| // 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/coredump.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/dax.h> |
| #include <linux/khugepaged.h> |
| #include <linux/freezer.h> |
| #include <linux/pfn_t.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 <asm/tlb.h> |
| #include <asm/pgalloc.h> |
| #include "internal.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 atomic_t huge_zero_refcount; |
| struct page *huge_zero_page __read_mostly; |
| unsigned long huge_zero_pfn __read_mostly = ~0UL; |
| |
| static inline bool file_thp_enabled(struct vm_area_struct *vma) |
| { |
| return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file && |
| !inode_is_open_for_write(vma->vm_file->f_inode) && |
| (vma->vm_flags & VM_EXEC); |
| } |
| |
| bool transparent_hugepage_active(struct vm_area_struct *vma) |
| { |
| /* The addr is used to check if the vma size fits */ |
| unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; |
| |
| if (!transhuge_vma_suitable(vma, addr)) |
| return false; |
| if (vma_is_anonymous(vma)) |
| return __transparent_hugepage_enabled(vma); |
| if (vma_is_shmem(vma)) |
| return shmem_huge_enabled(vma); |
| if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) |
| return file_thp_enabled(vma); |
| |
| return false; |
| } |
| |
| static bool get_huge_zero_page(void) |
| { |
| struct page *zero_page; |
| retry: |
| if (likely(atomic_inc_not_zero(&huge_zero_refcount))) |
| return true; |
| |
| zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, |
| HPAGE_PMD_ORDER); |
| if (!zero_page) { |
| count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); |
| return false; |
| } |
| count_vm_event(THP_ZERO_PAGE_ALLOC); |
| preempt_disable(); |
| if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
| preempt_enable(); |
| __free_pages(zero_page, compound_order(zero_page)); |
| goto retry; |
| } |
| WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); |
| |
| /* We take additional reference here. It will be put back by shrinker */ |
| atomic_set(&huge_zero_refcount, 2); |
| preempt_enable(); |
| 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 page *mm_get_huge_zero_page(struct mm_struct *mm) |
| { |
| if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) |
| return READ_ONCE(huge_zero_page); |
| |
| 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_page); |
| } |
| |
| void mm_put_huge_zero_page(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 page *zero_page = xchg(&huge_zero_page, NULL); |
| BUG_ON(zero_page == NULL); |
| WRITE_ONCE(huge_zero_pfn, ~0UL); |
| __free_pages(zero_page, compound_order(zero_page)); |
| return HPAGE_PMD_NR; |
| } |
| |
| return 0; |
| } |
| |
| static struct shrinker huge_zero_page_shrinker = { |
| .count_objects = shrink_huge_zero_page_count, |
| .scan_objects = shrink_huge_zero_page_scan, |
| .seeks = DEFAULT_SEEKS, |
| }; |
| |
| #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(enabled, 0644, enabled_show, enabled_store); |
| |
| 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(defrag, 0644, defrag_show, defrag_store); |
| |
| 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(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); |
| |
| 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 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 |
| NULL, |
| }; |
| |
| static const struct attribute_group hugepage_attr_group = { |
| .attrs = hugepage_attr, |
| }; |
| |
| static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
| { |
| int err; |
| |
| *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; |
| } |
| |
| return 0; |
| |
| 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) |
| { |
| 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 hugepage_init(void) |
| { |
| int err; |
| struct kobject *hugepage_kobj; |
| |
| if (!has_transparent_hugepage()) { |
| /* |
| * Hardware doesn't support hugepages, hence disable |
| * DAX PMD support. |
| */ |
| transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; |
| return -EINVAL; |
| } |
| |
| /* |
| * hugepages can't be allocated by the buddy allocator |
| */ |
| MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); |
| /* |
| * we use page->mapping and page->index in second tail page |
| * as list_head: assuming THP order >= 2 |
| */ |
| MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); |
| |
| err = hugepage_init_sysfs(&hugepage_kobj); |
| if (err) |
| goto err_sysfs; |
| |
| err = khugepaged_init(); |
| if (err) |
| goto err_slab; |
| |
| err = register_shrinker(&huge_zero_page_shrinker); |
| if (err) |
| goto err_hzp_shrinker; |
| err = register_shrinker(&deferred_split_shrinker); |
| if (err) |
| goto err_split_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: |
| unregister_shrinker(&deferred_split_shrinker); |
| err_split_shrinker: |
| unregister_shrinker(&huge_zero_page_shrinker); |
| err_hzp_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); |
| |
| pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
| { |
| if (likely(vma->vm_flags & VM_WRITE)) |
| pmd = pmd_mkwrite(pmd); |
| return pmd; |
| } |
| |
| #ifdef CONFIG_MEMCG |
| static inline struct deferred_split *get_deferred_split_queue(struct page *page) |
| { |
| struct mem_cgroup *memcg = page_memcg(compound_head(page)); |
| struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); |
| |
| if (memcg) |
| return &memcg->deferred_split_queue; |
| else |
| return &pgdat->deferred_split_queue; |
| } |
| #else |
| static inline struct deferred_split *get_deferred_split_queue(struct page *page) |
| { |
| struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); |
| |
| return &pgdat->deferred_split_queue; |
| } |
| #endif |
| |
| void prep_transhuge_page(struct page *page) |
| { |
| /* |
| * we use page->mapping and page->indexlru in second tail page |
| * as list_head: assuming THP order >= 2 |
| */ |
| |
| INIT_LIST_HEAD(page_deferred_list(page)); |
| set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); |
| } |
| |
| bool is_transparent_hugepage(struct page *page) |
| { |
| if (!PageCompound(page)) |
| return false; |
| |
| page = compound_head(page); |
| return is_huge_zero_page(page) || |
| page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; |
| } |
| EXPORT_SYMBOL_GPL(is_transparent_hugepage); |
| |
| 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) |
| { |
| loff_t off_end = off + len; |
| loff_t off_align = round_up(off, size); |
| unsigned long len_pad, ret; |
| |
| 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 = current->mm->get_unmapped_area(filp, addr, len_pad, |
| off >> PAGE_SHIFT, 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; |
| |
| ret += (off - ret) & (size - 1); |
| return ret; |
| } |
| |
| unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, |
| unsigned long len, unsigned long pgoff, unsigned long flags) |
| { |
| unsigned long ret; |
| loff_t off = (loff_t)pgoff << PAGE_SHIFT; |
| |
| if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) |
| goto out; |
| |
| ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); |
| if (ret) |
| return ret; |
| out: |
| return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); |
| } |
| EXPORT_SYMBOL_GPL(thp_get_unmapped_area); |
| |
| static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, |
| struct page *page, gfp_t gfp) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| pgtable_t pgtable; |
| unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
| vm_fault_t ret = 0; |
| |
| VM_BUG_ON_PAGE(!PageCompound(page), page); |
| |
| if (mem_cgroup_charge(page, vma->vm_mm, gfp)) { |
| put_page(page); |
