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![Yang Shi](/assets/img/avatar_default.png)
When debugging the bug reported by Wang Yugui [1], try_to_unmap() may fail, but the first VM_BUG_ON_PAGE() just checks page_mapcount() however it may miss the failure when head page is unmapped but other subpage is mapped. Then the second DEBUG_VM BUG() that check total mapcount would catch it. This may incur some confusion. As this is not a fatal issue, so consolidate the two DEBUG_VM checks into one VM_WARN_ON_ONCE_PAGE(). [1] https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/ Link: https://lkml.kernel.org/r/d0f0db68-98b8-ebfb-16dc-f29df24cf012@google.com Signed-off-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3256 lines
87 KiB
C
3256 lines
87 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2009 Red Hat, Inc.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/coredump.h>
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#include <linux/sched/numa_balancing.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/shrinker.h>
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#include <linux/mm_inline.h>
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#include <linux/swapops.h>
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#include <linux/dax.h>
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#include <linux/khugepaged.h>
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#include <linux/freezer.h>
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#include <linux/pfn_t.h>
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#include <linux/mman.h>
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#include <linux/memremap.h>
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#include <linux/pagemap.h>
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#include <linux/debugfs.h>
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#include <linux/migrate.h>
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#include <linux/hashtable.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/page_idle.h>
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#include <linux/shmem_fs.h>
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#include <linux/oom.h>
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#include <linux/numa.h>
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#include <linux/page_owner.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 disabled in order to avoid
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* risking an increased memory footprint for applications that are not
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* guaranteed to benefit from it. When transparent hugepage support is
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* enabled, it is for all mappings, and khugepaged scans all mappings.
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* Defrag is invoked by khugepaged hugepage allocations and by page faults
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* for all hugepage 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_REQ_MADV_FLAG)|
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(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
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(1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
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static struct shrinker deferred_split_shrinker;
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static atomic_t huge_zero_refcount;
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struct page *huge_zero_page __read_mostly;
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unsigned long huge_zero_pfn __read_mostly = ~0UL;
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bool transparent_hugepage_enabled(struct vm_area_struct *vma)
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{
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/* The addr is used to check if the vma size fits */
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unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
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if (!transhuge_vma_suitable(vma, addr))
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return false;
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if (vma_is_anonymous(vma))
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return __transparent_hugepage_enabled(vma);
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if (vma_is_shmem(vma))
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return shmem_huge_enabled(vma);
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return false;
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}
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static bool get_huge_zero_page(void)
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{
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struct page *zero_page;
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retry:
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if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
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return true;
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zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
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HPAGE_PMD_ORDER);
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if (!zero_page) {
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count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
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return false;
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}
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count_vm_event(THP_ZERO_PAGE_ALLOC);
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preempt_disable();
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if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
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preempt_enable();
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__free_pages(zero_page, compound_order(zero_page));
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goto retry;
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}
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WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
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/* We take additional reference here. It will be put back by shrinker */
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atomic_set(&huge_zero_refcount, 2);
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preempt_enable();
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return true;
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}
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static void put_huge_zero_page(void)
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{
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/*
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* Counter should never go to zero here. Only shrinker can put
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* last reference.
