b9980cdcf2
Fix CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_SMP=n CONFIG_DEBUG_VM=y CONFIG_DEBUG_SPINLOCK=n kernel: spin_is_locked() is then always false, and so triggers some BUGs in Transparent HugePage codepaths. asm-generic/bug.h mentions this problem, and provides a WARN_ON_SMP(x); but being too lazy to add VM_BUG_ON_SMP, BUG_ON_SMP, WARN_ON_SMP_ONCE, VM_WARN_ON_SMP_ONCE, just test NR_CPUS != 1 in the existing VM_BUG_ONs. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2463 lines
64 KiB
C
2463 lines
64 KiB
C
/*
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* Copyright (C) 2009 Red Hat, Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/highmem.h>
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#include <linux/hugetlb.h>
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#include <linux/mmu_notifier.h>
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#include <linux/rmap.h>
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#include <linux/swap.h>
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#include <linux/mm_inline.h>
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#include <linux/kthread.h>
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#include <linux/khugepaged.h>
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#include <linux/freezer.h>
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#include <linux/mman.h>
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#include <asm/tlb.h>
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#include <asm/pgalloc.h>
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#include "internal.h"
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/*
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* By default transparent hugepage support is enabled for all mappings
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* and khugepaged scans all mappings. Defrag is only invoked by
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* khugepaged hugepage allocations and by page faults inside
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* MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
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* allocations.
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*/
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unsigned long transparent_hugepage_flags __read_mostly =
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
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(1<<TRANSPARENT_HUGEPAGE_FLAG)|
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#endif
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
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(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
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#endif
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
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/* default scan 8*512 pte (or vmas) every 30 second */
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static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
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static unsigned int khugepaged_pages_collapsed;
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static unsigned int khugepaged_full_scans;
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static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
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/* during fragmentation poll the hugepage allocator once every minute */
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static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
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static struct task_struct *khugepaged_thread __read_mostly;
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static DEFINE_MUTEX(khugepaged_mutex);
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static DEFINE_SPINLOCK(khugepaged_mm_lock);
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static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
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/*
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* default collapse hugepages if there is at least one pte mapped like
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* it would have happened if the vma was large enough during page
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* fault.
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*/
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static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
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static int khugepaged(void *none);
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static int mm_slots_hash_init(void);
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static int khugepaged_slab_init(void);
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static void khugepaged_slab_free(void);
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#define MM_SLOTS_HASH_HEADS 1024
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static struct hlist_head *mm_slots_hash __read_mostly;
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static struct kmem_cache *mm_slot_cache __read_mostly;
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/**
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* struct mm_slot - hash lookup from mm to mm_slot
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* @hash: hash collision list
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* @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
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* @mm: the mm that this information is valid for
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*/
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struct mm_slot {
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struct hlist_node hash;
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struct list_head mm_node;
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struct mm_struct *mm;
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};
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/**
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* struct khugepaged_scan - cursor for scanning
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* @mm_head: the head of the mm list to scan
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* @mm_slot: the current mm_slot we are scanning
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* @address: the next address inside that to be scanned
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*
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* There is only the one khugepaged_scan instance of this cursor structure.
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*/
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struct khugepaged_scan {
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struct list_head mm_head;
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struct mm_slot *mm_slot;
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unsigned long address;
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};
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static struct khugepaged_scan khugepaged_scan = {
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.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
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};
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static int set_recommended_min_free_kbytes(void)
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{
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struct zone *zone;
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int nr_zones = 0;
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unsigned long recommended_min;
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extern int min_free_kbytes;
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if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,
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&transparent_hugepage_flags) &&
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!test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
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&transparent_hugepage_flags))
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return 0;
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for_each_populated_zone(zone)
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nr_zones++;
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/* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
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recommended_min = pageblock_nr_pages * nr_zones * 2;
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/*
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* Make sure that on average at least two pageblocks are almost free
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* of another type, one for a migratetype to fall back to and a
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* second to avoid subsequent fallbacks of other types There are 3
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* MIGRATE_TYPES we care about.
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*/
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recommended_min += pageblock_nr_pages * nr_zones *
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MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
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/* don't ever allow to reserve more than 5% of the lowmem */
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recommended_min = min(recommended_min,
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(unsigned long) nr_free_buffer_pages() / 20);
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recommended_min <<= (PAGE_SHIFT-10);
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if (recommended_min > min_free_kbytes)
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min_free_kbytes = recommended_min;
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setup_per_zone_wmarks();
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return 0;
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}
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late_initcall(set_recommended_min_free_kbytes);
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static int start_khugepaged(void)
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{
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int err = 0;
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if (khugepaged_enabled()) {
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int wakeup;
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if (unlikely(!mm_slot_cache || !mm_slots_hash)) {
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err = -ENOMEM;
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goto out;
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}
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mutex_lock(&khugepaged_mutex);
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if (!khugepaged_thread)
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khugepaged_thread = kthread_run(khugepaged, NULL,
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"khugepaged");
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if (unlikely(IS_ERR(khugepaged_thread))) {
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printk(KERN_ERR
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"khugepaged: kthread_run(khugepaged) failed\n");
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err = PTR_ERR(khugepaged_thread);
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khugepaged_thread = NULL;
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}
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wakeup = !list_empty(&khugepaged_scan.mm_head);
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mutex_unlock(&khugepaged_mutex);
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if (wakeup)
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wake_up_interruptible(&khugepaged_wait);
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set_recommended_min_free_kbytes();
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} else
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/* wakeup to exit */
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wake_up_interruptible(&khugepaged_wait);
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out:
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return err;
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}
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#ifdef CONFIG_SYSFS
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static ssize_t double_flag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf,
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enum transparent_hugepage_flag enabled,
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enum transparent_hugepage_flag req_madv)
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{
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if (test_bit(enabled, &transparent_hugepage_flags)) {
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VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
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return sprintf(buf, "[always] madvise never\n");
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} else if (test_bit(req_madv, &transparent_hugepage_flags))
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return sprintf(buf, "always [madvise] never\n");
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else
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return sprintf(buf, "always madvise [never]\n");
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}
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static ssize_t double_flag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count,
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enum transparent_hugepage_flag enabled,
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enum transparent_hugepage_flag req_madv)
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{
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if (!memcmp("always", buf,
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min(sizeof("always")-1, count))) {
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set_bit(enabled, &transparent_hugepage_flags);
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clear_bit(req_madv, &transparent_hugepage_flags);