| count_vm_event(THP_FAULT_FALLBACK); |
| count_vm_event(THP_FAULT_FALLBACK_CHARGE); |
| return VM_FAULT_FALLBACK; |
| } |
| cgroup_throttle_swaprate(page, gfp); |
| |
| pgtable = pte_alloc_one(vma->vm_mm); |
| if (unlikely(!pgtable)) { |
| ret = VM_FAULT_OOM; |
| goto release; |
| } |
| |
| clear_huge_page(page, vmf->address, HPAGE_PMD_NR); |
| /* |
| * The memory barrier inside __SetPageUptodate makes sure that |
| * clear_huge_page writes become visible before the set_pmd_at() |
| * write. |
| */ |
| __SetPageUptodate(page); |
| |
| vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
| if (unlikely(!pmd_none(*vmf->pmd))) { |
| goto unlock_release; |
| } else { |
| pmd_t entry; |
| |
| 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); |
| put_page(page); |
| pte_free(vma->vm_mm, pgtable); |
| ret = handle_userfault(vmf, VM_UFFD_MISSING); |
| VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
| return ret; |
| } |
| |
| entry = mk_huge_pmd(page, vma->vm_page_prot); |
| entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| page_add_new_anon_rmap(page, vma, haddr, true); |
| lru_cache_add_inactive_or_unevictable(page, vma); |
| pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); |
| set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); |
| update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); |
| add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
| mm_inc_nr_ptes(vma->vm_mm); |
| spin_unlock(vmf->ptl); |
| count_vm_event(THP_FAULT_ALLOC); |
| count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); |
| } |
| |
| return 0; |
| unlock_release: |
| spin_unlock(vmf->ptl); |
| release: |
| if (pgtable) |
| pte_free(vma->vm_mm, pgtable); |
| put_page(page); |
| 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_page(pgtable_t pgtable, struct mm_struct *mm, |
| struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
| struct page *zero_page) |
| { |
| pmd_t entry; |
| if (!pmd_none(*pmd)) |
| return; |
| entry = mk_pmd(zero_page, vma->vm_page_prot); |
| entry = pmd_mkhuge(entry); |
| if (pgtable) |
| 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; |
| gfp_t gfp; |
| struct page *page; |
| unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
| |
| if (!transhuge_vma_suitable(vma, haddr)) |
| return VM_FAULT_FALLBACK; |
| if (unlikely(anon_vma_prepare(vma))) |
| return VM_FAULT_OOM; |
| if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
| return VM_FAULT_OOM; |
| if (!(vmf->flags & FAULT_FLAG_WRITE) && |
| !mm_forbids_zeropage(vma->vm_mm) && |
| transparent_hugepage_use_zero_page()) { |
| pgtable_t pgtable; |
| struct page *zero_page; |
| vm_fault_t ret; |
| pgtable = pte_alloc_one(vma->vm_mm); |
| if (unlikely(!pgtable)) |
| return VM_FAULT_OOM; |
| zero_page = mm_get_huge_zero_page(vma->vm_mm); |
| if (unlikely(!zero_page)) { |
| 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_page(pgtable, vma->vm_mm, vma, |
| haddr, vmf->pmd, zero_page); |
| 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; |
| } |
| gfp = vma_thp_gfp_mask(vma); |
| page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
| if (unlikely(!page)) { |
| count_vm_event(THP_FAULT_FALLBACK); |
| return VM_FAULT_FALLBACK; |
| } |
| prep_transhuge_page(page); |
| return __do_huge_pmd_anonymous_page(vmf, page, gfp); |
| } |
| |
| static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
| pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, |
| pgtable_t pgtable) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pmd_t entry; |
| spinlock_t *ptl; |
| |
| ptl = pmd_lock(mm, pmd); |
| if (!pmd_none(*pmd)) { |
| if (write) { |
| if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { |
| WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); |
| goto out_unlock; |
| } |
| entry = pmd_mkyoung(*pmd); |
| entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) |
| update_mmu_cache_pmd(vma, addr, pmd); |
| } |
| |
| goto out_unlock; |
| } |
| |
| entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
| if (pfn_t_devmap(pfn)) |
| entry = pmd_mkdevmap(entry); |
| if (write) { |
| entry = pmd_mkyoung(pmd_mkdirty(entry)); |
| entry = maybe_pmd_mkwrite(entry, vma); |
| } |
| |
| if (pgtable) { |
| pgtable_trans_huge_deposit(mm, pmd, pgtable); |
| mm_inc_nr_ptes(mm); |
| pgtable = NULL; |
| } |
| |
| set_pmd_at(mm, addr, pmd, entry); |
| update_mmu_cache_pmd(vma, addr, pmd); |
| |
| out_unlock: |
| spin_unlock(ptl); |
| if (pgtable) |
| pte_free(mm, pgtable); |
| } |
| |
| /** |
| * vmf_insert_pfn_pmd_prot - insert a pmd size pfn |
| * @vmf: Structure describing the fault |
| * @pfn: pfn to insert |
| * @pgprot: page protection to use |
| * @write: whether it's a write fault |
| * |
| * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and |
| * also consult the vmf_insert_mixed_prot() documentation when |
| * @pgprot != @vmf->vma->vm_page_prot. |
| * |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, |
| pgprot_t pgprot, bool write) |
| { |
| unsigned long addr = vmf->address & PMD_MASK; |
| struct vm_area_struct *vma = vmf->vma; |
| pgtable_t pgtable = NULL; |
| |
| /* |
| * 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)) && |
| !pfn_t_devmap(pfn)); |
| 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; |
| } |
| |
| track_pfn_insert(vma, &pgprot, pfn); |
| |
| insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); |
| return VM_FAULT_NOPAGE; |
| } |
| EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); |
| |
| #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_pfn_pud(struct vm_area_struct *vma, unsigned long addr, |
| pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pud_t entry; |
| spinlock_t *ptl; |
| |
| ptl = pud_lock(mm, pud); |
| if (!pud_none(*pud)) { |
| if (write) { |
| if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { |
| WARN_ON_ONCE(!is_huge_zero_pud(*pud)); |
| goto out_unlock; |
| } |
| entry = pud_mkyoung(*pud); |
| entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); |
| if (pudp_set_access_flags(vma, addr, pud, entry, 1)) |
| update_mmu_cache_pud(vma, addr, pud); |
| } |
| goto out_unlock; |
| } |
| |
| entry = pud_mkhuge(pfn_t_pud(pfn, prot)); |
| if (pfn_t_devmap(pfn)) |
| entry = pud_mkdevmap(entry); |
| if (write) { |
| entry = pud_mkyoung(pud_mkdirty(entry)); |
| entry = maybe_pud_mkwrite(entry, vma); |
| } |
| set_pud_at(mm, addr, pud, entry); |
| update_mmu_cache_pud(vma, addr, pud); |
| |
| out_unlock: |
| spin_unlock(ptl); |
| } |
| |
| /** |
| * vmf_insert_pfn_pud_prot - insert a pud size pfn |
| * @vmf: Structure describing the fault |
| * @pfn: pfn to insert |
| * @pgprot: page protection to use |
| * @write: whether it's a write fault |
| * |
| * Insert a pud size pfn. See vmf_insert_pfn() for additional info and |
| * also consult the vmf_insert_mixed_prot() documentation when |
| * @pgprot != @vmf->vma->vm_page_prot. |
| * |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, |
| pgprot_t pgprot, bool write) |
| { |
| unsigned long addr = vmf->address & PUD_MASK; |
| struct vm_area_struct *vma = vmf->vma; |
| |
| /* |
| * 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)) && |
| !pfn_t_devmap(pfn)); |
| 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; |
| |
| track_pfn_insert(vma, &pgprot, pfn); |
| |
| insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); |
| return VM_FAULT_NOPAGE; |
| } |
| EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); |
| #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
| |
| static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
| pmd_t *pmd, int flags) |
| { |
| pmd_t _pmd; |
| |
