--- /dev/null
+/*
+ * Copyright (C) 2009 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/sched.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/kthread.h>
+#include <linux/khugepaged.h>
+#include <linux/freezer.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/migrate.h>
+#include <linux/hashtable.h>
+
+#include <asm/tlb.h>
+#include <asm/pgalloc.h>
+#include "internal.h"
+
+/*
+ * By default transparent hugepage support is disabled in order that avoid
+ * to risk increase the memory footprint of applications without a guaranteed
+ * benefit. When transparent hugepage support is enabled, 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_FLAG)|
+ (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
+ (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+
+/* default scan 8*512 pte (or vmas) every 30 second */
+static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
+static unsigned int khugepaged_pages_collapsed;
+static unsigned int khugepaged_full_scans;
+static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
+/* during fragmentation poll the hugepage allocator once every minute */
+static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
+static struct task_struct *khugepaged_thread __read_mostly;
+static DEFINE_MUTEX(khugepaged_mutex);
+static DEFINE_SPINLOCK(khugepaged_mm_lock);
+static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
+/*
+ * default collapse hugepages if there is at least one pte mapped like
+ * it would have happened if the vma was large enough during page
+ * fault.
+ */
+static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
+
+static int khugepaged(void *none);
+static int khugepaged_slab_init(void);
+static void khugepaged_slab_exit(void);
+
+#define MM_SLOTS_HASH_BITS 10
+static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
+
+static struct kmem_cache *mm_slot_cache __read_mostly;
+
+/**
+ * struct mm_slot - hash lookup from mm to mm_slot
+ * @hash: hash collision list
+ * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
+ * @mm: the mm that this information is valid for
+ */
+struct mm_slot {
+ struct hlist_node hash;
+ struct list_head mm_node;
+ struct mm_struct *mm;
+};
+
+/**
+ * struct khugepaged_scan - cursor for scanning
+ * @mm_head: the head of the mm list to scan
+ * @mm_slot: the current mm_slot we are scanning
+ * @address: the next address inside that to be scanned
+ *
+ * There is only the one khugepaged_scan instance of this cursor structure.
+ */
+struct khugepaged_scan {
+ struct list_head mm_head;
+ struct mm_slot *mm_slot;
+ unsigned long address;
+};
+static struct khugepaged_scan khugepaged_scan = {
+ .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
+};
+
+
+static int set_recommended_min_free_kbytes(void)
+{
+ struct zone *zone;
+ int nr_zones = 0;
+ unsigned long recommended_min;
+
+ for_each_populated_zone(zone)
+ nr_zones++;
+
+ /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
+ recommended_min = pageblock_nr_pages * nr_zones * 2;
+
+ /*
+ * Make sure that on average at least two pageblocks are almost free
+ * of another type, one for a migratetype to fall back to and a
+ * second to avoid subsequent fallbacks of other types There are 3
+ * MIGRATE_TYPES we care about.
+ */
+ recommended_min += pageblock_nr_pages * nr_zones *
+ MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
+
+ /* don't ever allow to reserve more than 5% of the lowmem */
+ recommended_min = min(recommended_min,
+ (unsigned long) nr_free_buffer_pages() / 20);
+ recommended_min <<= (PAGE_SHIFT-10);
+
+ if (recommended_min > min_free_kbytes) {
+ if (user_min_free_kbytes >= 0)
+ pr_info("raising min_free_kbytes from %d to %lu "
+ "to help transparent hugepage allocations\n",
+ min_free_kbytes, recommended_min);
+
+ min_free_kbytes = recommended_min;
+ }
+ setup_per_zone_wmarks();
+ return 0;
+}
+
+static int start_stop_khugepaged(void)
+{
+ int err = 0;
+ if (khugepaged_enabled()) {
+ if (!khugepaged_thread)
+ khugepaged_thread = kthread_run(khugepaged, NULL,
+ "khugepaged");
+ if (unlikely(IS_ERR(khugepaged_thread))) {
+ pr_err("khugepaged: kthread_run(khugepaged) failed\n");
+ err = PTR_ERR(khugepaged_thread);
+ khugepaged_thread = NULL;
+ goto fail;
+ }
+
+ if (!list_empty(&khugepaged_scan.mm_head))
+ wake_up_interruptible(&khugepaged_wait);
+
+ set_recommended_min_free_kbytes();
+ } else if (khugepaged_thread) {
+ kthread_stop(khugepaged_thread);
+ khugepaged_thread = NULL;
+ }
+fail:
+ return err;
+}
+
+static atomic_t huge_zero_refcount;
+struct page *huge_zero_page __read_mostly;
+
+static inline bool is_huge_zero_pmd(pmd_t pmd)
+{
+ return is_huge_zero_page(pmd_page(pmd));
+}
+
+static struct page *get_huge_zero_page(void)
+{
+ struct page *zero_page;
+retry:
+ if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
+ return READ_ONCE(huge_zero_page);
+
+ 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 NULL;
+ }
+ 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;
+ }
+
+ /* We take additional reference here. It will be put back by shrinker */
+ atomic_set(&huge_zero_refcount, 2);
+ preempt_enable();
+ return READ_ONCE(huge_zero_page);
+}
+
+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));
+}
+
+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);
+ __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 double_flag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf,
+ enum transparent_hugepage_flag enabled,
+ enum transparent_hugepage_flag req_madv)
+{
+ if (test_bit(enabled, &transparent_hugepage_flags)) {
+ VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
+ return sprintf(buf, "[always] madvise never\n");
+ } else if (test_bit(req_madv, &transparent_hugepage_flags))
+ return sprintf(buf, "always [madvise] never\n");
+ else
+ return sprintf(buf, "always madvise [never]\n");
+}
+static ssize_t double_flag_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count,
+ enum transparent_hugepage_flag enabled,
+ enum transparent_hugepage_flag req_madv)
+{
+ if (!memcmp("always", buf,
+ min(sizeof("always")-1, count))) {
+ set_bit(enabled, &transparent_hugepage_flags);
+ clear_bit(req_madv, &transparent_hugepage_flags);
+ } else if (!memcmp("madvise", buf,
+ min(sizeof("madvise")-1, count))) {
+ clear_bit(enabled, &transparent_hugepage_flags);
+ set_bit(req_madv, &transparent_hugepage_flags);
+ } else if (!memcmp("never", buf,
+ min(sizeof("never")-1, count))) {
+ clear_bit(enabled, &transparent_hugepage_flags);
+ clear_bit(req_madv, &transparent_hugepage_flags);
+ } else
+ return -EINVAL;
+
+ return count;
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return double_flag_show(kobj, attr, buf,
+ TRANSPARENT_HUGEPAGE_FLAG,
+ TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+}
+static ssize_t enabled_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ ssize_t ret;
+
+ ret = double_flag_store(kobj, attr, buf, count,
+ TRANSPARENT_HUGEPAGE_FLAG,
+ TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+
+ if (ret > 0) {
+ int err;
+
+ mutex_lock(&khugepaged_mutex);
+ err = start_stop_khugepaged();
+ mutex_unlock(&khugepaged_mutex);
+
+ if (err)
+ ret = err;
+ }
+
+ return ret;
+}
+static struct kobj_attribute enabled_attr =
+ __ATTR(enabled, 0644, enabled_show, enabled_store);
+
+static ssize_t single_flag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf,
+ enum transparent_hugepage_flag flag)
+{
+ return sprintf(buf, "%d\n",
+ !!test_bit(flag, &transparent_hugepage_flags));
+}
+
+static ssize_t single_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;
+}
+
+/*
+ * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
+ * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
+ * memory just to allocate one more hugepage.
+ */
+static ssize_t defrag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return double_flag_show(kobj, attr, buf,
+ TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+ TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+static ssize_t defrag_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ return double_flag_store(kobj, attr, buf, count,
+ TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+ TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+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_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_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);
+#ifdef CONFIG_DEBUG_VM
+static ssize_t debug_cow_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return single_flag_show(kobj, attr, buf,
+ TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static ssize_t debug_cow_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ return single_flag_store(kobj, attr, buf, count,
+ TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static struct kobj_attribute debug_cow_attr =
+ __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
+#endif /* CONFIG_DEBUG_VM */
+
+static struct attribute *hugepage_attr[] = {
+ &enabled_attr.attr,
+ &defrag_attr.attr,
+ &use_zero_page_attr.attr,
+#ifdef CONFIG_DEBUG_VM
+ &debug_cow_attr.attr,
+#endif
+ NULL,
+};
+
+static struct attribute_group hugepage_attr_group = {
+ .attrs = hugepage_attr,
+};
+
+static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
+}
+
+static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long msecs;
+ int err;
+
+ err = kstrtoul(buf, 10, &msecs);
+ if (err || msecs > UINT_MAX)
+ return -EINVAL;
+
+ khugepaged_scan_sleep_millisecs = msecs;
+ wake_up_interruptible(&khugepaged_wait);
+
+ return count;
+}
+static struct kobj_attribute scan_sleep_millisecs_attr =
+ __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
+ scan_sleep_millisecs_store);
+
+static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
+}
+
+static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long msecs;
+ int err;
+
+ err = kstrtoul(buf, 10, &msecs);
+ if (err || msecs > UINT_MAX)
+ return -EINVAL;
+
+ khugepaged_alloc_sleep_millisecs = msecs;
+ wake_up_interruptible(&khugepaged_wait);
+
+ return count;
+}
+static struct kobj_attribute alloc_sleep_millisecs_attr =
+ __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
+ alloc_sleep_millisecs_store);
+
+static ssize_t pages_to_scan_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
+}
+static ssize_t pages_to_scan_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long pages;
+
+ err = kstrtoul(buf, 10, &pages);
+ if (err || !pages || pages > UINT_MAX)
+ return -EINVAL;
+
+ khugepaged_pages_to_scan = pages;
+
+ return count;
+}
+static struct kobj_attribute pages_to_scan_attr =
+ __ATTR(pages_to_scan, 0644, pages_to_scan_show,
+ pages_to_scan_store);
+
+static ssize_t pages_collapsed_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
+}
+static struct kobj_attribute pages_collapsed_attr =
+ __ATTR_RO(pages_collapsed);
+
+static ssize_t full_scans_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_full_scans);
+}
+static struct kobj_attribute full_scans_attr =
+ __ATTR_RO(full_scans);
+
+static ssize_t khugepaged_defrag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return single_flag_show(kobj, attr, buf,
+ TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static ssize_t khugepaged_defrag_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ return single_flag_store(kobj, attr, buf, count,
+ TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static struct kobj_attribute khugepaged_defrag_attr =
+ __ATTR(defrag, 0644, khugepaged_defrag_show,
+ khugepaged_defrag_store);
+
+/*
+ * max_ptes_none controls if khugepaged should collapse hugepages over
+ * any unmapped ptes in turn potentially increasing the memory
+ * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
+ * reduce the available free memory in the system as it
+ * runs. Increasing max_ptes_none will instead potentially reduce the
+ * free memory in the system during the khugepaged scan.