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} else if (!memcmp("madvise", buf,
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min(sizeof("madvise")-1, count))) {
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clear_bit(enabled, &transparent_hugepage_flags);
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set_bit(req_madv, &transparent_hugepage_flags);
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} else if (!memcmp("never", buf,
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min(sizeof("never")-1, count))) {
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clear_bit(enabled, &transparent_hugepage_flags);
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clear_bit(req_madv, &transparent_hugepage_flags);
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} else
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return -EINVAL;
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return count;
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}
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static ssize_t enabled_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return double_flag_show(kobj, attr, buf,
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TRANSPARENT_HUGEPAGE_FLAG,
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TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
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}
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static ssize_t enabled_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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ssize_t ret;
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ret = double_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_FLAG,
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TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
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if (ret > 0) {
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int err = start_khugepaged();
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if (err)
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ret = err;
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}
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if (ret > 0 &&
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(test_bit(TRANSPARENT_HUGEPAGE_FLAG,
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&transparent_hugepage_flags) ||
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test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
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&transparent_hugepage_flags)))
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set_recommended_min_free_kbytes();
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return ret;
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}
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static struct kobj_attribute enabled_attr =
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__ATTR(enabled, 0644, enabled_show, enabled_store);
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static ssize_t single_flag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf,
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enum transparent_hugepage_flag flag)
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{
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return sprintf(buf, "%d\n",
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!!test_bit(flag, &transparent_hugepage_flags));
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}
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static ssize_t single_flag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count,
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enum transparent_hugepage_flag flag)
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{
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unsigned long value;
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int ret;
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ret = kstrtoul(buf, 10, &value);
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if (ret < 0)
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return ret;
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if (value > 1)
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return -EINVAL;
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if (value)
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set_bit(flag, &transparent_hugepage_flags);
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else
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clear_bit(flag, &transparent_hugepage_flags);
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return count;
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}
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/*
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* Currently defrag only disables __GFP_NOWAIT for allocation. A blind
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* __GFP_REPEAT is too aggressive, it's never worth swapping tons of
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* memory just to allocate one more hugepage.
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*/
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static ssize_t defrag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return double_flag_show(kobj, attr, buf,
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TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
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TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
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}
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static ssize_t defrag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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return double_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
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TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
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}
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static struct kobj_attribute defrag_attr =
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__ATTR(defrag, 0644, defrag_show, defrag_store);
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#ifdef CONFIG_DEBUG_VM
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static ssize_t debug_cow_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return single_flag_show(kobj, attr, buf,
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TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
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}
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static ssize_t debug_cow_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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return single_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
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}
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static struct kobj_attribute debug_cow_attr =
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__ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
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#endif /* CONFIG_DEBUG_VM */
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static struct attribute *hugepage_attr[] = {
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&enabled_attr.attr,
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&defrag_attr.attr,
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#ifdef CONFIG_DEBUG_VM
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&debug_cow_attr.attr,
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#endif
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NULL,
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};
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static struct attribute_group hugepage_attr_group = {
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.attrs = hugepage_attr,
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};
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static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
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}
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static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned long msecs;
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int err;
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err = strict_strtoul(buf, 10, &msecs);
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if (err || msecs > UINT_MAX)
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return -EINVAL;
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khugepaged_scan_sleep_millisecs = msecs;
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wake_up_interruptible(&khugepaged_wait);
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return count;
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}
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static struct kobj_attribute scan_sleep_millisecs_attr =
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__ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
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scan_sleep_millisecs_store);
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static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
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}
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static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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unsigned long msecs;
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int err;
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err = strict_strtoul(buf, 10, &msecs);
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if (err || msecs > UINT_MAX)
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return -EINVAL;
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khugepaged_alloc_sleep_millisecs = msecs;
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wake_up_interruptible(&khugepaged_wait);
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return count;
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}
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static struct kobj_attribute alloc_sleep_millisecs_attr =
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__ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
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alloc_sleep_millisecs_store);
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static ssize_t pages_to_scan_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
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}
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static ssize_t pages_to_scan_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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int err;
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unsigned long pages;
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err = strict_strtoul(buf, 10, &pages);
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if (err || !pages || pages > UINT_MAX)
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return -EINVAL;
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khugepaged_pages_to_scan = pages;
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return count;
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}
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static struct kobj_attribute pages_to_scan_attr =
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__ATTR(pages_to_scan, 0644, pages_to_scan_show,
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pages_to_scan_store);
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static ssize_t pages_collapsed_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
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}
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static struct kobj_attribute pages_collapsed_attr =
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__ATTR_RO(pages_collapsed);
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|
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static ssize_t full_scans_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_full_scans);
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}
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static struct kobj_attribute full_scans_attr =
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__ATTR_RO(full_scans);
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|
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static ssize_t khugepaged_defrag_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return single_flag_show(kobj, attr, buf,
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TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
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}
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static ssize_t khugepaged_defrag_store(struct kobject *kobj,
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struct kobj_attribute *attr,
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const char *buf, size_t count)
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{
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return single_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
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}
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static struct kobj_attribute khugepaged_defrag_attr =
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__ATTR(defrag, 0644, khugepaged_defrag_show,
|
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khugepaged_defrag_store);
|
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|
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/*
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* max_ptes_none controls if khugepaged should collapse hugepages over
|
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* any unmapped ptes in turn potentially increasing the memory
|
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* footprint of the vmas. When max_ptes_none is 0 khugepaged will not
|
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* reduce the available free memory in the system as it
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* runs. Increasing max_ptes_none will instead potentially reduce the
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* free memory in the system during the khugepaged scan.