| _pmd = pmd_mkyoung(*pmd); |
| if (flags & FOLL_WRITE) |
| _pmd = pmd_mkdirty(_pmd); |
| if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, |
| pmd, _pmd, flags & FOLL_WRITE)) |
| update_mmu_cache_pmd(vma, addr, pmd); |
| } |
| |
| struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, |
| pmd_t *pmd, int flags, struct dev_pagemap **pgmap) |
| { |
| unsigned long pfn = pmd_pfn(*pmd); |
| struct mm_struct *mm = vma->vm_mm; |
| struct page *page; |
| |
| assert_spin_locked(pmd_lockptr(mm, pmd)); |
| |
| /* |
| * When we COW a devmap PMD entry, we split it into PTEs, so we should |
| * not be in this function with `flags & FOLL_COW` set. |
| */ |
| WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); |
| |
| /* FOLL_GET and FOLL_PIN are mutually exclusive. */ |
| if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == |
| (FOLL_PIN | FOLL_GET))) |
| return NULL; |
| |
| if (flags & FOLL_WRITE && !pmd_write(*pmd)) |
| return NULL; |
| |
| if (pmd_present(*pmd) && pmd_devmap(*pmd)) |
| /* pass */; |
| else |
| return NULL; |
| |
| if (flags & FOLL_TOUCH) |
| touch_pmd(vma, addr, pmd, flags); |
| |
| /* |
| * device mapped pages can only be returned if the |
| * caller will manage the page reference count. |
| */ |
| if (!(flags & (FOLL_GET | FOLL_PIN))) |
| return ERR_PTR(-EEXIST); |
| |
| pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; |
| *pgmap = get_dev_pagemap(pfn, *pgmap); |
| if (!*pgmap) |
| return ERR_PTR(-EFAULT); |
| page = pfn_to_page(pfn); |
| if (!try_grab_page(page, flags)) |
| page = ERR_PTR(-ENOMEM); |
| |
| return page; |
| } |
| |
| 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; |
| pmd_t pmd; |
| pgtable_t pgtable = NULL; |
| int ret = -ENOMEM; |
| |
| /* 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_writable_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)) { |
| /* |
| * get_huge_zero_page() will never allocate a new page here, |
| * since we already have a zero page to copy. It just takes a |
| * reference. |
| */ |
| mm_get_huge_zero_page(dst_mm); |
| goto out_zero_page; |
| } |
| |
| src_page = pmd_page(pmd); |
| VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |
| |
| /* |
| * If this page is a potentially pinned page, split and retry the fault |
| * with smaller page size. Normally this should not happen because the |
| * userspace should use MADV_DONTFORK upon pinned regions. This is a |
| * best effort that the pinned pages won't be replaced by another |
| * random page during the coming copy-on-write. |
| */ |
| if (unlikely(page_needs_cow_for_dma(src_vma, src_page))) { |
| pte_free(dst_mm, pgtable); |
| spin_unlock(src_ptl); |
| spin_unlock(dst_ptl); |
| __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); |
| return -EAGAIN; |
| } |
| |
| get_page(src_page); |
| page_dup_rmap(src_page, true); |
| 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_mkold(pmd_wrprotect(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 |
| static void touch_pud(struct vm_area_struct *vma, unsigned long addr, |
| pud_t *pud, int flags) |
| { |
| pud_t _pud; |
| |
| _pud = pud_mkyoung(*pud); |
| if (flags & FOLL_WRITE) |
| _pud = pud_mkdirty(_pud); |
| if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, |
| pud, _pud, flags & FOLL_WRITE)) |
| update_mmu_cache_pud(vma, addr, pud); |
| } |
| |
| struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, |
| pud_t *pud, int flags, struct dev_pagemap **pgmap) |
| { |
| unsigned long pfn = pud_pfn(*pud); |
| struct mm_struct *mm = vma->vm_mm; |
| struct page *page; |
| |
| assert_spin_locked(pud_lockptr(mm, pud)); |
| |
| if (flags & FOLL_WRITE && !pud_write(*pud)) |
| return NULL; |
| |
| /* FOLL_GET and FOLL_PIN are mutually exclusive. */ |
| if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == |
| (FOLL_PIN | FOLL_GET))) |
| return NULL; |
| |
| if (pud_present(*pud) && pud_devmap(*pud)) |
| /* pass */; |
| else |
| return NULL; |
| |
| if (flags & FOLL_TOUCH) |
| touch_pud(vma, addr, pud, flags); |
| |
| /* |
| * device mapped pages can only be returned if the |
| * caller will manage the page reference count. |
| * |
| * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: |
| */ |
| if (!(flags & (FOLL_GET | FOLL_PIN))) |
| return ERR_PTR(-EEXIST); |
| |
| pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; |
| *pgmap = get_dev_pagemap(pfn, *pgmap); |
| if (!*pgmap) |
| return ERR_PTR(-EFAULT); |
| page = pfn_to_page(pfn); |
| if (!try_grab_page(page, flags)) |
| page = ERR_PTR(-ENOMEM); |
| |
| return page; |
| } |
| |
| 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) && !pud_devmap(pud))) |
| goto out_unlock; |
| |
| /* |
| * When page table lock is held, the huge zero pud should not be |
| * under splitting since we don't split the page itself, only pud to |
| * a page table. |
| */ |
| if (is_huge_zero_pud(pud)) { |
| /* No huge zero pud yet */ |
| } |
| |
| /* Please refer to comments in copy_huge_pmd() */ |
| if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) { |
| spin_unlock(src_ptl); |
| spin_unlock(dst_ptl); |
| __split_huge_pud(vma, src_pud, addr); |
| return -EAGAIN; |
| } |
| |
| pudp_set_wrprotect(src_mm, addr, src_pud); |
| pud = pud_mkold(pud_wrprotect(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) |
| { |
| pud_t entry; |
| unsigned long haddr; |
| 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; |
| |
| entry = pud_mkyoung(orig_pud); |
| if (write) |
| entry = pud_mkdirty(entry); |
| haddr = vmf->address & HPAGE_PUD_MASK; |
| if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) |
| update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); |
| |
| unlock: |
| spin_unlock(vmf->ptl); |
| } |
| #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ |
| |
| void huge_pmd_set_accessed(struct vm_fault *vmf) |
| { |
| pmd_t entry; |
| unsigned long haddr; |
| bool write = vmf->flags & FAULT_FLAG_WRITE; |
| pmd_t orig_pmd = vmf->orig_pmd; |
| |
| vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); |
| if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) |
| goto unlock; |
| |
| entry = pmd_mkyoung(orig_pmd); |
| if (write) |
| entry = pmd_mkdirty(entry); |
| haddr = vmf->address & HPAGE_PMD_MASK; |
| if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) |
| update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); |
| |
| unlock: |
| spin_unlock(vmf->ptl); |
| } |
| |
| vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| 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)) |
| 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); |
| VM_BUG_ON_PAGE(!PageHead(page), page); |
| |
| /* Lock page for reuse_swap_page() */ |
| if (!trylock_page(page)) { |
| get_page(page); |
| spin_unlock(vmf->ptl); |
| lock_page(page); |
| spin_lock(vmf->ptl); |
| if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { |
| spin_unlock(vmf->ptl); |
| unlock_page(page); |
| put_page(page); |
| return 0; |
| } |
| put_page(page); |
| } |
| |
| /* |
| * We can only reuse the page if nobody else maps the huge page or it's |
| * part. |
| */ |
| if (reuse_swap_page(page, NULL)) { |
| pmd_t entry; |
| 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); |
| unlock_page(page); |
| spin_unlock(vmf->ptl); |
| return VM_FAULT_WRITE; |
| } |
| |
| unlock_page(page); |
| spin_unlock(vmf->ptl); |
| fallback: |
| __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); |
| return VM_FAULT_FALLBACK; |
| } |
| |
| /* |
| * FOLL_FORCE can write to even unwritable pmd's, but only |
| * after we've gone through a COW cycle and they are dirty. |
| */ |
| static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) |