+ */
+static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
+}
+static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int err;
+ unsigned long max_ptes_none;
+
+ err = kstrtoul(buf, 10, &max_ptes_none);
+ if (err || max_ptes_none > HPAGE_PMD_NR-1)
+ return -EINVAL;
+
+ khugepaged_max_ptes_none = max_ptes_none;
+
+ return count;
+}
+static struct kobj_attribute khugepaged_max_ptes_none_attr =
+ __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
+ khugepaged_max_ptes_none_store);
+
+static struct attribute *khugepaged_attr[] = {
+ &khugepaged_defrag_attr.attr,
+ &khugepaged_max_ptes_none_attr.attr,
+ &pages_to_scan_attr.attr,
+ &pages_collapsed_attr.attr,
+ &full_scans_attr.attr,
+ &scan_sleep_millisecs_attr.attr,
+ &alloc_sleep_millisecs_attr.attr,
+ NULL,
+};
+
+static struct attribute_group khugepaged_attr_group = {
+ .attrs = khugepaged_attr,
+ .name = "khugepaged",
+};
+
+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()) {
+ transparent_hugepage_flags = 0;
+ return -EINVAL;
+ }
+
+ err = hugepage_init_sysfs(&hugepage_kobj);
+ if (err)
+ goto err_sysfs;
+
+ err = khugepaged_slab_init();
+ if (err)
+ goto err_slab;
+
+ err = register_shrinker(&huge_zero_page_shrinker);
+ if (err)
+ goto err_hzp_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(&huge_zero_page_shrinker);
+err_hzp_shrinker:
+ khugepaged_slab_exit();
+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;
+}
+
+static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
+{
+ pmd_t entry;
+ entry = mk_pmd(page, prot);
+ entry = pmd_mkhuge(entry);
+ return entry;
+}
+
+static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long haddr, pmd_t *pmd,
+ struct page *page, gfp_t gfp)
+{
+ struct mem_cgroup *memcg;
+ pgtable_t pgtable;
+ spinlock_t *ptl;
+
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
+
+ if (mem_cgroup_try_charge(page, mm, gfp, &memcg))
+ return VM_FAULT_OOM;
+
+ pgtable = pte_alloc_one(mm, haddr);
+ if (unlikely(!pgtable)) {
+ mem_cgroup_cancel_charge(page, memcg);
+ return VM_FAULT_OOM;
+ }
+
+ clear_huge_page(page, haddr, 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);
+
+ ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_none(*pmd))) {
+ spin_unlock(ptl);
+ mem_cgroup_cancel_charge(page, memcg);
+ put_page(page);
+ pte_free(mm, pgtable);
+ } else {
+ pmd_t entry;
+ 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);
+ mem_cgroup_commit_charge(page, memcg, false);
+ lru_cache_add_active_or_unevictable(page, vma);
+ pgtable_trans_huge_deposit(mm, pmd, pgtable);
+ set_pmd_at(mm, haddr, pmd, entry);
+ add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ atomic_long_inc(&mm->nr_ptes);
+ spin_unlock(ptl);
+ }
+
+ return 0;
+}
+
+static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
+{
+ return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
+}
+
+/* Caller must hold page table lock. */
+static bool 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 false;
+ entry = mk_pmd(zero_page, vma->vm_page_prot);
+ entry = pmd_mkhuge(entry);
+ pgtable_trans_huge_deposit(mm, pmd, pgtable);
+ set_pmd_at(mm, haddr, pmd, entry);
+ atomic_long_inc(&mm->nr_ptes);
+ return true;
+}
+
+int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmd,
+ unsigned int flags)
+{
+ gfp_t gfp;
+ struct page *page;
+ unsigned long haddr = address & HPAGE_PMD_MASK;
+
+ if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
+ 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 (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
+ transparent_hugepage_use_zero_page()) {
+ spinlock_t *ptl;
+ pgtable_t pgtable;
+ struct page *zero_page;
+ bool set;
+ pgtable = pte_alloc_one(mm, haddr);
+ if (unlikely(!pgtable))
+ return VM_FAULT_OOM;
+ zero_page = get_huge_zero_page();
+ if (unlikely(!zero_page)) {
+ pte_free(mm, pgtable);
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_FALLBACK;
+ }
+ ptl = pmd_lock(mm, pmd);
+ set = set_huge_zero_page(pgtable, mm, vma, haddr, pmd,
+ zero_page);
+ spin_unlock(ptl);
+ if (!set) {
+ pte_free(mm, pgtable);
+ put_huge_zero_page();
+ }
+ return 0;
+ }
+ gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
+ page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
+ if (unlikely(!page)) {
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_FALLBACK;
+ }
+ if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page, gfp))) {
+ put_page(page);
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_FALLBACK;
+ }
+
+ count_vm_event(THP_FAULT_ALLOC);
+ return 0;
+}
+
+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 *vma)
+{
+ spinlock_t *dst_ptl, *src_ptl;
+ struct page *src_page;
+ pmd_t pmd;
+ pgtable_t pgtable;
+ int ret;
+
+ ret = -ENOMEM;
+ pgtable = pte_alloc_one(dst_mm, addr);
+ if (unlikely(!pgtable))
+ goto out;
+
+ dst_ptl = pmd_lock(dst_mm, dst_pmd);
+ src_ptl = pmd_lockptr(src_mm, src_pmd);
+ spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+
+ ret = -EAGAIN;
+ pmd = *src_pmd;
+ if (unlikely(!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)) {
+ struct page *zero_page;
+ bool set;
+ /*
+ * 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.
+ */
+ zero_page = get_huge_zero_page();
+ set = set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
+ zero_page);
+ BUG_ON(!set); /* unexpected !pmd_none(dst_pmd) */
+ ret = 0;
+ goto out_unlock;
+ }
+
+ if (unlikely(pmd_trans_splitting(pmd))) {
+ /* split huge page running from under us */
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+ pte_free(dst_mm, pgtable);
+
+ wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
+ goto out;
+ }
+ src_page = pmd_page(pmd);
+ VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+ get_page(src_page);
+ page_dup_rmap(src_page);
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+
+ pmdp_set_wrprotect(src_mm, addr, src_pmd);
+ pmd = pmd_mkold(pmd_wrprotect(pmd));
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+ atomic_long_inc(&dst_mm->nr_ptes);
+
+ ret = 0;
+out_unlock:
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+out:
+ return ret;
+}
+
+void huge_pmd_set_accessed(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long address,
+ pmd_t *pmd, pmd_t orig_pmd,
+ int dirty)
+{
+ spinlock_t *ptl;
+ pmd_t entry;
+ unsigned long haddr;
+
+ ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_same(*pmd, orig_pmd)))
+ goto unlock;
+
+ entry = pmd_mkyoung(orig_pmd);
+ haddr = address & HPAGE_PMD_MASK;
+ if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
+ update_mmu_cache_pmd(vma, address, pmd);
+
+unlock:
+ spin_unlock(ptl);
+}
+
+/*
+ * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
+ * during copy_user_huge_page()'s copy_page_rep(): in the case when
+ * the source page gets split and a tail freed before copy completes.
+ * Called under pmd_lock of checked pmd, so safe from splitting itself.