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*/
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static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
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struct kobj_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
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}
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static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
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struct kobj_attribute *attr,
|
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const char *buf, size_t count)
|
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{
|
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int err;
|
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unsigned long max_ptes_none;
|
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|
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err = strict_strtoul(buf, 10, &max_ptes_none);
|
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if (err || max_ptes_none > HPAGE_PMD_NR-1)
|
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return -EINVAL;
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|
|
|
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)) {
|
|
printk(KERN_ERR "hugepage: failed kobject create\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
|
|
if (err) {
|
|
printk(KERN_ERR "hugepage: failed register hugeage group\n");
|
|
goto delete_obj;
|
|
}
|
|
|
|
err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
|
|
if (err) {
|
|
printk(KERN_ERR "hugepage: failed register hugeage 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;
|
|
|
|
err = mm_slots_hash_init();
|
|
if (err) {
|
|
khugepaged_slab_free();
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* 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();
|
|
|
|
set_recommended_min_free_kbytes();
|
|
|
|
return 0;
|
|
out:
|
|
hugepage_exit_sysfs(hugepage_kobj);
|
|
return err;
|
|
}
|
|
module_init(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)
|
|
printk(KERN_WARNING
|
|
"transparent_hugepage= cannot parse, ignored\n");
|
|
return ret;
|
|
}
|
|
__setup("transparent_hugepage=", setup_transparent_hugepage);
|
|
|
|
static void prepare_pmd_huge_pte(pgtable_t pgtable,
|
|
struct mm_struct *mm)
|
|
{
|
|
assert_spin_locked(&mm->page_table_lock);
|
|
|
|
/* FIFO */
|
|
if (!mm->pmd_huge_pte)
|
|
INIT_LIST_HEAD(&pgtable->lru);
|
|
else
|
|
list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
|
|
mm->pmd_huge_pte = pgtable;
|
|
}
|
|
|
|
static inline 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 int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long haddr, pmd_t *pmd,
|
|
struct page *page)
|
|
{
|
|
int ret = 0;
|
|
pgtable_t pgtable;
|
|
|
|
VM_BUG_ON(!PageCompound(page));
|
|
pgtable = pte_alloc_one(mm, haddr);
|
|
if (unlikely(!pgtable)) {
|
|
mem_cgroup_uncharge_page(page);
|
|
put_page(page);
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
clear_huge_page(page, haddr, HPAGE_PMD_NR);
|
|
__SetPageUptodate(page);
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (unlikely(!pmd_none(*pmd))) {
|
|
spin_unlock(&mm->page_table_lock);
|
|
mem_cgroup_uncharge_page(page);
|
|
put_page(page);
|
|
pte_free(mm, pgtable);
|
|
} else {
|
|
pmd_t entry;
|
|
entry = mk_pmd(page, vma->vm_page_prot);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
entry = pmd_mkhuge(entry);
|
|
/*
|
|
* The spinlocking to take the lru_lock inside
|
|
* page_add_new_anon_rmap() acts as a full memory
|
|
* barrier to be sure clear_huge_page writes become
|
|
* visible after the set_pmd_at() write.
|
|
*/
|
|
page_add_new_anon_rmap(page, vma, haddr);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
prepare_pmd_huge_pte(pgtable, mm);
|
|
add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
spin_unlock(&mm->page_table_lock);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
#ifndef CONFIG_NUMA
|
|
static inline struct page *alloc_hugepage(int defrag)
|
|
{
|
|
return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
|
|
HPAGE_PMD_ORDER);
|
|
}
|
|
#endif
|
|
|
|
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;
|
|
pte_t *pte;
|
|
|
|
if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return VM_FAULT_OOM;
|
|
if (unlikely(khugepaged_enter(vma)))
|
|
return VM_FAULT_OOM;
|
|
page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
|
|
vma, haddr, numa_node_id(), 0);
|
|
if (unlikely(!page)) {
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
goto out;
|
|
}
|
|
count_vm_event(THP_FAULT_ALLOC);
|
|
if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
|
|
put_page(page);
|
|
goto out;
|
|
}
|
|
|
|
return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
|
|
}
|
|
out:
|
|
/*
|
|
* Use __pte_alloc instead of pte_alloc_map, because we can't
|
|
* run pte_offset_map on the pmd, if an huge pmd could
|
|
* materialize from under us from a different thread.
|
|
*/
|
|
if (unlikely(__pte_alloc(mm, vma, pmd, address)))
|
|
return VM_FAULT_OOM;
|
|
/* if an huge pmd materialized from under us just retry later */
|
|
if (unlikely(pmd_trans_huge(*pmd)))
|
|
return 0;
|
|
/*
|
|
* A regular pmd is established and it can't morph into a huge pmd
|
|
* from under us anymore at this point because we hold the mmap_sem
|
|
* read mode and khugepaged takes it in write mode. So now it's
|
|
* safe to run pte_offset_map().