| { |
| return pmd_write(pmd) || |
| ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); |
| } |
| |
| struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
| unsigned long addr, |
| pmd_t *pmd, |
| unsigned int flags) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct page *page = NULL; |
| |
| assert_spin_locked(pmd_lockptr(mm, pmd)); |
| |
| if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) |
| goto out; |
| |
| /* Avoid dumping huge zero page */ |
| if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) |
| return ERR_PTR(-EFAULT); |
| |
| /* Full NUMA hinting faults to serialise migration in fault paths */ |
| if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
| goto out; |
| |
| page = pmd_page(*pmd); |
| VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); |
| |
| if (!try_grab_page(page, flags)) |
| return ERR_PTR(-ENOMEM); |
| |
| if (flags & FOLL_TOUCH) |
| touch_pmd(vma, addr, pmd, flags); |
| |
| if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
| /* |
| * We don't mlock() pte-mapped THPs. This way we can avoid |
| * leaking mlocked pages into non-VM_LOCKED VMAs. |
| * |
| * For anon THP: |
| * |
| * In most cases the pmd is the only mapping of the page as we |
| * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for |
| * writable private mappings in populate_vma_page_range(). |
| * |
| * The only scenario when we have the page shared here is if we |
| * mlocking read-only mapping shared over fork(). We skip |
| * mlocking such pages. |
| * |
| * For file THP: |
| * |
| * We can expect PageDoubleMap() to be stable under page lock: |
| * for file pages we set it in page_add_file_rmap(), which |
| * requires page to be locked. |
| */ |
| |
| if (PageAnon(page) && compound_mapcount(page) != 1) |
| goto skip_mlock; |
| if (PageDoubleMap(page) || !page->mapping) |
| goto skip_mlock; |
| if (!trylock_page(page)) |
| goto skip_mlock; |
| if (page->mapping && !PageDoubleMap(page)) |
| mlock_vma_page(page); |
| unlock_page(page); |
| } |
| skip_mlock: |
| page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
| VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); |
| |
| out: |
| return page; |
| } |
| |
| /* 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; |
| pmd_t oldpmd = vmf->orig_pmd; |
| pmd_t pmd; |
| struct page *page; |
| unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
| int page_nid = NUMA_NO_NODE; |
| int target_nid, last_cpupid = -1; |
| bool migrated = false; |
| bool was_writable = pmd_savedwrite(oldpmd); |
| int flags = 0; |
| |
| vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
| if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { |
| spin_unlock(vmf->ptl); |
| goto out; |
| } |
| |
| /* |
| * Since we took the NUMA fault, we must have observed the !accessible |
| * bit. Make sure all other CPUs agree with that, to avoid them |
| * modifying the page we're about to migrate. |
| * |
| * Must be done under PTL such that we'll observe the relevant |
| * inc_tlb_flush_pending(). |
| * |
| * We are not sure a pending tlb flush here is for a huge page |
| * mapping or not. Hence use the tlb range variant |
| */ |
| if (mm_tlb_flush_pending(vma->vm_mm)) { |
| flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); |
| /* |
| * change_huge_pmd() released the pmd lock before |
| * invalidating the secondary MMUs sharing the primary |
| * MMU pagetables (with ->invalidate_range()). The |
| * mmu_notifier_invalidate_range_end() (which |
| * internally calls ->invalidate_range()) in |
| * change_pmd_range() will run after us, so we can't |
| * rely on it here and we need an explicit invalidate. |
| */ |
| mmu_notifier_invalidate_range(vma->vm_mm, haddr, |
| haddr + HPAGE_PMD_SIZE); |
| } |
| |
| pmd = pmd_modify(oldpmd, vma->vm_page_prot); |
| page = vm_normal_page_pmd(vma, haddr, pmd); |
| if (!page) |
| goto out_map; |
| |
| /* See similar comment in do_numa_page for explanation */ |
| if (!was_writable) |
| flags |= TNF_NO_GROUP; |
| |
| page_nid = page_to_nid(page); |
| last_cpupid = page_cpupid_last(page); |
| target_nid = numa_migrate_prep(page, vma, haddr, page_nid, |
| &flags); |
| |
| if (target_nid == NUMA_NO_NODE) { |
| put_page(page); |
| goto out_map; |
| } |
| |
| spin_unlock(vmf->ptl); |
| |
| migrated = migrate_misplaced_page(page, vma, target_nid); |
| if (migrated) { |
| flags |= TNF_MIGRATED; |
| page_nid = target_nid; |
| } else { |
| flags |= TNF_MIGRATE_FAIL; |
| vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
| if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { |
| spin_unlock(vmf->ptl); |
| goto out; |
| } |
| goto out_map; |
| } |
| |
| out: |
| if (page_nid != NUMA_NO_NODE) |
| task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, |
| flags); |
| |
| return 0; |
| |
| out_map: |
| /* Restore the PMD */ |
| pmd = pmd_modify(oldpmd, vma->vm_page_prot); |
| pmd = pmd_mkyoung(pmd); |
| if (was_writable) |
| pmd = pmd_mkwrite(pmd); |
| set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); |
| update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); |
| spin_unlock(vmf->ptl); |
| goto out; |
| } |
| |
| /* |
| * 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 page *page; |
| 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; |
| } |
| |
| page = pmd_page(orig_pmd); |
| /* |
| * If other processes are mapping this page, we couldn't discard |
| * the page unless they all do MADV_FREE so let's skip the page. |
| */ |
| if (total_mapcount(page) != 1) |
| goto out; |
| |
| if (!trylock_page(page)) |
| 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) { |
| get_page(page); |
| spin_unlock(ptl); |
| split_huge_page(page); |
| unlock_page(page); |
| put_page(page); |
| goto out_unlocked; |
| } |
| |
| if (PageDirty(page)) |
| ClearPageDirty(page); |
| unlock_page(page); |
| |
| 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); |
| } |
| |
| mark_page_lazyfree(page); |
| 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); |
| tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
| if (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)) { |
| zap_deposited_table(tlb->mm, pmd); |
| spin_unlock(ptl); |
| } else { |
| struct page *page = NULL; |
| int flush_needed = 1; |
| |
| if (pmd_present(orig_pmd)) { |
| page = pmd_page(orig_pmd); |
| page_remove_rmap(page, true); |
| VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
| 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); |
| page = pfn_swap_entry_to_page(entry); |
| flush_needed = 0; |
| } else |
| WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); |
| |
| if (PageAnon(page)) { |
| 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(page), -HPAGE_PMD_NR); |
| } |
| |
| spin_unlock(ptl); |
| if (flush_needed) |
| tlb_remove_page_size(tlb, 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; |
| } |
| |
| 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 release it. |
| */ |
| if (WARN_ON(!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); |
| set_pmd_at(mm, new_addr, new_pmd, pmd); |
| if (force_flush) |
| flush_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 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 entry; |
| bool preserve_write; |
| int ret; |
| 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; |
| |
| if (prot_numa && !thp_migration_supported()) |
| return 1; |
| |
| ptl = __pmd_trans_huge_lock(pmd, vma); |
| if (!ptl) |
| return 0; |
| |
| preserve_write = prot_numa && pmd_write(*pmd); |
| ret = 1; |
| |
| #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
| if (is_swap_pmd(*pmd)) { |
| swp_entry_t entry = pmd_to_swp_entry(*pmd); |