+ */
+static void get_user_huge_page(struct page *page)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+ struct page *endpage = page + HPAGE_PMD_NR;
+
+ atomic_add(HPAGE_PMD_NR, &page->_count);
+ while (++page < endpage)
+ get_huge_page_tail(page);
+ } else {
+ get_page(page);
+ }
+}
+
+static void put_user_huge_page(struct page *page)
+{
+ if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
+ struct page *endpage = page + HPAGE_PMD_NR;
+
+ while (page < endpage)
+ put_page(page++);
+ } else {
+ put_page(page);
+ }
+}
+
+static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long address,
+ pmd_t *pmd, pmd_t orig_pmd,
+ struct page *page,
+ unsigned long haddr)
+{
+ struct mem_cgroup *memcg;
+ spinlock_t *ptl;
+ pgtable_t pgtable;
+ pmd_t _pmd;
+ int ret = 0, i;
+ struct page **pages;
+ unsigned long mmun_start; /* For mmu_notifiers */
+ unsigned long mmun_end; /* For mmu_notifiers */
+
+ pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
+ GFP_KERNEL);
+ if (unlikely(!pages)) {
+ ret |= VM_FAULT_OOM;
+ goto out;
+ }
+
+ for (i = 0; i < HPAGE_PMD_NR; i++) {
+ pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
+ __GFP_OTHER_NODE,
+ vma, address, page_to_nid(page));
+ if (unlikely(!pages[i] ||
+ mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
+ &memcg))) {
+ if (pages[i])
+ put_page(pages[i]);
+ while (--i >= 0) {
+ memcg = (void *)page_private(pages[i]);
+ set_page_private(pages[i], 0);
+ mem_cgroup_cancel_charge(pages[i], memcg);
+ put_page(pages[i]);
+ }
+ kfree(pages);
+ ret |= VM_FAULT_OOM;
+ goto out;
+ }
+ set_page_private(pages[i], (unsigned long)memcg);
+ }
+
+ for (i = 0; i < HPAGE_PMD_NR; i++) {
+ copy_user_highpage(pages[i], page + i,
+ haddr + PAGE_SIZE * i, vma);
+ __SetPageUptodate(pages[i]);
+ cond_resched();
+ }
+
+ mmun_start = haddr;
+ mmun_end = haddr + HPAGE_PMD_SIZE;
+ mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+ ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_same(*pmd, orig_pmd)))
+ goto out_free_pages;
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+
+ pmdp_clear_flush_notify(vma, haddr, pmd);
+ /* leave pmd empty until pte is filled */
+
+ 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 = mk_pte(pages[i], vma->vm_page_prot);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ memcg = (void *)page_private(pages[i]);
+ set_page_private(pages[i], 0);
+ page_add_new_anon_rmap(pages[i], vma, haddr);
+ mem_cgroup_commit_charge(pages[i], memcg, false);
+ lru_cache_add_active_or_unevictable(pages[i], vma);
+ pte = pte_offset_map(&_pmd, haddr);
+ VM_BUG_ON(!pte_none(*pte));
+ set_pte_at(mm, haddr, pte, entry);
+ pte_unmap(pte);
+ }
+ kfree(pages);
+
+ smp_wmb(); /* make pte visible before pmd */
+ pmd_populate(mm, pmd, pgtable);
+ page_remove_rmap(page);
+ spin_unlock(ptl);
+
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+ ret |= VM_FAULT_WRITE;
+ put_page(page);
+
+out:
+ return ret;
+
+out_free_pages:
+ spin_unlock(ptl);
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+ for (i = 0; i < HPAGE_PMD_NR; i++) {
+ memcg = (void *)page_private(pages[i]);
+ set_page_private(pages[i], 0);
+ mem_cgroup_cancel_charge(pages[i], memcg);
+ put_page(pages[i]);
+ }
+ kfree(pages);
+ goto out;
+}
+
+int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
+{
+ spinlock_t *ptl;
+ int ret = 0;
+ struct page *page = NULL, *new_page;
+ struct mem_cgroup *memcg;
+ unsigned long haddr;
+ unsigned long mmun_start; /* For mmu_notifiers */
+ unsigned long mmun_end; /* For mmu_notifiers */
+ gfp_t huge_gfp; /* for allocation and charge */
+
+ ptl = pmd_lockptr(mm, pmd);
+ VM_BUG_ON_VMA(!vma->anon_vma, vma);
+ haddr = address & HPAGE_PMD_MASK;
+ if (is_huge_zero_pmd(orig_pmd))
+ goto alloc;
+ spin_lock(ptl);
+ if (unlikely(!pmd_same(*pmd, orig_pmd)))
+ goto out_unlock;
+
+ page = pmd_page(orig_pmd);
+ VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
+ if (page_mapcount(page) == 1) {
+ pmd_t entry;
+ entry = pmd_mkyoung(orig_pmd);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
+ update_mmu_cache_pmd(vma, address, pmd);
+ ret |= VM_FAULT_WRITE;
+ goto out_unlock;
+ }
+ get_user_huge_page(page);
+ spin_unlock(ptl);
+alloc:
+ if (transparent_hugepage_enabled(vma) &&
+ !transparent_hugepage_debug_cow()) {
+ huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
+ new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
+ } else
+ new_page = NULL;
+
+ if (unlikely(!new_page)) {
+ if (!page) {
+ split_huge_page_pmd(vma, address, pmd);
+ ret |= VM_FAULT_FALLBACK;
+ } else {
+ ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
+ pmd, orig_pmd, page, haddr);
+ if (ret & VM_FAULT_OOM) {
+ split_huge_page(page);
+ ret |= VM_FAULT_FALLBACK;
+ }
+ put_user_huge_page(page);
+ }
+ count_vm_event(THP_FAULT_FALLBACK);
+ goto out;
+ }
+
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
+ put_page(new_page);
+ if (page) {
+ split_huge_page(page);
+ put_user_huge_page(page);
+ } else
+ split_huge_page_pmd(vma, address, pmd);
+ ret |= VM_FAULT_FALLBACK;
+ count_vm_event(THP_FAULT_FALLBACK);
+ goto out;
+ }
+
+ count_vm_event(THP_FAULT_ALLOC);
+
+ if (!page)
+ clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
+ else
+ copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
+ __SetPageUptodate(new_page);
+
+ mmun_start = haddr;
+ mmun_end = haddr + HPAGE_PMD_SIZE;
+ mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
+ spin_lock(ptl);
+ if (page)
+ put_user_huge_page(page);
+ if (unlikely(!pmd_same(*pmd, orig_pmd))) {
+ spin_unlock(ptl);
+ mem_cgroup_cancel_charge(new_page, memcg);
+ put_page(new_page);
+ goto out_mn;
+ } else {
+ pmd_t entry;
+ entry = mk_huge_pmd(new_page, vma->vm_page_prot);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ pmdp_clear_flush_notify(vma, haddr, pmd);
+ page_add_new_anon_rmap(new_page, vma, haddr);
+ mem_cgroup_commit_charge(new_page, memcg, false);
+ lru_cache_add_active_or_unevictable(new_page, vma);
+ set_pmd_at(mm, haddr, pmd, entry);
+ update_mmu_cache_pmd(vma, address, pmd);
+ if (!page) {
+ add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ put_huge_zero_page();
+ } else {
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ page_remove_rmap(page);
+ put_page(page);
+ }
+ ret |= VM_FAULT_WRITE;
+ }
+ spin_unlock(ptl);
+out_mn:
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out:
+ return ret;
+out_unlock:
+ spin_unlock(ptl);
+ return ret;
+}
+
+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 && !pmd_write(*pmd))
+ 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), page);
+ if (flags & FOLL_TOUCH) {
+ pmd_t _pmd;
+ /*
+ * We should set the dirty bit only for FOLL_WRITE but
+ * for now the dirty bit in the pmd is meaningless.
+ * And if the dirty bit will become meaningful and
+ * we'll only set it with FOLL_WRITE, an atomic
+ * set_bit will be required on the pmd to set the
+ * young bit, instead of the current set_pmd_at.
+ */
+ _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
+ if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
+ pmd, _pmd, 1))
+ update_mmu_cache_pmd(vma, addr, pmd);
+ }
+ if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) {
+ if (page->mapping && trylock_page(page)) {
+ lru_add_drain();
+ if (page->mapping)
+ mlock_vma_page(page);
+ unlock_page(page);
+ }
+ }
+ page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
+ if (flags & FOLL_GET)
+ get_page_foll(page);
+
+out:
+ return page;
+}
+
+/* NUMA hinting page fault entry point for trans huge pmds */
+int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, pmd_t pmd, pmd_t *pmdp)
+{
+ spinlock_t *ptl;
+ struct anon_vma *anon_vma = NULL;
+ struct page *page;
+ unsigned long haddr = addr & HPAGE_PMD_MASK;
+ int page_nid = -1, this_nid = numa_node_id();
+ int target_nid, last_cpupid = -1;
+ bool page_locked;
+ bool migrated = false;
+ bool was_writable;
+ int flags = 0;
+
+ /* A PROT_NONE fault should not end up here */
+ BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
+
+ ptl = pmd_lock(mm, pmdp);
+ if (unlikely(!pmd_same(pmd, *pmdp)))
+ goto out_unlock;
+
+ /*
+ * If there are potential migrations, wait for completion and retry
+ * without disrupting NUMA hinting information. Do not relock and
+ * check_same as the page may no longer be mapped.
+ */
+ if (unlikely(pmd_trans_migrating(*pmdp))) {
+ page = pmd_page(*pmdp);
+ spin_unlock(ptl);
+ wait_on_page_locked(page);
+ goto out;
+ }
+
+ page = pmd_page(pmd);
+ BUG_ON(is_huge_zero_page(page));
+ page_nid = page_to_nid(page);
+ last_cpupid = page_cpupid_last(page);
+ count_vm_numa_event(NUMA_HINT_FAULTS);
+ if (page_nid == this_nid) {
+ count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
+ flags |= TNF_FAULT_LOCAL;
+ }
+
+ /* See similar comment in do_numa_page for explanation */
+ if (!(vma->vm_flags & VM_WRITE))
+ flags |= TNF_NO_GROUP;
+
+ /*
+ * Acquire the page lock to serialise THP migrations but avoid dropping
+ * page_table_lock if at all possible
+ */
+ page_locked = trylock_page(page);
+ target_nid = mpol_misplaced(page, vma, haddr);
+ if (target_nid == -1) {
+ /* If the page was locked, there are no parallel migrations */
+ if (page_locked)
+ goto clear_pmdnuma;
+ }
+
+ /* Migration could have started since the pmd_trans_migrating check */
+ if (!page_locked) {
+ spin_unlock(ptl);
+ wait_on_page_locked(page);
+ page_nid = -1;
+ goto out;
+ }
+
+ /*
+ * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
+ * to serialises splits
+ */
+ get_page(page);
+ spin_unlock(ptl);
+ anon_vma = page_lock_anon_vma_read(page);
+
+ /* Confirm the PMD did not change while page_table_lock was released */
+ spin_lock(ptl);
+ if (unlikely(!pmd_same(pmd, *pmdp))) {
+ unlock_page(page);
+ put_page(page);
+ page_nid = -1;
+ goto out_unlock;
+ }
+
+ /* Bail if we fail to protect against THP splits for any reason */
+ if (unlikely(!anon_vma)) {
+ put_page(page);
+ page_nid = -1;
+ goto clear_pmdnuma;
+ }
+
+ /*
+ * Migrate the THP to the requested node, returns with page unlocked
+ * and access rights restored.