|
|
*/
|
|
pte = pte_offset_map(pmd, address);
|
|
return handle_pte_fault(mm, vma, address, pte, pmd, flags);
|
|
}
|
|
|
|
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)
|
|
{
|
|
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;
|
|
|
|
spin_lock(&dst_mm->page_table_lock);
|
|
spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
|
|
|
|
ret = -EAGAIN;
|
|
pmd = *src_pmd;
|
|
if (unlikely(!pmd_trans_huge(pmd))) {
|
|
pte_free(dst_mm, pgtable);
|
|
goto out_unlock;
|
|
}
|
|
if (unlikely(pmd_trans_splitting(pmd))) {
|
|
/* split huge page running from under us */
|
|
spin_unlock(&src_mm->page_table_lock);
|
|
spin_unlock(&dst_mm->page_table_lock);
|
|
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(!PageHead(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));
|
|
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
|
|
prepare_pmd_huge_pte(pgtable, dst_mm);
|
|
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock(&src_mm->page_table_lock);
|
|
spin_unlock(&dst_mm->page_table_lock);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/* no "address" argument so destroys page coloring of some arch */
|
|
pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
|
|
{
|
|
pgtable_t pgtable;
|
|
|
|
assert_spin_locked(&mm->page_table_lock);
|
|
|
|
/* FIFO */
|
|
pgtable = mm->pmd_huge_pte;
|
|
if (list_empty(&pgtable->lru))
|
|
mm->pmd_huge_pte = NULL;
|
|
else {
|
|
mm->pmd_huge_pte = list_entry(pgtable->lru.next,
|
|
struct page, lru);
|
|
list_del(&pgtable->lru);
|
|
}
|
|
return pgtable;
|
|
}
|
|
|
|
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)
|
|
{
|
|
pgtable_t pgtable;
|
|
pmd_t _pmd;
|
|
int ret = 0, i;
|
|
struct page **pages;
|
|
|
|
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_newpage_charge(pages[i], mm,
|
|
GFP_KERNEL))) {
|
|
if (pages[i])
|
|
put_page(pages[i]);
|
|
mem_cgroup_uncharge_start();
|
|
while (--i >= 0) {
|
|
mem_cgroup_uncharge_page(pages[i]);
|
|
put_page(pages[i]);
|
|
}
|
|
mem_cgroup_uncharge_end();
|
|
kfree(pages);
|
|
ret |= VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
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();
|
|
}
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd)))
|
|
goto out_free_pages;
|
|
VM_BUG_ON(!PageHead(page));
|
|
|
|
pmdp_clear_flush_notify(vma, haddr, pmd);
|
|
/* leave pmd empty until pte is filled */
|
|
|
|
pgtable = get_pmd_huge_pte(mm);
|
|
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);
|
|
page_add_new_anon_rmap(pages[i], vma, haddr);
|
|
pte = pte_offset_map(&_pmd, haddr);
|
|
VM_BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, haddr, pte, entry);
|
|
pte_unmap(pte);
|
|
}
|
|
kfree(pages);
|
|
|
|
mm->nr_ptes++;
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
pmd_populate(mm, pmd, pgtable);
|
|
page_remove_rmap(page);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
ret |= VM_FAULT_WRITE;
|
|
put_page(page);
|
|
|
|
out:
|
|
return ret;
|
|
|
|
out_free_pages:
|
|
spin_unlock(&mm->page_table_lock);
|
|
mem_cgroup_uncharge_start();
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
mem_cgroup_uncharge_page(pages[i]);
|
|
put_page(pages[i]);
|
|
}
|
|
mem_cgroup_uncharge_end();
|
|
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)
|
|
{
|
|
int ret = 0;
|
|
struct page *page, *new_page;
|
|
unsigned long haddr;
|
|
|
|
VM_BUG_ON(!vma->anon_vma);
|
|
spin_lock(&mm->page_table_lock);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd)))
|
|
goto out_unlock;
|
|
|
|
page = pmd_page(orig_pmd);
|
|
VM_BUG_ON(!PageCompound(page) || !PageHead(page));
|
|
haddr = address & HPAGE_PMD_MASK;
|
|
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(vma, address, entry);
|
|
ret |= VM_FAULT_WRITE;
|
|
goto out_unlock;
|
|
}
|
|
get_page(page);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
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)) {
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
|
|
pmd, orig_pmd, page, haddr);
|
|
put_page(page);
|
|
goto out;
|
|
}
|
|
count_vm_event(THP_FAULT_ALLOC);
|
|
|
|
if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
|
|
put_page(new_page);
|
|
put_page(page);
|
|
ret |= VM_FAULT_OOM;
|
|
goto out;
|
|
}
|
|
|
|
copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
|
|
__SetPageUptodate(new_page);
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
put_page(page);
|
|
if (unlikely(!pmd_same(*pmd, orig_pmd))) {
|
|
mem_cgroup_uncharge_page(new_page);
|
|
put_page(new_page);
|
|
} else {
|
|
pmd_t entry;
|
|
VM_BUG_ON(!PageHead(page));
|
|
entry = mk_pmd(new_page, vma->vm_page_prot);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
entry = pmd_mkhuge(entry);
|
|
pmdp_clear_flush_notify(vma, haddr, pmd);
|
|
page_add_new_anon_rmap(new_page, vma, haddr);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
update_mmu_cache(vma, address, entry);
|
|
page_remove_rmap(page);
|
|
put_page(page);
|
|
ret |= VM_FAULT_WRITE;
|
|
}
|
|
out_unlock:
|
|
spin_unlock(&mm->page_table_lock);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
struct page *follow_trans_huge_pmd(struct mm_struct *mm,
|
|
unsigned long addr,
|
|
pmd_t *pmd,
|
|
unsigned int flags)
|
|
{
|
|
struct page *page = NULL;
|
|
|
|
assert_spin_locked(&mm->page_table_lock);
|
|
|
|
if (flags & FOLL_WRITE && !pmd_write(*pmd))
|
|
goto out;
|
|
|
|
page = pmd_page(*pmd);
|
|
VM_BUG_ON(!PageHead(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));
|
|
set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
|
|
}
|
|
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
|
|
VM_BUG_ON(!PageCompound(page));
|
|
if (flags & FOLL_GET)
|
|
get_page_foll(page);
|
|
|
|
out:
|
|
return page;
|
|
}
|
|
|
|
int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pmd_t *pmd, unsigned long addr)