| |
| VM_BUG_ON(!is_pmd_migration_entry(*pmd)); |
| if (is_writable_migration_entry(entry)) { |
| pmd_t newpmd; |
| /* |
| * A protection check is difficult so |
| * just be safe and disable write |
| */ |
| 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); |
| if (pmd_swp_uffd_wp(*pmd)) |
| newpmd = pmd_swp_mkuffd_wp(newpmd); |
| set_pmd_at(mm, addr, pmd, newpmd); |
| } |
| goto unlock; |
| } |
| #endif |
| |
| /* |
| * 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 (prot_numa && is_huge_zero_pmd(*pmd)) |
| goto unlock; |
| |
| if (prot_numa && pmd_protnone(*pmd)) |
| goto unlock; |
| |
| /* |
| * In case prot_numa, we are under mmap_read_lock(mm). It's critical |
| * to not clear pmd intermittently to avoid race with MADV_DONTNEED |
| * which is also under mmap_read_lock(mm): |
| * |
| * CPU0: CPU1: |
| * change_huge_pmd(prot_numa=1) |
| * pmdp_huge_get_and_clear_notify() |
| * madvise_dontneed() |
| * zap_pmd_range() |
| * pmd_trans_huge(*pmd) == 0 (without ptl) |
| * // skip the pmd |
| * set_pmd_at(); |
| * // pmd is re-established |
| * |
| * The race makes MADV_DONTNEED miss the huge pmd and don't clear it |
| * which may break userspace. |
| * |
| * pmdp_invalidate() is required to make sure we don't miss |
| * dirty/young flags set by hardware. |
| */ |
| entry = pmdp_invalidate(vma, addr, pmd); |
| |
| entry = pmd_modify(entry, newprot); |
| if (preserve_write) |
| entry = pmd_mk_savedwrite(entry); |
| if (uffd_wp) { |
| entry = pmd_wrprotect(entry); |
| 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); |
| } |
| ret = HPAGE_PMD_NR; |
| set_pmd_at(mm, addr, pmd, entry); |
| BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); |
| unlock: |
| spin_unlock(ptl); |
| return ret; |
| } |
| |
| /* |
| * 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) || |
| pmd_devmap(*pmd))) |
| return ptl; |
| spin_unlock(ptl); |
| return NULL; |
| } |
| |
| /* |
| * Returns true if a given pud maps a thp, false otherwise. |
| * |
| * Note that if it returns true, 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) || pud_devmap(*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; |
| |
| ptl = __pud_trans_huge_lock(pud, vma); |
| if (!ptl) |
| return 0; |
| /* |
| * For architectures like ppc64 we look at deposited pgtable |
| * when calling pudp_huge_get_and_clear. So do the |
| * pgtable_trans_huge_withdraw after finishing pudp related |
| * operations. |
| */ |
| pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); |
| tlb_remove_pud_tlb_entry(tlb, pud, addr); |
| if (vma_is_special_huge(vma)) { |
| spin_unlock(ptl); |
| /* No zero page support yet */ |
| } else { |
| /* No support for anonymous PUD pages yet */ |
| BUG(); |
| } |
| return 1; |
| } |
| |
| static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, |
| unsigned long haddr) |
| { |
| 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) && !pud_devmap(*pud)); |
| |
| count_vm_event(THP_SPLIT_PUD); |
| |
| pudp_huge_clear_flush_notify(vma, haddr, pud); |
| } |
| |
| 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, 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) && !pud_devmap(*pud))) |
| goto out; |
| __split_huge_pud_locked(vma, pud, range.start); |
| |
| out: |
| spin_unlock(ptl); |
| /* |
| * No need to double call mmu_notifier->invalidate_range() callback as |
| * the above pudp_huge_clear_flush_notify() did already call it. |
| */ |
| mmu_notifier_invalidate_range_only_end(&range); |
| } |
| #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; |
| 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/vm/mmu_notifier.rst |
| */ |
| pmdp_huge_clear_flush(vma, haddr, pmd); |
| |
| pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
| pmd_populate(mm, &_pmd, pgtable); |
| |
| for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { |
| pte_t *pte, entry; |
| entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); |
| entry = pte_mkspecial(entry); |
| pte = pte_offset_map(&_pmd, haddr); |
| VM_BUG_ON(!pte_none(*pte)); |
| set_pte_at(mm, haddr, pte, entry); |
| pte_unmap(pte); |
| } |
| 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 page *page; |
| pgtable_t pgtable; |
| pmd_t old_pmd, _pmd; |
| bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; |
| unsigned long addr; |
| 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) |
| && !pmd_devmap(*pmd)); |
| |
| count_vm_event(THP_SPLIT_PMD); |
| |
| if (!vma_is_anonymous(vma)) { |
| old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); |
| /* |
| * We are going to unmap this huge page. So |
| * just go ahead and zap it |
| */ |
| if (arch_needs_pgtable_deposit()) |
| zap_deposited_table(mm, pmd); |
| if (vma_is_special_huge(vma)) |
| return; |
| if (unlikely(is_pmd_migration_entry(old_pmd))) { |
| swp_entry_t entry; |
| |
| entry = pmd_to_swp_entry(old_pmd); |
| page = pfn_swap_entry_to_page(entry); |
| } else { |
| page = pmd_page(old_pmd); |
| if (!PageDirty(page) && pmd_dirty(old_pmd)) |
| set_page_dirty(page); |
| if (!PageReferenced(page) && pmd_young(old_pmd)) |
| SetPageReferenced(page); |
| page_remove_rmap(page, true); |
| put_page(page); |
| } |
| add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); |
| return; |
| } |
| |
| if (is_huge_zero_pmd(*pmd)) { |
| /* |
| * FIXME: Do we want to invalidate secondary mmu by calling |
| * mmu_notifier_invalidate_range() 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); |
| } |
| |
| /* |
| * 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); |
| |
| pmd_migration = is_pmd_migration_entry(old_pmd); |
| if (unlikely(pmd_migration)) { |
| swp_entry_t entry; |
| |
| entry = pmd_to_swp_entry(old_pmd); |
| page = pfn_swap_entry_to_page(entry); |
| write = is_writable_migration_entry(entry); |
| young = false; |
| soft_dirty = pmd_swp_soft_dirty(old_pmd); |
| uffd_wp = pmd_swp_uffd_wp(old_pmd); |
| } else { |
| page = pmd_page(old_pmd); |
| if (pmd_dirty(old_pmd)) |
| SetPageDirty(page); |
| 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_BUG_ON_PAGE(!page_count(page), page); |
| page_ref_add(page, HPAGE_PMD_NR - 1); |
| |
| /* |
| * 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); |
| |
| for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
| pte_t entry, *pte; |
| /* |
| * Note that NUMA hinting access restrictions are not |
| * transferred to avoid any possibility of altering |
| * permissions across VMAs. |
| */ |
| if (freeze || pmd_migration) { |
| swp_entry_t swp_entry; |
| if (write) |
| swp_entry = make_writable_migration_entry( |
| page_to_pfn(page + i)); |
| else |
| swp_entry = make_readable_migration_entry( |
| page_to_pfn(page + i)); |
| 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); |
| } else { |
| entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); |
| entry = maybe_mkwrite(entry, vma); |
| if (!write) |
| entry = pte_wrprotect(entry); |
| if (!young) |
| entry = pte_mkold(entry); |
| if (soft_dirty) |
| entry = pte_mksoft_dirty(entry); |
| if (uffd_wp) |
| entry = pte_mkuffd_wp(entry); |
| } |
| pte = pte_offset_map(&_pmd, addr); |
| BUG_ON(!pte_none(*pte)); |
| set_pte_at(mm, addr, pte, entry); |
| if (!pmd_migration) |
| atomic_inc(&page[i]._mapcount); |
| pte_unmap(pte); |
| } |
| |
| if (!pmd_migration) { |
| /* |
| * Set PG_double_map before dropping compound_mapcount to avoid |
| * false-negative page_mapped(). |
| */ |
| if (compound_mapcount(page) > 1 && |
| !TestSetPageDoubleMap(page)) { |
| for (i = 0; i < HPAGE_PMD_NR; i++) |
| atomic_inc(&page[i]._mapcount); |
| } |
| |
| lock_page_memcg(page); |
| if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { |