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*/
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BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
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}
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struct page *mm_get_huge_zero_page(struct mm_struct *mm)
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{
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if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
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return READ_ONCE(huge_zero_page);
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if (!get_huge_zero_page())
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return NULL;
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if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
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put_huge_zero_page();
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return READ_ONCE(huge_zero_page);
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}
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void mm_put_huge_zero_page(struct mm_struct *mm)
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{
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if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
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put_huge_zero_page();
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}
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static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
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struct shrink_control *sc)
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{
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/* we can free zero page only if last reference remains */
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return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
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}
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static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
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struct shrink_control *sc)
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{
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if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
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struct page *zero_page = xchg(&huge_zero_page, NULL);
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BUG_ON(zero_page == NULL);
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WRITE_ONCE(huge_zero_pfn, ~0UL);
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__free_pages(zero_page, compound_order(zero_page));
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return HPAGE_PMD_NR;
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}
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return 0;
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}
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static struct shrinker huge_zero_page_shrinker = {
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.count_objects = shrink_huge_zero_page_count,
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.scan_objects = shrink_huge_zero_page_scan,
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.seeks = DEFAULT_SEEKS,
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};
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#ifdef CONFIG_SYSFS
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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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const char *output;
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if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
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output = "[always] madvise never";
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else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
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&transparent_hugepage_flags))
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output = "always [madvise] never";
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else
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output = "always madvise [never]";
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return sysfs_emit(buf, "%s\n", output);
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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 = count;
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if (sysfs_streq(buf, "always")) {
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clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "madvise")) {
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clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "never")) {
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clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
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} else
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ret = -EINVAL;
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if (ret > 0) {
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int err = start_stop_khugepaged();
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if (err)
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ret = err;
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}
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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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ssize_t single_hugepage_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 sysfs_emit(buf, "%d\n",
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!!test_bit(flag, &transparent_hugepage_flags));
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}
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ssize_t single_hugepage_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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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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const char *output;
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if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
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&transparent_hugepage_flags))
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output = "[always] defer defer+madvise madvise never";
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else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
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&transparent_hugepage_flags))
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output = "always [defer] defer+madvise madvise never";
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else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
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&transparent_hugepage_flags))
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output = "always defer [defer+madvise] madvise never";
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else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
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&transparent_hugepage_flags))
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output = "always defer defer+madvise [madvise] never";
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else
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output = "always defer defer+madvise madvise [never]";
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return sysfs_emit(buf, "%s\n", output);
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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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if (sysfs_streq(buf, "always")) {
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "defer+madvise")) {
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "defer")) {
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "madvise")) {
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
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set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
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} else if (sysfs_streq(buf, "never")) {
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
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clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &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 struct kobj_attribute defrag_attr =
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__ATTR(defrag, 0644, defrag_show, defrag_store);
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static ssize_t use_zero_page_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return single_hugepage_flag_show(kobj, attr, buf,
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TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
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}
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static ssize_t use_zero_page_store(struct kobject *kobj,
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struct kobj_attribute *attr, const char *buf, size_t count)
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{
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return single_hugepage_flag_store(kobj, attr, buf, count,
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TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
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}
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static struct kobj_attribute use_zero_page_attr =
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__ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
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static ssize_t hpage_pmd_size_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
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}
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static struct kobj_attribute hpage_pmd_size_attr =
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__ATTR_RO(hpage_pmd_size);
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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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&use_zero_page_attr.attr,
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&hpage_pmd_size_attr.attr,
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#ifdef CONFIG_SHMEM
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&shmem_enabled_attr.attr,
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#endif
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NULL,
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};
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static const struct attribute_group hugepage_attr_group = {
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.attrs = hugepage_attr,
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};
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static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
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{
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int err;
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*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
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if (unlikely(!*hugepage_kobj)) {
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pr_err("failed to create transparent hugepage kobject\n");
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return -ENOMEM;
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}
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err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
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if (err) {
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pr_err("failed to register transparent hugepage group\n");
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goto delete_obj;
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}
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err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
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if (err) {
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pr_err("failed to register transparent hugepage group\n");
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goto remove_hp_group;
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}
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return 0;
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remove_hp_group:
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sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
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delete_obj:
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kobject_put(*hugepage_kobj);
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return err;
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}
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static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
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{
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sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
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sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
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kobject_put(hugepage_kobj);
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}
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#else
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static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
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{
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return 0;
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}
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static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
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{
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}
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#endif /* CONFIG_SYSFS */
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|
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static int __init hugepage_init(void)
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{
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int err;
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struct kobject *hugepage_kobj;
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|
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if (!has_transparent_hugepage()) {
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/*
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* Hardware doesn't support hugepages, hence disable
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* DAX PMD support.
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*/
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transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX;
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return -EINVAL;
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}
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|
|
/*
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* hugepages can't be allocated by the buddy allocator
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*/
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MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
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/*
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|
* we use page->mapping and page->index in second tail page
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* as list_head: assuming THP order >= 2
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*/
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MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
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err = hugepage_init_sysfs(&hugepage_kobj);
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if (err)
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goto err_sysfs;
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|
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err = khugepaged_init();
|
|
if (err)
|
|
goto err_slab;
|
|
|
|
err = register_shrinker(&huge_zero_page_shrinker);
|
|
if (err)
|
|
goto err_hzp_shrinker;
|
|
err = register_shrinker(&deferred_split_shrinker);
|
|
if (err)
|
|
goto err_split_shrinker;
|
|
|
|
/*
|
|
* By default disable transparent hugepages on smaller systems,
|
|
* where the extra memory used could hurt more than TLB overhead
|
|
* is likely to save. The admin can still enable it through /sys.