|
|
{
|
|
int ret = 0;
|
|
|
|
spin_lock(&tlb->mm->page_table_lock);
|
|
if (likely(pmd_trans_huge(*pmd))) {
|
|
if (unlikely(pmd_trans_splitting(*pmd))) {
|
|
spin_unlock(&tlb->mm->page_table_lock);
|
|
wait_split_huge_page(vma->anon_vma,
|
|
pmd);
|
|
} else {
|
|
struct page *page;
|
|
pgtable_t pgtable;
|
|
pgtable = get_pmd_huge_pte(tlb->mm);
|
|
page = pmd_page(*pmd);
|
|
pmd_clear(pmd);
|
|
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
|
|
page_remove_rmap(page);
|
|
VM_BUG_ON(page_mapcount(page) < 0);
|
|
add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
|
|
VM_BUG_ON(!PageHead(page));
|
|
spin_unlock(&tlb->mm->page_table_lock);
|
|
tlb_remove_page(tlb, page);
|
|
pte_free(tlb->mm, pgtable);
|
|
ret = 1;
|
|
}
|
|
} else
|
|
spin_unlock(&tlb->mm->page_table_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end,
|
|
unsigned char *vec)
|
|
{
|
|
int ret = 0;
|
|
|
|
spin_lock(&vma->vm_mm->page_table_lock);
|
|
if (likely(pmd_trans_huge(*pmd))) {
|
|
ret = !pmd_trans_splitting(*pmd);
|
|
spin_unlock(&vma->vm_mm->page_table_lock);
|
|
if (unlikely(!ret))
|
|
wait_split_huge_page(vma->anon_vma, pmd);
|
|
else {
|
|
/*
|
|
* All logical pages in the range are present
|
|
* if backed by a huge page.
|
|
*/
|
|
memset(vec, 1, (end - addr) >> PAGE_SHIFT);
|
|
}
|
|
} else
|
|
spin_unlock(&vma->vm_mm->page_table_lock);
|
|
|
|
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)
|
|
{
|
|
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;
|
|
}
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (likely(pmd_trans_huge(*old_pmd))) {
|
|
if (pmd_trans_splitting(*old_pmd)) {
|
|
spin_unlock(&mm->page_table_lock);
|
|
wait_split_huge_page(vma->anon_vma, old_pmd);
|
|
ret = -1;
|
|
} else {
|
|
pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
|
|
VM_BUG_ON(!pmd_none(*new_pmd));
|
|
set_pmd_at(mm, new_addr, new_pmd, pmd);
|
|
spin_unlock(&mm->page_table_lock);
|
|
ret = 1;
|
|
}
|
|
} else {
|
|
spin_unlock(&mm->page_table_lock);
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, pgprot_t newprot)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
int ret = 0;
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (likely(pmd_trans_huge(*pmd))) {
|
|
if (unlikely(pmd_trans_splitting(*pmd))) {
|
|
spin_unlock(&mm->page_table_lock);
|
|
wait_split_huge_page(vma->anon_vma, pmd);
|
|
} else {
|
|
pmd_t entry;
|
|
|
|
entry = pmdp_get_and_clear(mm, addr, pmd);
|
|
entry = pmd_modify(entry, newprot);
|
|
set_pmd_at(mm, addr, pmd, entry);
|
|
spin_unlock(&vma->vm_mm->page_table_lock);
|
|
ret = 1;
|
|
}
|
|
} else
|
|
spin_unlock(&vma->vm_mm->page_table_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
pmd_t *page_check_address_pmd(struct page *page,
|
|
struct mm_struct *mm,
|
|
unsigned long address,
|
|
enum page_check_address_pmd_flag flag)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd, *ret = NULL;
|
|
|
|
if (address & ~HPAGE_PMD_MASK)
|
|
goto out;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
pud = pud_offset(pgd, address);
|
|
if (!pud_present(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
if (pmd_none(*pmd))
|
|
goto out;
|
|
if (pmd_page(*pmd) != page)
|
|
goto out;
|
|
/*
|
|
* 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 out;
|
|
if (pmd_trans_huge(*pmd)) {
|
|
VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
|
|
!pmd_trans_splitting(*pmd));
|
|
ret = pmd;
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static int __split_huge_page_splitting(struct page *page,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pmd_t *pmd;
|
|
int ret = 0;
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
pmd = page_check_address_pmd(page, mm, address,
|
|
PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
|
|
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->mutex to
|
|
* serialize against split_huge_page*.
|
|
*/
|
|
pmdp_splitting_flush_notify(vma, address, pmd);
|
|
ret = 1;
|
|
}
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void __split_huge_page_refcount(struct page *page)
|
|
{
|
|
int i;
|
|
struct zone *zone = page_zone(page);
|
|
int tail_count = 0;
|
|
|
|
/* prevent PageLRU to go away from under us, and freeze lru stats */
|
|
spin_lock_irq(&zone->lru_lock);
|
|
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();
|
|
|
|
/*
|
|
* 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)));
|
|
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;
|
|
|
|
BUG_ON(!PageAnon(page_tail));
|
|
BUG_ON(!PageUptodate(page_tail));
|
|
BUG_ON(!PageDirty(page_tail));
|
|
BUG_ON(!PageSwapBacked(page_tail));
|
|
|
|
|
|
lru_add_page_tail(zone, page, page_tail);
|
|
}
|
|
atomic_sub(tail_count, &page->_count);
|
|
BUG_ON(atomic_read(&page->_count) <= 0);
|
|
|
|
__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
|
|
__mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
|
|
|
|
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;
|
|
pmd_t *pmd, _pmd;
|
|
int ret = 0, i;
|
|
pgtable_t pgtable;
|
|
unsigned long haddr;
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
pmd = page_check_address_pmd(page, mm, address,
|
|
PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
|
|
if (pmd) {
|
|
pgtable = get_pmd_huge_pte(mm);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0, haddr = address; i < HPAGE_PMD_NR;
|
|
i++, haddr += PAGE_SIZE) {
|
|
pte_t *pte, entry;
|
|
BUG_ON(PageCompound(page+i));
|
|
entry = mk_pte(page + i, vma->vm_page_prot);
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
if (!pmd_write(*pmd))
|
|
entry = pte_wrprotect(entry);
|
|
else
|
|
BUG_ON(page_mapcount(page) != 1);
|
|
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);
|
|
}
|
|
|
|
mm->nr_ptes++;
|
|
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.