| /* Last compound_mapcount is gone. */ |
| __mod_lruvec_page_state(page, NR_ANON_THPS, |
| -HPAGE_PMD_NR); |
| if (TestClearPageDoubleMap(page)) { |
| /* No need in mapcount reference anymore */ |
| for (i = 0; i < HPAGE_PMD_NR; i++) |
| atomic_dec(&page[i]._mapcount); |
| } |
| } |
| unlock_page_memcg(page); |
| } |
| |
| smp_wmb(); /* make pte visible before pmd */ |
| pmd_populate(mm, pmd, pgtable); |
| |
| if (freeze) { |
| for (i = 0; i < HPAGE_PMD_NR; i++) { |
| page_remove_rmap(page + i, false); |
| put_page(page + i); |
| } |
| } |
| } |
| |
| void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long address, bool freeze, struct page *page) |
| { |
| spinlock_t *ptl; |
| struct mmu_notifier_range range; |
| bool do_unlock_page = false; |
| pmd_t _pmd; |
| |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, 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); |
| |
| /* |
| * If caller asks to setup a migration entries, we need a page to check |
| * pmd against. Otherwise we can end up replacing wrong page. |
| */ |
| VM_BUG_ON(freeze && !page); |
| if (page) { |
| VM_WARN_ON_ONCE(!PageLocked(page)); |
| if (page != pmd_page(*pmd)) |
| goto out; |
| } |
| |
| repeat: |
| if (pmd_trans_huge(*pmd)) { |
| if (!page) { |
| page = pmd_page(*pmd); |
| /* |
| * An anonymous page must be locked, to ensure that a |
| * concurrent reuse_swap_page() sees stable mapcount; |
| * but reuse_swap_page() is not used on shmem or file, |
| * and page lock must not be taken when zap_pmd_range() |
| * calls __split_huge_pmd() while i_mmap_lock is held. |
| */ |
| if (PageAnon(page)) { |
| if (unlikely(!trylock_page(page))) { |
| get_page(page); |
| _pmd = *pmd; |
| spin_unlock(ptl); |
| lock_page(page); |
| spin_lock(ptl); |
| if (unlikely(!pmd_same(*pmd, _pmd))) { |
| unlock_page(page); |
| put_page(page); |
| page = NULL; |
| goto repeat; |
| } |
| put_page(page); |
| } |
| do_unlock_page = true; |
| } |
| } |
| if (PageMlocked(page)) |
| clear_page_mlock(page); |
| } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) |
| goto out; |
| __split_huge_pmd_locked(vma, pmd, range.start, freeze); |
| out: |
| spin_unlock(ptl); |
| if (do_unlock_page) |
| unlock_page(page); |
| /* |
| * No need to double call mmu_notifier->invalidate_range() callback. |
| * They are 3 cases to consider inside __split_huge_pmd_locked(): |
| * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious |
| * 2) __split_huge_zero_page_pmd() read only zero page and any write |
| * fault will trigger a flush_notify before pointing to a new page |
| * (it is fine if the secondary mmu keeps pointing to the old zero |
| * page in the meantime) |
| * 3) Split a huge pmd into pte pointing to the same page. No need |
| * to invalidate secondary tlb entry they are all still valid. |
| * any further changes to individual pte will notify. So no need |
| * to call mmu_notifier->invalidate_range() |
| */ |
| mmu_notifier_invalidate_range_only_end(&range); |
| } |
| |
| void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
| bool freeze, struct page *page) |
| { |
| pgd_t *pgd; |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| pgd = pgd_offset(vma->vm_mm, address); |
| if (!pgd_present(*pgd)) |
| return; |
| |
| p4d = p4d_offset(pgd, address); |
| if (!p4d_present(*p4d)) |
| return; |
| |
| pud = pud_offset(p4d, address); |
| if (!pud_present(*pud)) |
| return; |
| |
| pmd = pmd_offset(pud, address); |
| |
| __split_huge_pmd(vma, pmd, address, freeze, page); |
| } |
| |
| static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) |
| { |
| /* |
| * If the new address isn't hpage aligned and it could previously |
| * contain an hugepage: check if we need to split an huge pmd. |
| */ |
| if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && |
| range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), |
| ALIGN(address, HPAGE_PMD_SIZE))) |
| split_huge_pmd_address(vma, address, false, NULL); |
| } |
| |
| void vma_adjust_trans_huge(struct vm_area_struct *vma, |
| unsigned long start, |
| unsigned long end, |
| long adjust_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 also updating the vma->vm_next->vm_start, |
| * check if we need to split it. |
| */ |
| if (adjust_next > 0) { |
| struct vm_area_struct *next = vma->vm_next; |
| unsigned long nstart = next->vm_start; |
| nstart += adjust_next; |
| split_huge_pmd_if_needed(next, nstart); |
| } |
| } |
| |
| static void unmap_page(struct page *page) |
| { |
| enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | |
| TTU_SYNC; |
| |
| VM_BUG_ON_PAGE(!PageHead(page), page); |
| |
| /* |
| * 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 (PageAnon(page)) |
| try_to_migrate(page, ttu_flags); |
| else |
| try_to_unmap(page, ttu_flags | TTU_IGNORE_MLOCK); |
| |
| VM_WARN_ON_ONCE_PAGE(page_mapped(page), page); |
| } |
| |
| static void remap_page(struct page *page, unsigned int nr) |
| { |
| int i; |
| |
| /* If unmap_page() uses try_to_migrate() on file, remove this check */ |
| if (!PageAnon(page)) |
| return; |
| if (PageTransHuge(page)) { |
| remove_migration_ptes(page, page, true); |
| } else { |
| for (i = 0; i < nr; i++) |
| remove_migration_ptes(page + i, page + i, true); |
| } |
| } |
| |
| static void lru_add_page_tail(struct page *head, struct page *tail, |
| struct lruvec *lruvec, struct list_head *list) |
| { |
| VM_BUG_ON_PAGE(!PageHead(head), head); |
| VM_BUG_ON_PAGE(PageCompound(tail), head); |
| VM_BUG_ON_PAGE(PageLRU(tail), head); |
| lockdep_assert_held(&lruvec->lru_lock); |
| |
| if (list) { |
| /* page reclaim is reclaiming a huge page */ |
| VM_WARN_ON(PageLRU(head)); |
| get_page(tail); |
| list_add_tail(&tail->lru, list); |
| } else { |
| /* head is still on lru (and we have it frozen) */ |
| VM_WARN_ON(!PageLRU(head)); |
| SetPageLRU(tail); |
| list_add_tail(&tail->lru, &head->lru); |
| } |
| } |
| |
| static void __split_huge_page_tail(struct page *head, int tail, |
| struct lruvec *lruvec, struct list_head *list) |
| { |
| struct page *page_tail = head + tail; |
| |
| VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
| |
| /* |
| * Clone page flags before unfreezing refcount. |
| * |
| * After successful get_page_unless_zero() might follow flags change, |
| * for example lock_page() which set PG_waiters. |
| */ |
| page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; |
| page_tail->flags |= (head->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_64BIT |
| (1L << PG_arch_2) | |
| #endif |
| (1L << PG_dirty))); |
| |
| /* ->mapping in first tail page is compound_mapcount */ |
| VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
| page_tail); |
| page_tail->mapping = head->mapping; |
| page_tail->index = head->index + tail; |
| |
| /* 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(page_tail); |
| |
| /* Finally unfreeze refcount. Additional reference from page cache. */ |
| page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || |
| PageSwapCache(head))); |
| |
| if (page_is_young(head)) |
| set_page_young(page_tail); |
| if (page_is_idle(head)) |
| set_page_idle(page_tail); |
| |
| page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); |
| |
| /* |
| * always add to the tail because some iterators expect new |
| * pages to show after the currently processed elements - e.g. |
| * migrate_pages |
| */ |
| lru_add_page_tail(head, page_tail, lruvec, list); |
| } |
| |
| static void __split_huge_page(struct page *page, struct list_head *list, |
| pgoff_t end) |
| { |
| struct page *head = compound_head(page); |
| struct lruvec *lruvec; |
