| /* |
| * 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); |
| |
| #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; |
| |
| if (!khugepaged_enabled()) |
| return 0; |
| |
| 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; |
| } |
| late_initcall(set_recommended_min_free_kbytes); |
| |
| static int start_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; |
| } |
| |
| 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; |
| } |
| |
| return err; |
| } |
| |
| static atomic_t huge_zero_refcount; |
| static struct page *huge_zero_page __read_mostly; |
| |
| static inline bool is_huge_zero_page(struct page *page) |
| { |
| return ACCESS_ONCE(huge_zero_page) == page; |
| } |
| |
| 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 ACCESS_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 ACCESS_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_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) |
| return err; |
| |
| err = khugepaged_slab_init(); |
| if (err) |
| goto out; |
| |
| register_shrinker(&huge_zero_page_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; |
| |
| start_khugepaged(); |
| |
| return 0; |
| out: |
| hugepage_exit_sysfs(hugepage_kobj); |
| 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) |
| { |
| 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_TRANSHUGE, &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; |
| } |
| |
| static inline struct page *alloc_hugepage_vma(int defrag, |
| struct vm_area_struct *vma, |
| unsigned long haddr, int nd, |
| gfp_t extra_gfp) |
| { |
| return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp), |
| HPAGE_PMD_ORDER, vma, haddr, nd); |
| } |
| |
| /* 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) |
| { |
| 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; |
| } |
| page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
| vma, haddr, numa_node_id(), 0); |
| 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))) { |
| 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 */ |
| |
| 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()) |
| new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma), |
| vma, haddr, numa_node_id(), 0); |
| 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, |
| GFP_TRANSHUGE, &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_numa(*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_MLOCK) && (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; |
| int flags = 0; |
| |
| 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))) { |
| spin_unlock(ptl); |
| wait_migrate_huge_page(vma->anon_vma, pmdp); |
| 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; |
| } |
| |
| /* |
| * Avoid grouping on DSO/COW pages in specific and RO pages |
| * in general, RO pages shouldn't hurt as much anyway since |
| * they can be in shared cache state. |
| */ |
| if (!pmd_write(pmd)) |
| 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 pmd_numa cleared. |
| */ |
| 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; |
| } |
| |
| goto out; |
| clear_pmdnuma: |
| BUG_ON(!PageLocked(page)); |
| pmd = pmd_mknonnuma(pmd); |
| set_pmd_at(mm, haddr, pmdp, pmd); |
| VM_BUG_ON(pmd_numa(*pmdp)); |
| 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 mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| unsigned char *vec) |
| { |
| spinlock_t *ptl; |
| int ret = 0; |
| |
| if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) { |
| /* |
| * All logical pages in the range are present |
| * if backed by a huge page. |
| */ |
| spin_unlock(ptl); |
| memset(vec, 1, (end - addr) >> PAGE_SHIFT); |
| 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; |
| ret = 1; |
| if (!prot_numa) { |
| entry = pmdp_get_and_clear_notify(mm, addr, pmd); |
| if (pmd_numa(entry)) |
| entry = pmd_mknonnuma(entry); |
| entry = pmd_modify(entry, newprot); |
| ret = HPAGE_PMD_NR; |
| set_pmd_at(mm, addr, pmd, entry); |
| BUG_ON(pmd_write(entry)); |
| } else { |
| struct page *page = pmd_page(*pmd); |
| |
| /* |
| * Do not trap faults against the zero page. The |
| * read-only data is likely to be read-cached on the |
| * local CPU cache and it is less useful to know about |
| * local vs remote hits on the zero page. |
| */ |
| if (!is_huge_zero_page(page) && |
| !pmd_numa(*pmd)) { |
| pmdp_set_numa(mm, addr, pmd); |
| ret = HPAGE_PMD_NR; |
| } |
| } |
| 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 pmd_numa is not transferred deliberately |
| * to avoid any possibility that pte_numa leaks to |
| * a PROT_NONE VMA by accident. |
| */ |
| 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 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)) |
| 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 referenced = 0, none = 0; |
| for (_pte = pte; _pte < pte+HPAGE_PMD_NR; |
| _pte++, address += PAGE_SIZE) { |
| pte_t pteval = *_pte; |
| if (pte_none(pteval)) { |
| if (++none <= khugepaged_max_ptes_none) |
| continue; |
| else |
| goto out; |
| } |
| if (!pte_present(pteval) || !pte_write(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); |
| |
| /* cannot use mapcount: can't collapse if there's a gup pin */ |
| if (page_count(page) != 1) |
| goto out; |
| /* |
| * 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; |
| /* |
| * 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 = 1; |
| } |
| if (likely(referenced)) |
| 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)) { |
| clear_user_highpage(page, address); |
| add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); |
| } 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, 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, alloc_hugepage_gfpmask( |
| khugepaged_defrag(), __GFP_OTHER_NODE), 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, 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 */ |
| |
| VM_BUG_ON(address & ~HPAGE_PMD_MASK); |
| |
| /* release the mmap_sem read lock. */ |
| new_page = khugepaged_alloc_page(hpage, mm, vma, address, node); |
| if (!new_page) |
| return; |
| |
| if (unlikely(mem_cgroup_try_charge(new_page, mm, |
| GFP_TRANSHUGE, &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, referenced = 0, none = 0; |
| struct page *page; |
| unsigned long _address; |
| spinlock_t *ptl; |
| int node = NUMA_NO_NODE; |
| |
| 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)) { |
| if (++none <= khugepaged_max_ptes_none) |
| continue; |
| else |
| goto out_unmap; |
| } |
| if (!pte_present(pteval) || !pte_write(pteval)) |
| goto out_unmap; |
| 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 */ |
| if (page_count(page) != 1) |
| goto out_unmap; |
| if (pte_young(pteval) || PageReferenced(page) || |
| mmu_notifier_test_young(vma->vm_mm, address)) |
| referenced = 1; |
| } |
| if (referenced) |
| 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); |
| } |
| } |