+ */
+ spin_unlock(ptl);
+ migrated = migrate_misplaced_transhuge_page(mm, vma,
+ pmdp, pmd, addr, page, target_nid);
+ if (migrated) {
+ flags |= TNF_MIGRATED;
+ page_nid = target_nid;
+ } else
+ flags |= TNF_MIGRATE_FAIL;
+
+ goto out;
+clear_pmdnuma:
+ BUG_ON(!PageLocked(page));
+ was_writable = pmd_write(pmd);
+ pmd = pmd_modify(pmd, vma->vm_page_prot);
+ pmd = pmd_mkyoung(pmd);
+ if (was_writable)
+ pmd = pmd_mkwrite(pmd);
+ set_pmd_at(mm, haddr, pmdp, pmd);
+ update_mmu_cache_pmd(vma, addr, pmdp);
+ unlock_page(page);
+out_unlock:
+ spin_unlock(ptl);
+
+out:
+ if (anon_vma)
+ page_unlock_anon_vma_read(anon_vma);
+
+ if (page_nid != -1)
+ task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
+
+ return 0;
+}
+
+int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ pmd_t *pmd, unsigned long addr)
+{
+ spinlock_t *ptl;
+ int ret = 0;
+
+ if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+ struct page *page;
+ pgtable_t pgtable;
+ pmd_t orig_pmd;
+ /*
+ * For architectures like ppc64 we look at deposited pgtable
+ * when calling pmdp_get_and_clear. So do the
+ * pgtable_trans_huge_withdraw after finishing pmdp related
+ * operations.
+ */
+ orig_pmd = pmdp_get_and_clear_full(tlb->mm, addr, pmd,
+ tlb->fullmm);
+ tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+ pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+ if (is_huge_zero_pmd(orig_pmd)) {
+ atomic_long_dec(&tlb->mm->nr_ptes);
+ spin_unlock(ptl);
+ put_huge_zero_page();
+ } else {
+ page = pmd_page(orig_pmd);
+ page_remove_rmap(page);
+ VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
+ add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ atomic_long_dec(&tlb->mm->nr_ptes);
+ spin_unlock(ptl);
+ tlb_remove_page(tlb, page);
+ }
+ pte_free(tlb->mm, pgtable);
+ ret = 1;
+ }
+ return ret;
+}
+
+int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
+ unsigned long old_addr,
+ unsigned long new_addr, unsigned long old_end,
+ pmd_t *old_pmd, pmd_t *new_pmd)
+{
+ spinlock_t *old_ptl, *new_ptl;
+ int ret = 0;
+ pmd_t pmd;
+
+ struct mm_struct *mm = vma->vm_mm;
+
+ if ((old_addr & ~HPAGE_PMD_MASK) ||
+ (new_addr & ~HPAGE_PMD_MASK) ||
+ old_end - old_addr < HPAGE_PMD_SIZE ||
+ (new_vma->vm_flags & VM_NOHUGEPAGE))
+ goto out;
+
+ /*
+ * 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));
+ goto out;
+ }
+
+ /*
+ * We don't have to worry about the ordering of src and dst
+ * ptlocks because exclusive mmap_sem prevents deadlock.
+ */
+ ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
+ if (ret == 1) {
+ new_ptl = pmd_lockptr(mm, new_pmd);
+ if (new_ptl != old_ptl)
+ spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
+ pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
+ VM_BUG_ON(!pmd_none(*new_pmd));
+
+ if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
+ pgtable_t pgtable;
+ pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+ pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+ }
+ set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
+ if (new_ptl != old_ptl)
+ spin_unlock(new_ptl);
+ spin_unlock(old_ptl);
+ }
+out:
+ return ret;
+}
+
+/*
+ * Returns
+ * - 0 if PMD could not be locked
+ * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
+ * - HPAGE_PMD_NR is protections changed and TLB flush necessary
+ */
+int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, pgprot_t newprot, int prot_numa)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ int ret = 0;
+
+ if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+ pmd_t entry;
+ bool preserve_write = prot_numa && pmd_write(*pmd);
+ ret = 1;
+
+ /*
+ * 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)) {
+ spin_unlock(ptl);
+ return ret;
+ }
+
+ if (!prot_numa || !pmd_protnone(*pmd)) {
+ entry = pmdp_get_and_clear_notify(mm, addr, pmd);
+ entry = pmd_modify(entry, newprot);
+ if (preserve_write)
+ entry = pmd_mkwrite(entry);
+ ret = HPAGE_PMD_NR;
+ set_pmd_at(mm, addr, pmd, entry);
+ BUG_ON(!preserve_write && pmd_write(entry));
+ }
+ spin_unlock(ptl);
+ }
+
+ return ret;
+}
+
+/*
+ * Returns 1 if a given pmd maps a stable (not under splitting) thp.
+ * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
+ *
+ * Note that if it returns 1, this routine returns without unlocking page
+ * table locks. So callers must unlock them.
+ */
+int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
+ spinlock_t **ptl)
+{
+ *ptl = pmd_lock(vma->vm_mm, pmd);
+ if (likely(pmd_trans_huge(*pmd))) {
+ if (unlikely(pmd_trans_splitting(*pmd))) {
+ spin_unlock(*ptl);
+ wait_split_huge_page(vma->anon_vma, pmd);
+ return -1;
+ } else {
+ /* Thp mapped by 'pmd' is stable, so we can
+ * handle it as it is. */
+ return 1;
+ }
+ }
+ spin_unlock(*ptl);
+ return 0;
+}
+
+/*
+ * This function returns whether a given @page is mapped onto the @address
+ * in the virtual space of @mm.
+ *
+ * When it's true, this function returns *pmd with holding the page table lock
+ * and passing it back to the caller via @ptl.
+ * If it's false, returns NULL without holding the page table lock.
+ */
+pmd_t *page_check_address_pmd(struct page *page,
+ struct mm_struct *mm,
+ unsigned long address,
+ enum page_check_address_pmd_flag flag,
+ spinlock_t **ptl)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ if (address & ~HPAGE_PMD_MASK)
+ return NULL;
+
+ pgd = pgd_offset(mm, address);
+ if (!pgd_present(*pgd))
+ return NULL;
+ pud = pud_offset(pgd, address);
+ if (!pud_present(*pud))
+ return NULL;
+ pmd = pmd_offset(pud, address);
+
+ *ptl = pmd_lock(mm, pmd);
+ if (!pmd_present(*pmd))
+ goto unlock;
+ if (pmd_page(*pmd) != page)
+ goto unlock;
+ /*
+ * split_vma() may create temporary aliased mappings. There is
+ * no risk as long as all huge pmd are found and have their
+ * splitting bit set before __split_huge_page_refcount
+ * runs. Finding the same huge pmd more than once during the
+ * same rmap walk is not a problem.
+ */
+ if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
+ pmd_trans_splitting(*pmd))
+ goto unlock;
+ if (pmd_trans_huge(*pmd)) {
+ VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
+ !pmd_trans_splitting(*pmd));
+ return pmd;
+ }
+unlock:
+ spin_unlock(*ptl);
+ return NULL;
+}
+
+static int __split_huge_page_splitting(struct page *page,
+ struct vm_area_struct *vma,
+ unsigned long address)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ pmd_t *pmd;
+ int ret = 0;
+ /* For mmu_notifiers */
+ const unsigned long mmun_start = address;
+ const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
+
+ mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+ pmd = page_check_address_pmd(page, mm, address,
+ PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
+ if (pmd) {
+ /*
+ * We can't temporarily set the pmd to null in order
+ * to split it, the pmd must remain marked huge at all
+ * times or the VM won't take the pmd_trans_huge paths
+ * and it won't wait on the anon_vma->root->rwsem to
+ * serialize against split_huge_page*.