|
|
*/
|
|
set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
|
|
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
|
|
pmd_populate(mm, pmd, pgtable);
|
|
ret = 1;
|
|
}
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* must be called with anon_vma->root->mutex hold */
|
|
static void __split_huge_page(struct page *page,
|
|
struct anon_vma *anon_vma)
|
|
{
|
|
int mapcount, mapcount2;
|
|
struct anon_vma_chain *avc;
|
|
|
|
BUG_ON(!PageHead(page));
|
|
BUG_ON(PageTail(page));
|
|
|
|
mapcount = 0;
|
|
list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
|
|
struct vm_area_struct *vma = avc->vma;
|
|
unsigned long addr = vma_address(page, vma);
|
|
BUG_ON(is_vma_temporary_stack(vma));
|
|
if (addr == -EFAULT)
|
|
continue;
|
|
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))
|
|
printk(KERN_ERR "mapcount %d page_mapcount %d\n",
|
|
mapcount, page_mapcount(page));
|
|
BUG_ON(mapcount != page_mapcount(page));
|
|
|
|
__split_huge_page_refcount(page);
|
|
|
|
mapcount2 = 0;
|
|
list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
|
|
struct vm_area_struct *vma = avc->vma;
|
|
unsigned long addr = vma_address(page, vma);
|
|
BUG_ON(is_vma_temporary_stack(vma));
|
|
if (addr == -EFAULT)
|
|
continue;
|
|
mapcount2 += __split_huge_page_map(page, vma, addr);
|
|
}
|
|
if (mapcount != mapcount2)
|
|
printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
|
|
mapcount, mapcount2, page_mapcount(page));
|
|
BUG_ON(mapcount != mapcount2);
|
|
}
|
|
|
|
int split_huge_page(struct page *page)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
int ret = 1;
|
|
|
|
BUG_ON(!PageAnon(page));
|
|
anon_vma = page_lock_anon_vma(page);
|
|
if (!anon_vma)
|
|
goto out;
|
|
ret = 0;
|
|
if (!PageCompound(page))
|
|
goto out_unlock;
|
|
|
|
BUG_ON(!PageSwapBacked(page));
|
|
__split_huge_page(page, anon_vma);
|
|
count_vm_event(THP_SPLIT);
|
|
|
|
BUG_ON(PageCompound(page));
|
|
out_unlock:
|
|
page_unlock_anon_vma(anon_vma);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
|
|
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:
|
|
/*
|
|
* 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)))
|
|
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_free(void)
|
|
{
|
|
kmem_cache_destroy(mm_slot_cache);
|
|
mm_slot_cache = NULL;
|
|
}
|
|
|
|
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 int __init mm_slots_hash_init(void)
|
|
{
|
|
mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
|
|
GFP_KERNEL);
|
|
if (!mm_slots_hash)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
#if 0
|
|
static void __init mm_slots_hash_free(void)
|
|
{
|
|
kfree(mm_slots_hash);
|
|
mm_slots_hash = NULL;
|
|
}
|
|
#endif
|
|
|
|
static struct mm_slot *get_mm_slot(struct mm_struct *mm)
|
|
{
|
|
struct mm_slot *mm_slot;
|
|
struct hlist_head *bucket;
|
|
struct hlist_node *node;
|
|
|
|
bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
|
|
% MM_SLOTS_HASH_HEADS];
|
|
hlist_for_each_entry(mm_slot, node, bucket, hash) {
|
|
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)
|
|
{
|
|
struct hlist_head *bucket;
|
|
|
|
bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
|
|
% MM_SLOTS_HASH_HEADS];
|
|
mm_slot->mm = mm;
|
|
hlist_add_head(&mm_slot->hash, bucket);
|
|
}
|
|
|
|
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(khugepaged_test_exit(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 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;
|
|
/*
|
|
* If is_pfn_mapping() is true is_learn_pfn_mapping() must be
|
|
* true too, verify it here.
|
|
*/
|
|
VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
|
|
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
|
|
hend = vma->vm_end & HPAGE_PMD_MASK;
|
|
if (hstart < hend)
|
|
return khugepaged_enter(vma);
|
|
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) {
|
|
hlist_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 void release_all_pte_pages(pte_t *pte)
|
|
{
|
|
release_pte_pages(pte, pte + HPAGE_PMD_NR);
|
|
}
|
|
|
|
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, isolated = 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 {
|
|
release_pte_pages(pte, _pte);
|
|
goto out;
|
|
}
|
|
}
|
|
if (!pte_present(pteval) || !pte_write(pteval)) {
|
|
release_pte_pages(pte, _pte);
|
|
goto out;
|
|
}
|
|
page = vm_normal_page(vma, address, pteval);
|
|
if (unlikely(!page)) {
|
|
release_pte_pages(pte, _pte);
|
|
goto out;
|
|
}
|
|
VM_BUG_ON(PageCompound(page));
|
|
BUG_ON(!PageAnon(page));
|
|
VM_BUG_ON(!PageSwapBacked(page));
|
|
|
|
/* cannot use mapcount: can't collapse if there's a gup pin */
|
|
if (page_count(page) != 1) {
|
|
release_pte_pages(pte, _pte);
|
|
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)) {
|
|
release_pte_pages(pte, _pte);
|
|
goto out;
|
|
}
|
|
/*
|
|
* Isolate the page to avoid collapsing an hugepage
|
|
* currently in use by the VM.