| struct address_space *swap_cache = NULL; |
| unsigned long offset = 0; |
| unsigned int nr = thp_nr_pages(head); |
| int i; |
| |
| /* complete memcg works before add pages to LRU */ |
| split_page_memcg(head, nr); |
| |
| if (PageAnon(head) && PageSwapCache(head)) { |
| swp_entry_t entry = { .val = page_private(head) }; |
| |
| offset = swp_offset(entry); |
| swap_cache = swap_address_space(entry); |
| xa_lock(&swap_cache->i_pages); |
| } |
| |
| /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ |
| lruvec = lock_page_lruvec(head); |
| |
| for (i = nr - 1; i >= 1; i--) { |
| __split_huge_page_tail(head, i, lruvec, list); |
| /* Some pages can be beyond i_size: drop them from page cache */ |
| if (head[i].index >= end) { |
| ClearPageDirty(head + i); |
| __delete_from_page_cache(head + i, NULL); |
| if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) |
| shmem_uncharge(head->mapping->host, 1); |
| put_page(head + i); |
| } else if (!PageAnon(page)) { |
| __xa_store(&head->mapping->i_pages, head[i].index, |
| head + i, 0); |
| } else if (swap_cache) { |
| __xa_store(&swap_cache->i_pages, offset + i, |
| head + i, 0); |
| } |
| } |
| |
| ClearPageCompound(head); |
| unlock_page_lruvec(lruvec); |
| /* Caller disabled irqs, so they are still disabled here */ |
| |
| split_page_owner(head, nr); |
| |
| /* See comment in __split_huge_page_tail() */ |
| if (PageAnon(head)) { |
| /* Additional pin to swap cache */ |
| if (PageSwapCache(head)) { |
| page_ref_add(head, 2); |
| xa_unlock(&swap_cache->i_pages); |
| } else { |
| page_ref_inc(head); |
| } |
| } else { |
| /* Additional pin to page cache */ |
| page_ref_add(head, 2); |
| xa_unlock(&head->mapping->i_pages); |
| } |
| local_irq_enable(); |
| |
| remap_page(head, nr); |
| |
| if (PageSwapCache(head)) { |
| swp_entry_t entry = { .val = page_private(head) }; |
| |
| split_swap_cluster(entry); |
| } |
| |
| for (i = 0; i < nr; i++) { |
| struct page *subpage = head + i; |
| if (subpage == page) |
| continue; |
| unlock_page(subpage); |
| |
| /* |
| * 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. |
| */ |
| put_page(subpage); |
| } |
| } |
| |
| int total_mapcount(struct page *page) |
| { |
| int i, compound, nr, ret; |
| |
| VM_BUG_ON_PAGE(PageTail(page), page); |
| |
| if (likely(!PageCompound(page))) |
| return atomic_read(&page->_mapcount) + 1; |
| |
| compound = compound_mapcount(page); |
| nr = compound_nr(page); |
| if (PageHuge(page)) |
| return compound; |
| ret = compound; |
| for (i = 0; i < nr; i++) |
| ret += atomic_read(&page[i]._mapcount) + 1; |
| /* File pages has compound_mapcount included in _mapcount */ |
| if (!PageAnon(page)) |
| return ret - compound * nr; |
| if (PageDoubleMap(page)) |
| ret -= nr; |
| return ret; |
| } |
| |
| /* |
| * This calculates accurately how many mappings a transparent hugepage |
| * has (unlike page_mapcount() which isn't fully accurate). This full |
| * accuracy is primarily needed to know if copy-on-write faults can |
| * reuse the page and change the mapping to read-write instead of |
| * copying them. At the same time this returns the total_mapcount too. |
| * |
| * The function returns the highest mapcount any one of the subpages |
| * has. If the return value is one, even if different processes are |
| * mapping different subpages of the transparent hugepage, they can |
| * all reuse it, because each process is reusing a different subpage. |
| * |
| * The total_mapcount is instead counting all virtual mappings of the |
| * subpages. If the total_mapcount is equal to "one", it tells the |
| * caller all mappings belong to the same "mm" and in turn the |
| * anon_vma of the transparent hugepage can become the vma->anon_vma |
| * local one as no other process may be mapping any of the subpages. |
| * |
| * It would be more accurate to replace page_mapcount() with |
| * page_trans_huge_mapcount(), however we only use |
| * page_trans_huge_mapcount() in the copy-on-write faults where we |
| * need full accuracy to avoid breaking page pinning, because |
| * page_trans_huge_mapcount() is slower than page_mapcount(). |
| */ |
| int page_trans_huge_mapcount(struct page *page, int *total_mapcount) |
| { |
| int i, ret, _total_mapcount, mapcount; |
| |
| /* hugetlbfs shouldn't call it */ |
| VM_BUG_ON_PAGE(PageHuge(page), page); |
| |
| if (likely(!PageTransCompound(page))) { |
| mapcount = atomic_read(&page->_mapcount) + 1; |
| if (total_mapcount) |
| *total_mapcount = mapcount; |
| return mapcount; |
| } |
| |
| page = compound_head(page); |
| |
| _total_mapcount = ret = 0; |
| for (i = 0; i < thp_nr_pages(page); i++) { |
| mapcount = atomic_read(&page[i]._mapcount) + 1; |
| ret = max(ret, mapcount); |
| _total_mapcount += mapcount; |
| } |
| if (PageDoubleMap(page)) { |
| ret -= 1; |
| _total_mapcount -= thp_nr_pages(page); |
| } |
| mapcount = compound_mapcount(page); |
| ret += mapcount; |
| _total_mapcount += mapcount; |
| if (total_mapcount) |
| *total_mapcount = _total_mapcount; |
| return ret; |
| } |
| |
| /* Racy check whether the huge page can be split */ |
| bool can_split_huge_page(struct page *page, int *pextra_pins) |
| { |
| int extra_pins; |
| |
| /* Additional pins from page cache */ |
| if (PageAnon(page)) |
| extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0; |
| else |
| extra_pins = thp_nr_pages(page); |
| if (pextra_pins) |
| *pextra_pins = extra_pins; |
| return total_mapcount(page) == page_count(page) - extra_pins - 1; |
| } |
| |
| /* |
| * This function splits huge page into normal pages. @page can point to any |
| * subpage of huge page to split. Split doesn't change the position of @page. |
| * |
| * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. |
| * The huge page must be locked. |
| * |
| * If @list is null, tail pages will be added to LRU list, otherwise, to @list. |
| * |
| * Both head page and tail pages will inherit mapping, flags, and so on from |
| * the hugepage. |
| * |
| * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if |
| * they are not mapped. |
| * |
| * Returns 0 if the hugepage is split successfully. |
| * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under |
| * us. |
| */ |
| int split_huge_page_to_list(struct page *page, struct list_head *list) |
| { |
| struct page *head = compound_head(page); |
| struct deferred_split *ds_queue = get_deferred_split_queue(head); |
| struct anon_vma *anon_vma = NULL; |
| struct address_space *mapping = NULL; |
| int extra_pins, ret; |
| pgoff_t end; |
| |
| VM_BUG_ON_PAGE(is_huge_zero_page(head), head); |
| VM_BUG_ON_PAGE(!PageLocked(head), head); |
| VM_BUG_ON_PAGE(!PageCompound(head), head); |
| |
| if (PageWriteback(head)) |
| return -EBUSY; |
| |
| if (PageAnon(head)) { |
| /* |
| * 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 page_lock_anon_vma_read except the write lock |
| * is taken to serialise against parallel split or collapse |
| * operations. |
| */ |
| anon_vma = page_get_anon_vma(head); |
| if (!anon_vma) { |
| ret = -EBUSY; |
| goto out; |
| } |
| end = -1; |
| mapping = NULL; |
| anon_vma_lock_write(anon_vma); |
| } else { |
| mapping = head->mapping; |
| |
| /* Truncated ? */ |
| if (!mapping) { |
| ret = -EBUSY; |
| goto out; |
| } |
| |
| anon_vma = NULL; |
| i_mmap_lock_read(mapping); |
| |
| /* |
| *__split_huge_page() 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 |
| * head page lock is good enough to serialize the trimming. |
| */ |
| end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); |
| } |
| |
| /* |
| * Racy check if we can split the page, before unmap_page() will |
| * split PMDs |
| */ |