+ */
+ pmdp_splitting_flush(vma, address, pmd);
+
+ ret = 1;
+ spin_unlock(ptl);
+ }
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+ return ret;
+}
+
+static void __split_huge_page_refcount(struct page *page,
+ struct list_head *list)
+{
+ int i;
+ struct zone *zone = page_zone(page);
+ struct lruvec *lruvec;
+ int tail_count = 0;
+
+ /* prevent PageLRU to go away from under us, and freeze lru stats */
+ spin_lock_irq(&zone->lru_lock);
+ lruvec = mem_cgroup_page_lruvec(page, zone);
+
+ compound_lock(page);
+ /* complete memcg works before add pages to LRU */
+ mem_cgroup_split_huge_fixup(page);
+
+ for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
+ struct page *page_tail = page + i;
+
+ /* tail_page->_mapcount cannot change */
+ BUG_ON(page_mapcount(page_tail) < 0);
+ tail_count += page_mapcount(page_tail);
+ /* check for overflow */
+ BUG_ON(tail_count < 0);
+ BUG_ON(atomic_read(&page_tail->_count) != 0);
+ /*
+ * tail_page->_count is zero and not changing from
+ * under us. But get_page_unless_zero() may be running
+ * from under us on the tail_page. If we used
+ * atomic_set() below instead of atomic_add(), we
+ * would then run atomic_set() concurrently with
+ * get_page_unless_zero(), and atomic_set() is
+ * implemented in C not using locked ops. spin_unlock
+ * on x86 sometime uses locked ops because of PPro
+ * errata 66, 92, so unless somebody can guarantee
+ * atomic_set() here would be safe on all archs (and
+ * not only on x86), it's safer to use atomic_add().
+ */
+ atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
+ &page_tail->_count);
+
+ /* after clearing PageTail the gup refcount can be released */
+ smp_mb__after_atomic();
+
+ /*
+ * retain hwpoison flag of the poisoned tail page:
+ * fix for the unsuitable process killed on Guest Machine(KVM)
+ * by the memory-failure.
+ */
+ page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
+ page_tail->flags |= (page->flags &
+ ((1L << PG_referenced) |
+ (1L << PG_swapbacked) |
+ (1L << PG_mlocked) |
+ (1L << PG_uptodate) |
+ (1L << PG_active) |
+ (1L << PG_unevictable)));
+ page_tail->flags |= (1L << PG_dirty);
+
+ /* clear PageTail before overwriting first_page */
+ smp_wmb();
+
+ /*
+ * __split_huge_page_splitting() already set the
+ * splitting bit in all pmd that could map this
+ * hugepage, that will ensure no CPU can alter the
+ * mapcount on the head page. The mapcount is only
+ * accounted in the head page and it has to be
+ * transferred to all tail pages in the below code. So
+ * for this code to be safe, the split the mapcount
+ * can't change. But that doesn't mean userland can't
+ * keep changing and reading the page contents while
+ * we transfer the mapcount, so the pmd splitting
+ * status is achieved setting a reserved bit in the
+ * pmd, not by clearing the present bit.
+ */
+ page_tail->_mapcount = page->_mapcount;
+
+ BUG_ON(page_tail->mapping);
+ page_tail->mapping = page->mapping;
+
+ page_tail->index = page->index + i;
+ page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
+
+ BUG_ON(!PageAnon(page_tail));
+ BUG_ON(!PageUptodate(page_tail));
+ BUG_ON(!PageDirty(page_tail));
+ BUG_ON(!PageSwapBacked(page_tail));
+
+ lru_add_page_tail(page, page_tail, lruvec, list);
+ }
+ atomic_sub(tail_count, &page->_count);
+ BUG_ON(atomic_read(&page->_count) <= 0);
+
+ __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
+
+ ClearPageCompound(page);
+ compound_unlock(page);
+ spin_unlock_irq(&zone->lru_lock);
+
+ for (i = 1; i < HPAGE_PMD_NR; i++) {
+ struct page *page_tail = page + i;
+ BUG_ON(page_count(page_tail) <= 0);
+ /*
+ * Tail pages 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(page_tail);
+ }
+
+ /*
+ * Only the head page (now become a regular page) is required
+ * to be pinned by the caller.
+ */
+ BUG_ON(page_count(page) <= 0);
+}
+
+static int __split_huge_page_map(struct page *page,
+ struct vm_area_struct *vma,
+ unsigned long address)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ pmd_t *pmd, _pmd;
+ int ret = 0, i;
+ pgtable_t pgtable;
+ unsigned long haddr;
+
+ pmd = page_check_address_pmd(page, mm, address,
+ PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
+ if (pmd) {
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pmd_populate(mm, &_pmd, pgtable);
+ if (pmd_write(*pmd))
+ BUG_ON(page_mapcount(page) != 1);
+
+ haddr = address;
+ for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+ pte_t *pte, entry;
+ BUG_ON(PageCompound(page+i));
+ /*
+ * Note that NUMA hinting access restrictions are not
+ * transferred to avoid any possibility of altering
+ * permissions across VMAs.
+ */
+ entry = mk_pte(page + i, vma->vm_page_prot);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ if (!pmd_write(*pmd))
+ entry = pte_wrprotect(entry);
+ if (!pmd_young(*pmd))
+ entry = pte_mkold(entry);
+ pte = pte_offset_map(&_pmd, haddr);
+ BUG_ON(!pte_none(*pte));
+ set_pte_at(mm, haddr, pte, entry);
+ pte_unmap(pte);
+ }
+
+ smp_wmb(); /* make pte visible before 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/us/Processor_TechDocs/41322.pdf,
+ * Erratum 383 on page 93. 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_tlb_range();" we first
+ * mark the current pmd notpresent (atomically because
+ * here the pmd_trans_huge and pmd_trans_splitting
+ * 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.
+ */
+ pmdp_invalidate(vma, address, pmd);
+ pmd_populate(mm, pmd, pgtable);
+ ret = 1;
+ spin_unlock(ptl);
+ }
+
+ return ret;
+}
+
+/* must be called with anon_vma->root->rwsem held */
+static void __split_huge_page(struct page *page,
+ struct anon_vma *anon_vma,
+ struct list_head *list)
+{
+ int mapcount, mapcount2;
+ pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+ struct anon_vma_chain *avc;
+
+ BUG_ON(!PageHead(page));
+ BUG_ON(PageTail(page));
+
+ mapcount = 0;
+ anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+ struct vm_area_struct *vma = avc->vma;
+ unsigned long addr = vma_address(page, vma);
+ BUG_ON(is_vma_temporary_stack(vma));
+ mapcount += __split_huge_page_splitting(page, vma, addr);
+ }
+ /*
+ * It is critical that new vmas are added to the tail of the
+ * anon_vma list. This guarantes that if copy_huge_pmd() runs
+ * and establishes a child pmd before
+ * __split_huge_page_splitting() freezes the parent pmd (so if
+ * we fail to prevent copy_huge_pmd() from running until the
+ * whole __split_huge_page() is complete), we will still see
+ * the newly established pmd of the child later during the
+ * walk, to be able to set it as pmd_trans_splitting too.
+ */
+ if (mapcount != page_mapcount(page)) {
+ pr_err("mapcount %d page_mapcount %d\n",
+ mapcount, page_mapcount(page));
+ BUG();
+ }
+
+ __split_huge_page_refcount(page, list);
+
+ mapcount2 = 0;
+ anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
+ struct vm_area_struct *vma = avc->vma;
+ unsigned long addr = vma_address(page, vma);
+ BUG_ON(is_vma_temporary_stack(vma));
+ mapcount2 += __split_huge_page_map(page, vma, addr);
+ }
+ if (mapcount != mapcount2) {
+ pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
+ mapcount, mapcount2, page_mapcount(page));
+ BUG();
+ }
+}
+
+/*
+ * Split a hugepage into normal pages. This doesn't change the position of head
+ * page. 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.
+ * Return 0 if the hugepage is split successfully otherwise return 1.
+ */
+int split_huge_page_to_list(struct page *page, struct list_head *list)
+{
+ struct anon_vma *anon_vma;
+ int ret = 1;
+
+ BUG_ON(is_huge_zero_page(page));
+ BUG_ON(!PageAnon(page));
+
+ /*
+ * The caller does not necessarily hold an mmap_sem 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(page);
+ if (!anon_vma)
+ goto out;
+ anon_vma_lock_write(anon_vma);
+
+ ret = 0;
+ if (!PageCompound(page))
+ goto out_unlock;
+
+ BUG_ON(!PageSwapBacked(page));
+ __split_huge_page(page, anon_vma, list);
+ count_vm_event(THP_SPLIT);
+
+ BUG_ON(PageCompound(page));
+out_unlock:
+ anon_vma_unlock_write(anon_vma);
+ put_anon_vma(anon_vma);
+out:
+ return ret;
+}
+
+#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
+
+int hugepage_madvise(struct vm_area_struct *vma,
+ unsigned long *vm_flags, int advice)
+{
+ switch (advice) {
+ case MADV_HUGEPAGE:
+#ifdef CONFIG_S390
+ /*
+ * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
+ * can't handle this properly after s390_enable_sie, so we simply
+ * ignore the madvise to prevent qemu from causing a SIGSEGV.
+ */
+ if (mm_has_pgste(vma->vm_mm))
+ return 0;
+#endif
+ /*
+ * Be somewhat over-protective like KSM for now!
+ */
+ if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
+ return -EINVAL;
+ *vm_flags &= ~VM_NOHUGEPAGE;
+ *vm_flags |= VM_HUGEPAGE;
+ /*
+ * If the vma become good for khugepaged to scan,
+ * register it here without waiting a page fault that
+ * may not happen any time soon.
+ */
+ if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
+ return -ENOMEM;
+ break;
+ case MADV_NOHUGEPAGE:
+ /*
+ * Be somewhat over-protective like KSM for now!
+ */
+ if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
+ return -EINVAL;
+ *vm_flags &= ~VM_HUGEPAGE;
+ *vm_flags |= VM_NOHUGEPAGE;
+ /*
+ * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
+ * this vma even if we leave the mm registered in khugepaged if
+ * it got registered before VM_NOHUGEPAGE was set.