|
|
*/
|
|
if (isolate_lru_page(page)) {
|
|
unlock_page(page);
|
|
release_pte_pages(pte, _pte);
|
|
goto out;
|
|
}
|
|
/* 0 stands for page_is_file_cache(page) == false */
|
|
inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
|
|
VM_BUG_ON(!PageLocked(page));
|
|
VM_BUG_ON(PageLRU(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 (unlikely(!referenced))
|
|
release_all_pte_pages(pte);
|
|
else
|
|
isolated = 1;
|
|
out:
|
|
return isolated;
|
|
}
|
|
|
|
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_mapcount(src_page) != 1);
|
|
VM_BUG_ON(page_count(src_page) != 2);
|
|
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 collapse_huge_page(struct mm_struct *mm,
|
|
unsigned long address,
|
|
struct page **hpage,
|
|
struct vm_area_struct *vma,
|
|
int node)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd, _pmd;
|
|
pte_t *pte;
|
|
pgtable_t pgtable;
|
|
struct page *new_page;
|
|
spinlock_t *ptl;
|
|
int isolated;
|
|
unsigned long hstart, hend;
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
#ifndef CONFIG_NUMA
|
|
up_read(&mm->mmap_sem);
|
|
VM_BUG_ON(!*hpage);
|
|
new_page = *hpage;
|
|
#else
|
|
VM_BUG_ON(*hpage);
|
|
/*
|
|
* Allocate the page while the vma is still valid and under
|
|
* the mmap_sem read mode so there is no memory allocation
|
|
* later when we take the mmap_sem in write mode. This is more
|
|
* friendly behavior (OTOH it may actually hide bugs) to
|
|
* filesystems in userland with daemons allocating memory in
|
|
* the userland I/O paths. Allocating memory with the
|
|
* mmap_sem in read mode is good idea also to allow greater
|
|
* scalability.
|
|
*/
|
|
new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
|
|
node, __GFP_OTHER_NODE);
|
|
|
|
/*
|
|
* After allocating the hugepage, release the mmap_sem read lock in
|
|
* preparation for taking it in write mode.
|
|
*/
|
|
up_read(&mm->mmap_sem);
|
|
if (unlikely(!new_page)) {
|
|
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
|
|
*hpage = ERR_PTR(-ENOMEM);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
count_vm_event(THP_COLLAPSE_ALLOC);
|
|
if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
|
|
#ifdef CONFIG_NUMA
|
|
put_page(new_page);
|
|
#endif
|
|
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);
|
|
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 ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
|
|
(vma->vm_flags & VM_NOHUGEPAGE))
|
|
goto out;
|
|
|
|
if (!vma->anon_vma || vma->vm_ops)
|
|
goto out;
|
|
if (is_vma_temporary_stack(vma))
|
|
goto out;
|
|
/*
|
|
* If is_pfn_mapping() is true is_learn_pfn_mapping() must be
|
|
* true too, verify it here.
|
|
*/
|
|
VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
pud = pud_offset(pgd, address);
|
|
if (!pud_present(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
/* pmd can't go away or become huge under us */
|
|
if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
|
|
goto out;
|
|
|
|
anon_vma_lock(vma->anon_vma);
|
|
|
|
pte = pte_offset_map(pmd, address);
|
|
ptl = pte_lockptr(mm, pmd);
|
|
|
|
spin_lock(&mm->page_table_lock); /* 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_notify(vma, address, pmd);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
spin_lock(ptl);
|
|
isolated = __collapse_huge_page_isolate(vma, address, pte);
|
|
spin_unlock(ptl);
|
|
|
|
if (unlikely(!isolated)) {
|
|
pte_unmap(pte);
|
|
spin_lock(&mm->page_table_lock);
|
|
BUG_ON(!pmd_none(*pmd));
|
|
set_pmd_at(mm, address, pmd, _pmd);
|
|
spin_unlock(&mm->page_table_lock);
|
|
anon_vma_unlock(vma->anon_vma);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* All pages are isolated and locked so anon_vma rmap
|
|
* can't run anymore.
|
|
*/
|
|
anon_vma_unlock(vma->anon_vma);
|
|
|
|
__collapse_huge_page_copy(pte, new_page, vma, address, ptl);
|
|
pte_unmap(pte);
|
|
__SetPageUptodate(new_page);
|
|
pgtable = pmd_pgtable(_pmd);
|
|
VM_BUG_ON(page_count(pgtable) != 1);
|
|
VM_BUG_ON(page_mapcount(pgtable) != 0);
|
|
|
|
_pmd = mk_pmd(new_page, vma->vm_page_prot);
|
|
_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
|
|
_pmd = pmd_mkhuge(_pmd);
|
|
|
|
/*
|
|
* 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(&mm->page_table_lock);
|
|
BUG_ON(!pmd_none(*pmd));
|
|
page_add_new_anon_rmap(new_page, vma, address);
|
|
set_pmd_at(mm, address, pmd, _pmd);
|
|
update_mmu_cache(vma, address, _pmd);
|
|
prepare_pmd_huge_pte(pgtable, mm);
|
|
mm->nr_ptes--;
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
#ifndef CONFIG_NUMA
|
|
*hpage = NULL;
|
|
#endif
|
|
khugepaged_pages_collapsed++;
|
|
out_up_write:
|
|
up_write(&mm->mmap_sem);
|
|
return;
|
|
|
|
out:
|
|
mem_cgroup_uncharge_page(new_page);
|
|
#ifdef CONFIG_NUMA
|
|
put_page(new_page);
|
|
#endif
|
|
goto out_up_write;
|
|
}
|
|
|
|
static int khugepaged_scan_pmd(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
unsigned long address,
|
|
struct page **hpage)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
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 = -1;
|
|
|
|
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
pud = pud_offset(pgd, address);
|
|
if (!pud_present(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
|
|
goto out;
|
|
|
|
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;
|
|
/*
|
|
* Chose the node of the first page. This could
|
|
* be more sophisticated and look at more pages,
|
|
* but isn't for now.