| if (!can_split_huge_page(head, &extra_pins)) { |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
| |
| unmap_page(head); |
| |
| /* block interrupt reentry in xa_lock and spinlock */ |
| local_irq_disable(); |
| if (mapping) { |
| XA_STATE(xas, &mapping->i_pages, page_index(head)); |
| |
| /* |
| * Check if the head page is present in page cache. |
| * We assume all tail are present too, if head is there. |
| */ |
| xa_lock(&mapping->i_pages); |
| if (xas_load(&xas) != head) |
| goto fail; |
| } |
| |
| /* Prevent deferred_split_scan() touching ->_refcount */ |
| spin_lock(&ds_queue->split_queue_lock); |
| if (page_ref_freeze(head, 1 + extra_pins)) { |
| if (!list_empty(page_deferred_list(head))) { |
| ds_queue->split_queue_len--; |
| list_del(page_deferred_list(head)); |
| } |
| spin_unlock(&ds_queue->split_queue_lock); |
| if (mapping) { |
| int nr = thp_nr_pages(head); |
| |
| if (PageSwapBacked(head)) |
| __mod_lruvec_page_state(head, NR_SHMEM_THPS, |
| -nr); |
| else |
| __mod_lruvec_page_state(head, NR_FILE_THPS, |
| -nr); |
| } |
| |
| __split_huge_page(page, list, end); |
| ret = 0; |
| } else { |
| spin_unlock(&ds_queue->split_queue_lock); |
| fail: |
| if (mapping) |
| xa_unlock(&mapping->i_pages); |
| local_irq_enable(); |
| remap_page(head, thp_nr_pages(head)); |
| ret = -EBUSY; |
| } |
| |
| out_unlock: |
| if (anon_vma) { |
| anon_vma_unlock_write(anon_vma); |
| put_anon_vma(anon_vma); |
| } |
| if (mapping) |
| i_mmap_unlock_read(mapping); |
| out: |
| count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); |
| return ret; |
| } |
| |
| void free_transhuge_page(struct page *page) |
| { |
| struct deferred_split *ds_queue = get_deferred_split_queue(page); |
| unsigned long flags; |
| |
| spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
| if (!list_empty(page_deferred_list(page))) { |
| ds_queue->split_queue_len--; |
| list_del(page_deferred_list(page)); |
| } |
| spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); |
| free_compound_page(page); |
| } |
| |
| void deferred_split_huge_page(struct page *page) |
| { |
| struct deferred_split *ds_queue = get_deferred_split_queue(page); |
| #ifdef CONFIG_MEMCG |
| struct mem_cgroup *memcg = page_memcg(compound_head(page)); |
| #endif |
| unsigned long flags; |
| |
| VM_BUG_ON_PAGE(!PageTransHuge(page), page); |
| |
| /* |
| * The try_to_unmap() in page reclaim path might reach here too, |
| * this may cause a race condition to corrupt deferred split queue. |
| * And, if page reclaim is already handling the same page, it is |
| * unnecessary to handle it again in shrinker. |
| * |
| * Check PageSwapCache to determine if the page is being |
| * handled by page reclaim since THP swap would add the page into |
| * swap cache before calling try_to_unmap(). |
| */ |
| if (PageSwapCache(page)) |
| return; |
| |
| spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
| if (list_empty(page_deferred_list(page))) { |
| count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
| list_add_tail(page_deferred_list(page), &ds_queue->split_queue); |
| ds_queue->split_queue_len++; |
| #ifdef CONFIG_MEMCG |
| if (memcg) |
| set_shrinker_bit(memcg, page_to_nid(page), |
| 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 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), *pos, *next; |
| struct page *page; |
| int split = 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_safe(pos, next, &ds_queue->split_queue) { |
| page = list_entry((void *)pos, struct page, deferred_list); |
| page = compound_head(page); |
| if (get_page_unless_zero(page)) { |
| list_move(page_deferred_list(page), &list); |
| } else { |
| /* We lost race with put_compound_page() */ |
| list_del_init(page_deferred_list(page)); |
| ds_queue->split_queue_len--; |
| } |
| if (!--sc->nr_to_scan) |
| break; |
| } |
| spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); |
| |
| list_for_each_safe(pos, next, &list) { |
| page = list_entry((void *)pos, struct page, deferred_list); |
| if (!trylock_page(page)) |
| goto next; |
| /* split_huge_page() removes page from list on success */ |
| if (!split_huge_page(page)) |
| split++; |
| unlock_page(page); |
| next: |
| put_page(page); |
| } |
| |
| spin_lock_irqsave(&ds_queue->split_queue_lock, flags); |
| list_splice_tail(&list, &ds_queue->split_queue); |
| spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); |
| |
| /* |
| * 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; |
| } |
| |
| static struct shrinker deferred_split_shrinker = { |
| .count_objects = deferred_split_count, |
| .scan_objects = deferred_split_scan, |
| .seeks = DEFAULT_SEEKS, |
| .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | |
| SHRINKER_NONSLAB, |
| }; |
| |
| #ifdef CONFIG_DEBUG_FS |
| static void split_huge_pages_all(void) |
| { |
| struct zone *zone; |
| struct page *page; |
| unsigned long pfn, max_zone_pfn; |
| unsigned long total = 0, split = 0; |
| |
| pr_debug("Split all THPs\n"); |
| for_each_populated_zone(zone) { |
| max_zone_pfn = zone_end_pfn(zone); |
| for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { |
| if (!pfn_valid(pfn)) |
| continue; |
| |
| page = pfn_to_page(pfn); |
| if (!get_page_unless_zero(page)) |
| continue; |
| |
| if (zone != page_zone(page)) |
| goto next; |
| |
| if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) |
| goto next; |
| |
| total++; |
| lock_page(page); |
| if (!split_huge_page(page)) |
| split++; |
| unlock_page(page); |
| next: |
| put_page(page); |
| 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) |
| { |
| 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; |
| |
| /* Find the task_struct from pid */ |
| rcu_read_lock(); |
| task = find_task_by_vpid(pid); |
| if (!task) { |
| rcu_read_unlock(); |
| ret = -ESRCH; |
| goto out; |
| } |
| get_task_struct(task); |
| rcu_read_unlock(); |
| |
| /* 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 = find_vma(mm, addr); |
| unsigned int follflags; |
| struct page *page; |
| |
| if (!vma || addr < vma->vm_start) |
| break; |
| |
| /* skip special VMA and hugetlb VMA */ |
| if (vma_not_suitable_for_thp_split(vma)) { |
| addr = vma->vm_end; |
| continue; |
| } |
| |
| /* FOLL_DUMP to ignore special (like zero) pages */ |
| follflags = FOLL_GET | FOLL_DUMP; |
| page = follow_page(vma, addr, follflags); |
| |
| if (IS_ERR(page)) |
| continue; |
| if (!page) |
| continue; |
| |
| if (!is_transparent_hugepage(page)) |
| goto next; |
| |
| total++; |
| if (!can_split_huge_page(compound_head(page), NULL)) |
| goto next; |
| |
| if (!trylock_page(page)) |
| goto next; |
| |
| if (!split_huge_page(page)) |
| split++; |
| |
| unlock_page(page); |
| next: |
| put_page(page); |
| 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) |
| { |
| 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; |
| |
| 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; |
| |
| for (index = off_start; index < off_end; index += nr_pages) { |
| struct page *fpage = pagecache_get_page(mapping, index, |
| FGP_ENTRY | FGP_HEAD, 0); |
| |
| nr_pages = 1; |
| if (xa_is_value(fpage) || !fpage) |
| continue; |
| |
| if (!is_transparent_hugepage(fpage)) |
| goto next; |
| |
| total++; |
| nr_pages = thp_nr_pages(fpage); |
| |
| if (!trylock_page(fpage)) |
| goto next; |
| |
| if (!split_huge_page(fpage)) |
| split++; |
| |
| unlock_page(fpage); |
| next: |
| put_page(fpage); |
| 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 or file_path, off_start, off_end */ |
| char input_buf[MAX_INPUT_BUF_SZ]; |
| int pid; |
| unsigned long vaddr_start, vaddr_end; |
| |
| 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))) |
| |