+ */
+ break;
+ }
+
+ return 0;
+}
+
+static int __init khugepaged_slab_init(void)
+{
+ mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
+ sizeof(struct mm_slot),
+ __alignof__(struct mm_slot), 0, NULL);
+ if (!mm_slot_cache)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void __init khugepaged_slab_exit(void)
+{
+ kmem_cache_destroy(mm_slot_cache);
+}
+
+static inline struct mm_slot *alloc_mm_slot(void)
+{
+ if (!mm_slot_cache) /* initialization failed */
+ return NULL;
+ return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
+}
+
+static inline void free_mm_slot(struct mm_slot *mm_slot)
+{
+ kmem_cache_free(mm_slot_cache, mm_slot);
+}
+
+static struct mm_slot *get_mm_slot(struct mm_struct *mm)
+{
+ struct mm_slot *mm_slot;
+
+ hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
+ if (mm == mm_slot->mm)
+ return mm_slot;
+
+ return NULL;
+}
+
+static void insert_to_mm_slots_hash(struct mm_struct *mm,
+ struct mm_slot *mm_slot)
+{
+ mm_slot->mm = mm;
+ hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
+}
+
+static inline int khugepaged_test_exit(struct mm_struct *mm)
+{
+ return atomic_read(&mm->mm_users) == 0;
+}
+
+int __khugepaged_enter(struct mm_struct *mm)
+{
+ struct mm_slot *mm_slot;
+ int wakeup;
+
+ mm_slot = alloc_mm_slot();
+ if (!mm_slot)
+ return -ENOMEM;
+
+ /* __khugepaged_exit() must not run from under us */
+ VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
+ if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
+ free_mm_slot(mm_slot);
+ return 0;
+ }
+
+ spin_lock(&khugepaged_mm_lock);
+ insert_to_mm_slots_hash(mm, mm_slot);
+ /*
+ * Insert just behind the scanning cursor, to let the area settle
+ * down a little.
+ */
+ wakeup = list_empty(&khugepaged_scan.mm_head);
+ list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
+ spin_unlock(&khugepaged_mm_lock);
+
+ atomic_inc(&mm->mm_count);
+ if (wakeup)
+ wake_up_interruptible(&khugepaged_wait);
+
+ return 0;
+}
+
+int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
+ unsigned long vm_flags)
+{
+ unsigned long hstart, hend;
+ if (!vma->anon_vma)
+ /*
+ * Not yet faulted in so we will register later in the
+ * page fault if needed.
+ */
+ return 0;
+ if (vma->vm_ops)
+ /* khugepaged not yet working on file or special mappings */
+ return 0;
+ VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
+ hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+ hend = vma->vm_end & HPAGE_PMD_MASK;
+ if (hstart < hend)
+ return khugepaged_enter(vma, vm_flags);
+ return 0;
+}
+
+void __khugepaged_exit(struct mm_struct *mm)
+{
+ struct mm_slot *mm_slot;
+ int free = 0;
+
+ spin_lock(&khugepaged_mm_lock);
+ mm_slot = get_mm_slot(mm);
+ if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
+ hash_del(&mm_slot->hash);
+ list_del(&mm_slot->mm_node);
+ free = 1;
+ }
+ spin_unlock(&khugepaged_mm_lock);
+
+ if (free) {
+ clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+ free_mm_slot(mm_slot);
+ mmdrop(mm);
+ } else if (mm_slot) {
+ /*
+ * This is required to serialize against
+ * khugepaged_test_exit() (which is guaranteed to run
+ * under mmap sem read mode). Stop here (after we
+ * return all pagetables will be destroyed) until
+ * khugepaged has finished working on the pagetables
+ * under the mmap_sem.
+ */
+ down_write(&mm->mmap_sem);
+ up_write(&mm->mmap_sem);
+ }
+}
+
+static void release_pte_page(struct page *page)
+{
+ /* 0 stands for page_is_file_cache(page) == false */
+ dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
+ unlock_page(page);
+ putback_lru_page(page);
+}
+
+static void release_pte_pages(pte_t *pte, pte_t *_pte)
+{
+ while (--_pte >= pte) {
+ pte_t pteval = *_pte;
+ if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
+ release_pte_page(pte_page(pteval));
+ }
+}
+
+static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
+ unsigned long address,
+ pte_t *pte)
+{
+ struct page *page;
+ pte_t *_pte;
+ int none_or_zero = 0;
+ bool referenced = false, writable = false;
+ for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
+ _pte++, address += PAGE_SIZE) {
+ pte_t pteval = *_pte;
+ if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+ if (++none_or_zero <= khugepaged_max_ptes_none)
+ continue;
+ else
+ goto out;
+ }
+ if (!pte_present(pteval))
+ goto out;
+ page = vm_normal_page(vma, address, pteval);
+ if (unlikely(!page))
+ goto out;
+
+ VM_BUG_ON_PAGE(PageCompound(page), page);
+ VM_BUG_ON_PAGE(!PageAnon(page), page);
+ VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+ /*
+ * We can do it before isolate_lru_page because the
+ * page can't be freed from under us. NOTE: PG_lock
+ * is needed to serialize against split_huge_page
+ * when invoked from the VM.
+ */
+ if (!trylock_page(page))
+ goto out;
+
+ /*
+ * cannot use mapcount: can't collapse if there's a gup pin.
+ * The page must only be referenced by the scanned process
+ * and page swap cache.
+ */
+ if (page_count(page) != 1 + !!PageSwapCache(page)) {
+ unlock_page(page);
+ goto out;
+ }
+ if (pte_write(pteval)) {
+ writable = true;
+ } else {
+ if (PageSwapCache(page) && !reuse_swap_page(page)) {
+ unlock_page(page);
+ goto out;
+ }
+ /*
+ * Page is not in the swap cache. It can be collapsed
+ * into a THP.
+ */
+ }
+
+ /*
+ * Isolate the page to avoid collapsing an hugepage
+ * currently in use by the VM.
+ */
+ if (isolate_lru_page(page)) {
+ unlock_page(page);
+ goto out;
+ }
+ /* 0 stands for page_is_file_cache(page) == false */
+ inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(PageLRU(page), page);
+
+ /* If there is no mapped pte young don't collapse the page */
+ if (pte_young(pteval) || PageReferenced(page) ||
+ mmu_notifier_test_young(vma->vm_mm, address))
+ referenced = true;
+ }
+ if (likely(referenced && writable))
+ return 1;
+out:
+ release_pte_pages(pte, _pte);
+ return 0;
+}
+
+static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
+ struct vm_area_struct *vma,
+ unsigned long address,
+ spinlock_t *ptl)
+{
+ pte_t *_pte;
+ for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
+ pte_t pteval = *_pte;
+ struct page *src_page;
+
+ if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+ clear_user_highpage(page, address);
+ add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
+ if (is_zero_pfn(pte_pfn(pteval))) {
+ /*
+ * ptl mostly unnecessary.
+ */
+ spin_lock(ptl);
+ /*
+ * paravirt calls inside pte_clear here are
+ * superfluous.
+ */
+ pte_clear(vma->vm_mm, address, _pte);
+ spin_unlock(ptl);
+ }
+ } else {
+ src_page = pte_page(pteval);
+ copy_user_highpage(page, src_page, address, vma);
+ VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
+ release_pte_page(src_page);
+ /*
+ * ptl mostly unnecessary, but preempt has to
+ * be disabled to update the per-cpu stats
+ * inside page_remove_rmap().
+ */
+ spin_lock(ptl);
+ /*
+ * paravirt calls inside pte_clear here are
+ * superfluous.
+ */
+ pte_clear(vma->vm_mm, address, _pte);
+ page_remove_rmap(src_page);
+ spin_unlock(ptl);
+ free_page_and_swap_cache(src_page);
+ }
+
+ address += PAGE_SIZE;
+ page++;
+ }
+}
+
+static void khugepaged_alloc_sleep(void)
+{
+ wait_event_freezable_timeout(khugepaged_wait, false,
+ msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
+}
+
+static int khugepaged_node_load[MAX_NUMNODES];
+
+static bool khugepaged_scan_abort(int nid)
+{
+ int i;
+
+ /*
+ * If zone_reclaim_mode is disabled, then no extra effort is made to
+ * allocate memory locally.
+ */
+ if (!zone_reclaim_mode)
+ return false;
+
+ /* If there is a count for this node already, it must be acceptable */
+ if (khugepaged_node_load[nid])
+ return false;
+
+ for (i = 0; i < MAX_NUMNODES; i++) {
+ if (!khugepaged_node_load[i])
+ continue;
+ if (node_distance(nid, i) > RECLAIM_DISTANCE)
+ return true;
+ }
+ return false;
+}
+
+#ifdef CONFIG_NUMA
+static int khugepaged_find_target_node(void)
+{
+ static int last_khugepaged_target_node = NUMA_NO_NODE;
+ int nid, target_node = 0, max_value = 0;
+
+ /* find first node with max normal pages hit */
+ for (nid = 0; nid < MAX_NUMNODES; nid++)
+ if (khugepaged_node_load[nid] > max_value) {
+ max_value = khugepaged_node_load[nid];
+ target_node = nid;
+ }
+
+ /* do some balance if several nodes have the same hit record */
+ if (target_node <= last_khugepaged_target_node)
+ for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
+ nid++)
+ if (max_value == khugepaged_node_load[nid]) {
+ target_node = nid;
+ break;
+ }
+
+ last_khugepaged_target_node = target_node;
+ return target_node;
+}
+
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+ if (IS_ERR(*hpage)) {
+ if (!*wait)
+ return false;
+
+ *wait = false;
+ *hpage = NULL;
+ khugepaged_alloc_sleep();
+ } else if (*hpage) {
+ put_page(*hpage);
+ *hpage = NULL;
+ }
+
+ return true;
+}
+
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
+ struct vm_area_struct *vma, unsigned long address,
+ int node)
+{
+ VM_BUG_ON_PAGE(*hpage, *hpage);
+
+ /*
+ * Before allocating the hugepage, release the mmap_sem read lock.
