifdef CONFIG_MEMCG if (memcg) set_shrinker_bit(memcg, folio_nid(folio), deferred_split_shrinker->id); #endif } spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); } static unsigned long deferred_split_count(struct shrinker *shrink, struct shrink_control *sc) { struct pglist_data *pgdata = NODE_DATA(sc->nid); struct deferred_split *ds_queue = &pgdata->deferred_split_queue; #ifdef CONFIG_MEMCG if (sc->memcg) ds_queue = &sc->memcg->deferred_split_queue; #endif return READ_ONCE(ds_queue->split_queue_len); } 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 unsigned long deferred_split_scan(struct shrinker *shrink, struct shrink_control *sc) { struct pglist_data *pgdata = NODE_DATA(sc->nid); struct deferred_split *ds_queue = &pgdata->deferred_split_queue; unsigned long flags; LIST_HEAD(list); struct folio *folio, *next, *prev = NULL; int split = 0, removed = 0; #ifdef CONFIG_MEMCG if (sc->memcg) ds_queue = &sc->memcg->deferred_split_queue; #endif spin_lock_irqsave(&ds_queue->split_queue_lock, flags); /* Take pin on all head pages to avoid freeing them under us */ list_for_each_entry_safe(folio, next, &ds_queue->split_queue, _deferred_list) { if (folio_try_get(folio)) { list_move(&folio->_deferred_list, &list); } else { /* We lost race with folio_put() */ 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_del_init(&folio->_deferred_list); ds_queue->split_queue_len--; } if (!--sc->nr_to_scan) break; } spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); list_for_each_entry_safe(folio, next, &list, _deferred_list) { bool did_split = false; bool underused = false; if (!folio_test_partially_mapped(folio)) { underused = thp_underused(folio); if (!underused) goto next; } if (!folio_trylock(folio)) goto next; if (!split_folio(folio)) { did_split = true; if (underused) count_vm_event(THP_UNDERUSED_SPLIT_PAGE); split++; } folio_unlock(folio); next: /* * split_folio() removes folio from list on success. * Only add back to the queue if folio is partially mapped. * If thp_underused returns false, 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 already removed from list */ } else if (!folio_test_partially_mapped(folio)) { list_del_init(&folio->_deferred_list); removed++; } else { /* * That unlocked list_del_init() above would be unsafe, * unless its folio is separated from any earlier folios * left on the list (which may be concurrently unqueued) * by one safe folio with refcount still raised. */ swap(folio, prev); } if (folio) folio_put(folio); } spin_lock_irqsave(&ds_queue->split_queue_lock, flags); list_splice_tail(&list, &ds_queue->split_queue); ds_queue->split_queue_len -= removed; spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); if (prev) folio_put(prev); /* * Stop shrinker if we didn't split any page, but the queue is empty. * This can happen if pages were freed under us. */ if (!split && list_empty(&ds_queue->split_queue)) 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) { return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || is_vm_hugetlb_page(vma); } 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]\n", pid, vaddr_start, vaddr_end); 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) && !can_split_folio(folio, 0, NULL)) 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 filename *file; struct file *candidate; struct address_space *mapping; int ret = -EINVAL; pgoff_t index; int nr_pages = 1; unsigned long total = 0, split = 0; unsigned int min_order; unsigned int target_order; file = getname_kernel(file_path); if (IS_ERR(file)) return ret; candidate = file_open_name(file, O_RDONLY, 0); if (IS_ERR(candidate)) goto out; pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", file_path, off_start, off_end); 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); ret = 0; pr_debug("%lu of %lu file-backed THP split\n", split, total); out: putname(file); return ret; } #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_ENABLE_THP_MIGRATION 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; pmd_t pmdval; swp_entry_t entry; pmd_t pmdswp; if (!(pvmw->pmd && !pvmw->pte)) return 0; flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); pmdval = pmdp_invalidate(vma, address, pvmw->pmd); /* 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; } if (pmd_dirty(pmdval)) folio_mark_dirty(folio); if (pmd_write(pmdval)) 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)); if (pmd_young(pmdval)) entry = make_migration_entry_young(entry); if (pmd_dirty(pmdval)) entry = make_migration_entry_dirty(entry); pmdswp = swp_entry_to_pmd(entry); if (pmd_soft_dirty(pmdval)) pmdswp = pmd_swp_mksoft_dirty(pmdswp); if (pmd_uffd_wp(pmdval)) pmdswp = pmd_swp_mkuffd_wp(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); 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; swp_entry_t entry; if (!(pvmw->pmd && !pvmw->pte)) return; entry = pmd_to_swp_entry(*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 (is_writable_migration_entry(entry)) pmde = pmd_mkwrite(pmde, vma); if (pmd_swp_uffd_wp(*pvmw->pmd)) pmde = pmd_mkuffd_wp(pmde); if (!is_migration_entry_young(entry)) pmde = pmd_mkold(pmde); /* NOTE: this may contain setting soft-dirty on some archs */ if (folio_test_dirty(folio) && is_migration_entry_dirty(entry)) pmde = pmd_mkdirty(pmde); if (folio_test_anon(folio)) { rmap_t rmap_flags = RMAP_NONE; if (!is_readable_migration_entry(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
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2026-10-11