|
|
*/
|
|
if (node == -1)
|
|
node = page_to_nid(page);
|
|
VM_BUG_ON(PageCompound(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)
|
|
/* 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 */
|
|
hlist_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 ((!(vma->vm_flags & VM_HUGEPAGE) &&
|
|
!khugepaged_always()) ||
|
|
(vma->vm_flags & VM_NOHUGEPAGE)) {
|
|
skip:
|
|
progress++;
|
|
continue;
|
|
}
|
|
if (!vma->anon_vma || vma->vm_ops)
|
|
goto skip;
|
|
if (is_vma_temporary_stack(vma))
|
|
goto skip;
|
|
/*
|
|
* If is_pfn_mapping() is true is_learn_pfn_mapping()
|
|
* must be true too, verify it here.
|
|
*/
|
|
VM_BUG_ON(is_linear_pfn_mapping(vma) ||
|
|
vma->vm_flags & VM_NO_THP);
|
|
|
|
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) ||
|
|
!khugepaged_enabled();
|
|
}
|
|
|
|
static void khugepaged_do_scan(struct page **hpage)
|
|
{
|
|
unsigned int progress = 0, pass_through_head = 0;
|
|
unsigned int pages = khugepaged_pages_to_scan;
|
|
|
|
barrier(); /* write khugepaged_pages_to_scan to local stack */
|
|
|
|
while (progress < pages) {
|
|
cond_resched();
|
|
|
|
#ifndef CONFIG_NUMA
|
|
if (!*hpage) {
|
|
*hpage = alloc_hugepage(khugepaged_defrag());
|
|
if (unlikely(!*hpage)) {
|
|
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
|
|
break;
|
|
}
|
|
count_vm_event(THP_COLLAPSE_ALLOC);
|
|
}
|
|
#else
|
|
if (IS_ERR(*hpage))
|
|
break;
|
|
#endif
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
static void khugepaged_alloc_sleep(void)
|
|
{
|
|
wait_event_freezable_timeout(khugepaged_wait, false,
|
|
msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
|
|
}
|
|
|
|
#ifndef CONFIG_NUMA
|
|
static struct page *khugepaged_alloc_hugepage(void)
|
|
{
|
|
struct page *hpage;
|
|
|
|
do {
|
|
hpage = alloc_hugepage(khugepaged_defrag());
|
|
if (!hpage) {
|
|
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
|
|
khugepaged_alloc_sleep();
|
|
} else
|
|
count_vm_event(THP_COLLAPSE_ALLOC);
|
|
} while (unlikely(!hpage) &&
|
|
likely(khugepaged_enabled()));
|
|
return hpage;
|
|
}
|
|
#endif
|
|
|
|
static void khugepaged_loop(void)
|
|
{
|
|
struct page *hpage;
|
|
|
|
#ifdef CONFIG_NUMA
|
|
hpage = NULL;
|
|
#endif
|
|
while (likely(khugepaged_enabled())) {
|
|
#ifndef CONFIG_NUMA
|
|
hpage = khugepaged_alloc_hugepage();
|
|
if (unlikely(!hpage))
|
|
break;
|
|
#else
|
|
if (IS_ERR(hpage)) {
|
|
khugepaged_alloc_sleep();
|
|
hpage = NULL;
|
|
}
|
|
#endif
|
|
|
|
khugepaged_do_scan(&hpage);
|
|
#ifndef CONFIG_NUMA
|
|
if (hpage)
|
|
put_page(hpage);
|
|
#endif
|
|
try_to_freeze();
|
|
if (unlikely(kthread_should_stop()))
|
|
break;
|
|
if (khugepaged_has_work()) {
|
|
if (!khugepaged_scan_sleep_millisecs)
|
|
continue;
|
|
wait_event_freezable_timeout(khugepaged_wait, false,
|
|
msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
|
|
} else 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, 19);
|
|
|
|
/* serialize with start_khugepaged() */
|
|
mutex_lock(&khugepaged_mutex);
|
|
|
|
for (;;) {
|
|
mutex_unlock(&khugepaged_mutex);
|
|
VM_BUG_ON(khugepaged_thread != current);
|
|
khugepaged_loop();
|
|
VM_BUG_ON(khugepaged_thread != current);
|
|
|
|
mutex_lock(&khugepaged_mutex);
|
|
if (!khugepaged_enabled())
|
|
break;
|
|
if (unlikely(kthread_should_stop()))
|
|
break;
|
|
}
|
|
|
|
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);
|
|
|
|
khugepaged_thread = NULL;
|
|
mutex_unlock(&khugepaged_mutex);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
|
|
{
|
|
struct page *page;
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (unlikely(!pmd_trans_huge(*pmd))) {
|
|
spin_unlock(&mm->page_table_lock);
|
|
return;
|
|
}
|
|
page = pmd_page(*pmd);
|
|
VM_BUG_ON(!page_count(page));
|
|
get_page(page);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
split_huge_page(page);
|
|
|
|
put_page(page);
|
|
BUG_ON(pmd_trans_huge(*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, 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);
|
|
}
|
|
}
|