+ * The allocation can take potentially a long time if it involves
+ * sync compaction, and we do not need to hold the mmap_sem during
+ * that. We will recheck the vma after taking it again in write mode.
+ */
+ up_read(&mm->mmap_sem);
+
+ *hpage = alloc_pages_exact_node(node, gfp, HPAGE_PMD_ORDER);
+ if (unlikely(!*hpage)) {
+ count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
+ *hpage = ERR_PTR(-ENOMEM);
+ return NULL;
+ }
+
+ count_vm_event(THP_COLLAPSE_ALLOC);
+ return *hpage;
+}
+#else
+static int khugepaged_find_target_node(void)
+{
+ return 0;
+}
+
+static inline struct page *alloc_hugepage(int defrag)
+{
+ return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
+ HPAGE_PMD_ORDER);
+}
+
+static struct page *khugepaged_alloc_hugepage(bool *wait)
+{
+ struct page *hpage;
+
+ do {
+ hpage = alloc_hugepage(khugepaged_defrag());
+ if (!hpage) {
+ count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
+ if (!*wait)
+ return NULL;
+
+ *wait = false;
+ khugepaged_alloc_sleep();
+ } else
+ count_vm_event(THP_COLLAPSE_ALLOC);
+ } while (unlikely(!hpage) && likely(khugepaged_enabled()));
+
+ return hpage;
+}
+
+static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
+{
+ if (!*hpage)
+ *hpage = khugepaged_alloc_hugepage(wait);
+
+ if (unlikely(!*hpage))
+ return false;
+
+ return true;
+}
+
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
+ struct vm_area_struct *vma, unsigned long address,
+ int node)
+{
+ up_read(&mm->mmap_sem);
+ VM_BUG_ON(!*hpage);
+
+ return *hpage;
+}
+#endif
+
+static bool hugepage_vma_check(struct vm_area_struct *vma)
+{
+ if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
+ (vma->vm_flags & VM_NOHUGEPAGE))
+ return false;
+
+ if (!vma->anon_vma || vma->vm_ops)
+ return false;
+ if (is_vma_temporary_stack(vma))
+ return false;
+ VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
+ return true;
+}
+
+static void collapse_huge_page(struct mm_struct *mm,
+ unsigned long address,
+ struct page **hpage,
+ struct vm_area_struct *vma,
+ int node)
+{
+ pmd_t *pmd, _pmd;
+ pte_t *pte;
+ pgtable_t pgtable;
+ struct page *new_page;
+ spinlock_t *pmd_ptl, *pte_ptl;
+ int isolated;
+ unsigned long hstart, hend;
+ struct mem_cgroup *memcg;
+ unsigned long mmun_start; /* For mmu_notifiers */
+ unsigned long mmun_end; /* For mmu_notifiers */
+ gfp_t gfp;
+
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+ /* Only allocate from the target node */
+ gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
+ __GFP_THISNODE;
+
+ /* release the mmap_sem read lock. */
+ new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node);
+ if (!new_page)
+ return;
+
+ if (unlikely(mem_cgroup_try_charge(new_page, mm,
+ gfp, &memcg)))
+ return;
+
+ /*
+ * Prevent all access to pagetables with the exception of
+ * gup_fast later hanlded by the ptep_clear_flush and the VM
+ * handled by the anon_vma lock + PG_lock.
+ */
+ down_write(&mm->mmap_sem);
+ if (unlikely(khugepaged_test_exit(mm)))
+ goto out;
+
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto out;
+ hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+ hend = vma->vm_end & HPAGE_PMD_MASK;
+ if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+ goto out;
+ if (!hugepage_vma_check(vma))
+ goto out;
+ pmd = mm_find_pmd(mm, address);
+ if (!pmd)
+ goto out;
+
+ anon_vma_lock_write(vma->anon_vma);
+
+ pte = pte_offset_map(pmd, address);
+ pte_ptl = pte_lockptr(mm, pmd);
+
+ mmun_start = address;
+ mmun_end = address + HPAGE_PMD_SIZE;
+ mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+ pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
+ /*
+ * After this gup_fast can't run anymore. This also removes
+ * any huge TLB entry from the CPU so we won't allow
+ * huge and small TLB entries for the same virtual address
+ * to avoid the risk of CPU bugs in that area.
+ */
+ _pmd = pmdp_clear_flush(vma, address, pmd);
+ spin_unlock(pmd_ptl);
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+ spin_lock(pte_ptl);
+ isolated = __collapse_huge_page_isolate(vma, address, pte);
+ spin_unlock(pte_ptl);
+
+ if (unlikely(!isolated)) {
+ pte_unmap(pte);
+ spin_lock(pmd_ptl);
+ BUG_ON(!pmd_none(*pmd));
+ /*
+ * We can only use set_pmd_at when establishing
+ * hugepmds and never for establishing regular pmds that
+ * points to regular pagetables. Use pmd_populate for that
+ */
+ pmd_populate(mm, pmd, pmd_pgtable(_pmd));
+ spin_unlock(pmd_ptl);
+ anon_vma_unlock_write(vma->anon_vma);
+ goto out;
+ }
+
+ /*
+ * All pages are isolated and locked so anon_vma rmap
+ * can't run anymore.
+ */
+ anon_vma_unlock_write(vma->anon_vma);
+
+ __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
+ pte_unmap(pte);
+ __SetPageUptodate(new_page);
+ pgtable = pmd_pgtable(_pmd);
+
+ _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
+ _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
+
+ /*
+ * spin_lock() below is not the equivalent of smp_wmb(), so
+ * this is needed to avoid the copy_huge_page writes to become
+ * visible after the set_pmd_at() write.
+ */
+ smp_wmb();
+
+ spin_lock(pmd_ptl);
+ BUG_ON(!pmd_none(*pmd));
+ page_add_new_anon_rmap(new_page, vma, address);
+ mem_cgroup_commit_charge(new_page, memcg, false);
+ lru_cache_add_active_or_unevictable(new_page, vma);
+ pgtable_trans_huge_deposit(mm, pmd, pgtable);
+ set_pmd_at(mm, address, pmd, _pmd);
+ update_mmu_cache_pmd(vma, address, pmd);
+ spin_unlock(pmd_ptl);
+
+ *hpage = NULL;
+
+ khugepaged_pages_collapsed++;
+out_up_write:
+ up_write(&mm->mmap_sem);
+ return;
+
+out:
+ mem_cgroup_cancel_charge(new_page, memcg);
+ goto out_up_write;
+}
+
+static int khugepaged_scan_pmd(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ unsigned long address,
+ struct page **hpage)
+{
+ pmd_t *pmd;
+ pte_t *pte, *_pte;
+ int ret = 0, none_or_zero = 0;
+ struct page *page;
+ unsigned long _address;
+ spinlock_t *ptl;
+ int node = NUMA_NO_NODE;
+ bool writable = false, referenced = false;
+
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+ pmd = mm_find_pmd(mm, address);
+ if (!pmd)
+ goto out;
+
+ memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
+ pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+ for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
+ _pte++, _address += PAGE_SIZE) {
+ pte_t pteval = *_pte;
+ if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+ if (++none_or_zero <= khugepaged_max_ptes_none)
+ continue;
+ else
+ goto out_unmap;
+ }
+ if (!pte_present(pteval))
+ goto out_unmap;
+ if (pte_write(pteval))
+ writable = true;
+
+ page = vm_normal_page(vma, _address, pteval);
+ if (unlikely(!page))
+ goto out_unmap;
+ /*
+ * Record which node the original page is from and save this
+ * information to khugepaged_node_load[].
+ * Khupaged will allocate hugepage from the node has the max
+ * hit record.
+ */
+ node = page_to_nid(page);
+ if (khugepaged_scan_abort(node))
+ goto out_unmap;
+ khugepaged_node_load[node]++;
+ VM_BUG_ON_PAGE(PageCompound(page), page);
+ if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
+ goto out_unmap;
+ /*
+ * cannot use mapcount: can't collapse if there's a gup pin.
+ * The page must only be referenced by the scanned process
+ * and page swap cache.
+ */
+ if (page_count(page) != 1 + !!PageSwapCache(page))
+ goto out_unmap;
+ if (pte_young(pteval) || PageReferenced(page) ||
+ mmu_notifier_test_young(vma->vm_mm, address))
+ referenced = true;
+ }
+ if (referenced && writable)
+ ret = 1;
+out_unmap:
+ pte_unmap_unlock(pte, ptl);
+ if (ret) {
+ node = khugepaged_find_target_node();
+ /* collapse_huge_page will return with the mmap_sem released */
+ collapse_huge_page(mm, address, hpage, vma, node);
+ }
+out:
+ return ret;
+}
+
+static void collect_mm_slot(struct mm_slot *mm_slot)
+{
+ struct mm_struct *mm = mm_slot->mm;
+
+ VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
+
+ if (khugepaged_test_exit(mm)) {
+ /* free mm_slot */
+ hash_del(&mm_slot->hash);
+ list_del(&mm_slot->mm_node);
+
+ /*
+ * Not strictly needed because the mm exited already.
+ *
+ * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+ */
+
+ /* khugepaged_mm_lock actually not necessary for the below */
+ free_mm_slot(mm_slot);
+ mmdrop(mm);
+ }
+}
+
+static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
+ struct page **hpage)
+ __releases(&khugepaged_mm_lock)
+ __acquires(&khugepaged_mm_lock)
+{
+ struct mm_slot *mm_slot;
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ int progress = 0;
+
+ VM_BUG_ON(!pages);
+ VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
+
+ if (khugepaged_scan.mm_slot)
+ mm_slot = khugepaged_scan.mm_slot;
+ else {
+ mm_slot = list_entry(khugepaged_scan.mm_head.next,
+ struct mm_slot, mm_node);
+ khugepaged_scan.address = 0;
+ khugepaged_scan.mm_slot = mm_slot;
+ }
+ spin_unlock(&khugepaged_mm_lock);
+
+ mm = mm_slot->mm;
+ down_read(&mm->mmap_sem);
+ if (unlikely(khugepaged_test_exit(mm)))
+ vma = NULL;
+ else
+ vma = find_vma(mm, khugepaged_scan.address);
+
+ progress++;
+ for (; vma; vma = vma->vm_next) {
+ unsigned long hstart, hend;
+
+ cond_resched();
+ if (unlikely(khugepaged_test_exit(mm))) {
+ progress++;
+ break;
+ }
+ if (!hugepage_vma_check(vma)) {
+skip:
+ progress++;
+ continue;
+ }
+ hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+ hend = vma->vm_end & HPAGE_PMD_MASK;
+ if (hstart >= hend)
+ goto skip;
+ if (khugepaged_scan.address > hend)
+ goto skip;
+ if (khugepaged_scan.address < hstart)
+ khugepaged_scan.address = hstart;
+ VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
+
+ while (khugepaged_scan.address < hend) {
+ int ret;
+ cond_resched();
+ if (unlikely(khugepaged_test_exit(mm)))
+ goto breakouterloop;
+
+ VM_BUG_ON(khugepaged_scan.address < hstart ||
+ khugepaged_scan.address + HPAGE_PMD_SIZE >
+ hend);
+ ret = khugepaged_scan_pmd(mm, vma,
+ khugepaged_scan.address,
+ hpage);
+ /* move to next address */
+ khugepaged_scan.address += HPAGE_PMD_SIZE;
+ progress += HPAGE_PMD_NR;
+ if (ret)
+ /* we released mmap_sem so break loop */
+ goto breakouterloop_mmap_sem;
+ if (progress >= pages)
+ goto breakouterloop;
+ }
+ }
+breakouterloop:
+ up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
+breakouterloop_mmap_sem:
+
+ spin_lock(&khugepaged_mm_lock);
+ VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
+ /*
+ * Release the current mm_slot if this mm is about to die, or
+ * if we scanned all vmas of this mm.
+ */
+ if (khugepaged_test_exit(mm) || !vma) {
+ /*
+ * Make sure that if mm_users is reaching zero while
+ * khugepaged runs here, khugepaged_exit will find
+ * mm_slot not pointing to the exiting mm.
+ */
+ if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
+ khugepaged_scan.mm_slot = list_entry(
+ mm_slot->mm_node.next,
+ struct mm_slot, mm_node);
+ khugepaged_scan.address = 0;
+ } else {
+ khugepaged_scan.mm_slot = NULL;
+ khugepaged_full_scans++;
+ }
+
+ collect_mm_slot(mm_slot);
+ }
+
+ return progress;
+}
+
+static int khugepaged_has_work(void)
+{
+ return !list_empty(&khugepaged_scan.mm_head) &&
+ khugepaged_enabled();
+}
+
+static int khugepaged_wait_event(void)
+{
+ return !list_empty(&khugepaged_scan.mm_head) ||
+ kthread_should_stop();
+}
+
+static void khugepaged_do_scan(void)
+{
+ struct page *hpage = NULL;
+ unsigned int progress = 0, pass_through_head = 0;
+ unsigned int pages = khugepaged_pages_to_scan;
+ bool wait = true;
+
+ barrier(); /* write khugepaged_pages_to_scan to local stack */
+
+ while (progress < pages) {
+ if (!khugepaged_prealloc_page(&hpage, &wait))
+ break;
+
+ cond_resched();
+
+ if (unlikely(kthread_should_stop() || freezing(current)))
+ break;
+
+ spin_lock(&khugepaged_mm_lock);
+ if (!khugepaged_scan.mm_slot)
+ pass_through_head++;
+ if (khugepaged_has_work() &&
+ pass_through_head < 2)
+ progress += khugepaged_scan_mm_slot(pages - progress,
+ &hpage);
+ else
+ progress = pages;
+ spin_unlock(&khugepaged_mm_lock);
+ }
+
+ if (!IS_ERR_OR_NULL(hpage))
+ put_page(hpage);
+}
+
+static void khugepaged_wait_work(void)
+{
+ try_to_freeze();
+
+ if (khugepaged_has_work()) {
+ if (!khugepaged_scan_sleep_millisecs)
+ return;
+
+ wait_event_freezable_timeout(khugepaged_wait,
+ kthread_should_stop(),
+ msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
+ return;
+ }
+
+ if (khugepaged_enabled())
+ wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
+}
+
+static int khugepaged(void *none)
+{
+ struct mm_slot *mm_slot;
+
+ set_freezable();
+ set_user_nice(current, MAX_NICE);
+
+ while (!kthread_should_stop()) {
+ khugepaged_do_scan();
+ khugepaged_wait_work();
+ }
+
+ spin_lock(&khugepaged_mm_lock);
+ mm_slot = khugepaged_scan.mm_slot;
+ khugepaged_scan.mm_slot = NULL;
+ if (mm_slot)
+ collect_mm_slot(mm_slot);
+ spin_unlock(&khugepaged_mm_lock);
+ return 0;
+}
+
+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;
+
+ pmdp_clear_flush_notify(vma, haddr, pmd);
+ /* leave pmd empty until pte is filled */
+
+ 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);
+ put_huge_zero_page();
+}
+
+void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmd)
+{
+ spinlock_t *ptl;
+ struct page *page;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long haddr = address & HPAGE_PMD_MASK;
+ unsigned long mmun_start; /* For mmu_notifiers */
+ unsigned long mmun_end; /* For mmu_notifiers */
+
+ BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
+
+ mmun_start = haddr;
+ mmun_end = haddr + HPAGE_PMD_SIZE;
+again:
+ mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+ ptl = pmd_lock(mm, pmd);
+ if (unlikely(!pmd_trans_huge(*pmd))) {
+ spin_unlock(ptl);
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+ return;
+ }
+ if (is_huge_zero_pmd(*pmd)) {
+ __split_huge_zero_page_pmd(vma, haddr, pmd);
+ spin_unlock(ptl);
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+ return;
+ }
+ page = pmd_page(*pmd);
+ VM_BUG_ON_PAGE(!page_count(page), page);
+ get_page(page);
+ spin_unlock(ptl);
+ mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+ split_huge_page(page);
+
+ put_page(page);
+
+ /*
+ * We don't always have down_write of mmap_sem here: a racing
+ * do_huge_pmd_wp_page() might have copied-on-write to another
+ * huge page before our split_huge_page() got the anon_vma lock.
+ */
+ if (unlikely(pmd_trans_huge(*pmd)))
+ goto again;
+}
+
+void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
+ pmd_t *pmd)
+{
+ struct vm_area_struct *vma;
+
+ vma = find_vma(mm, address);
+ BUG_ON(vma == NULL);
+ split_huge_page_pmd(vma, address, pmd);
+}
+
+static void split_huge_page_address(struct mm_struct *mm,
+ unsigned long address)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
+
+ pgd = pgd_offset(mm, address);
+ if (!pgd_present(*pgd))
+ return;
+
+ pud = pud_offset(pgd, address);
+ if (!pud_present(*pud))
+ return;
+
+ pmd = pmd_offset(pud, address);
+ if (!pmd_present(*pmd))
+ return;
+ /*
+ * Caller holds the mmap_sem write mode, so a huge pmd cannot
+ * materialize from under us.
+ */
+ split_huge_page_pmd_mm(mm, address, pmd);
+}
+
+void __vma_adjust_trans_huge(struct vm_area_struct *vma,
+ unsigned long start,
+ unsigned long end,
+ long adjust_next)
+{
+ /*
+ * If the new start address isn't hpage aligned and it could
+ * previously contain an hugepage: check if we need to split
+ * an huge pmd.
+ */
+ if (start & ~HPAGE_PMD_MASK &&
+ (start & HPAGE_PMD_MASK) >= vma->vm_start &&
+ (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
+ split_huge_page_address(vma->vm_mm, start);
+
+ /*
+ * If the new end address isn't hpage aligned and it could
+ * previously contain an hugepage: check if we need to split
+ * an huge pmd.
+ */
+ if (end & ~HPAGE_PMD_MASK &&
+ (end & HPAGE_PMD_MASK) >= vma->vm_start &&
+ (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
+ split_huge_page_address(vma->vm_mm, end);
+
+ /*
+ * If we're also updating the vma->vm_next->vm_start, if the new
+ * vm_next->vm_start isn't page aligned and it could previously
+ * contain an hugepage: check if we need to split an huge pmd.
+ */
+ if (adjust_next > 0) {
+ struct vm_area_struct *next = vma->vm_next;
+ unsigned long nstart = next->vm_start;
+ nstart += adjust_next << PAGE_SHIFT;
+ if (nstart & ~HPAGE_PMD_MASK &&
+ (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
+ (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
+ split_huge_page_address(next->vm_mm, nstart);
+ }
+}
Code Review / kvmfornfv.git / blobdiff