|
|
*/
|
|
if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
|
|
transparent_hugepage_flags = 0;
|
|
return 0;
|
|
}
|
|
|
|
err = start_stop_khugepaged();
|
|
if (err)
|
|
goto err_khugepaged;
|
|
|
|
return 0;
|
|
err_khugepaged:
|
|
unregister_shrinker(&deferred_split_shrinker);
|
|
err_split_shrinker:
|
|
unregister_shrinker(&huge_zero_page_shrinker);
|
|
err_hzp_shrinker:
|
|
khugepaged_destroy();
|
|
err_slab:
|
|
hugepage_exit_sysfs(hugepage_kobj);
|
|
err_sysfs:
|
|
return err;
|
|
}
|
|
subsys_initcall(hugepage_init);
|
|
|
|
static int __init setup_transparent_hugepage(char *str)
|
|
{
|
|
int ret = 0;
|
|
if (!str)
|
|
goto out;
|
|
if (!strcmp(str, "always")) {
|
|
set_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
} else if (!strcmp(str, "madvise")) {
|
|
clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
} else if (!strcmp(str, "never")) {
|
|
clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
|
|
&transparent_hugepage_flags);
|
|
clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
|
|
&transparent_hugepage_flags);
|
|
ret = 1;
|
|
}
|
|
out:
|
|
if (!ret)
|
|
pr_warn("transparent_hugepage= cannot parse, ignored\n");
|
|
return ret;
|
|
}
|
|
__setup("transparent_hugepage=", setup_transparent_hugepage);
|
|
|
|
pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
|
|
{
|
|
if (likely(vma->vm_flags & VM_WRITE))
|
|
pmd = pmd_mkwrite(pmd);
|
|
return pmd;
|
|
}
|
|
|
|
#ifdef CONFIG_MEMCG
|
|
static inline struct deferred_split *get_deferred_split_queue(struct page *page)
|
|
{
|
|
struct mem_cgroup *memcg = page_memcg(compound_head(page));
|
|
struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
|
|
|
|
if (memcg)
|
|
return &memcg->deferred_split_queue;
|
|
else
|
|
return &pgdat->deferred_split_queue;
|
|
}
|
|
#else
|
|
static inline struct deferred_split *get_deferred_split_queue(struct page *page)
|
|
{
|
|
struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
|
|
|
|
return &pgdat->deferred_split_queue;
|
|
}
|
|
#endif
|
|
|
|
void prep_transhuge_page(struct page *page)
|
|
{
|
|
/*
|
|
* we use page->mapping and page->indexlru in second tail page
|
|
* as list_head: assuming THP order >= 2
|
|
*/
|
|
|
|
INIT_LIST_HEAD(page_deferred_list(page));
|
|
set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
|
|
}
|
|
|
|
bool is_transparent_hugepage(struct page *page)
|
|
{
|
|
if (!PageCompound(page))
|
|
return false;
|
|
|
|
page = compound_head(page);
|
|
return is_huge_zero_page(page) ||
|
|
page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
|
|
}
|
|
EXPORT_SYMBOL_GPL(is_transparent_hugepage);
|
|
|
|
static unsigned long __thp_get_unmapped_area(struct file *filp,
|
|
unsigned long addr, unsigned long len,
|
|
loff_t off, unsigned long flags, unsigned long size)
|
|
{
|
|
loff_t off_end = off + len;
|
|
loff_t off_align = round_up(off, size);
|
|
unsigned long len_pad, ret;
|
|
|
|
if (off_end <= off_align || (off_end - off_align) < size)
|
|
return 0;
|
|
|
|
len_pad = len + size;
|
|
if (len_pad < len || (off + len_pad) < off)
|
|
return 0;
|
|
|
|
ret = current->mm->get_unmapped_area(filp, addr, len_pad,
|
|
off >> PAGE_SHIFT, flags);
|
|
|
|
/*
|
|
* The failure might be due to length padding. The caller will retry
|
|
* without the padding.
|
|
*/
|
|
if (IS_ERR_VALUE(ret))
|
|
return 0;
|
|
|
|
/*
|
|
* Do not try to align to THP boundary if allocation at the address
|
|
* hint succeeds.
|
|
*/
|
|
if (ret == addr)
|
|
return addr;
|
|
|
|
ret += (off - ret) & (size - 1);
|
|
return ret;
|
|
}
|
|
|
|
unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
unsigned long ret;
|
|
loff_t off = (loff_t)pgoff << PAGE_SHIFT;
|
|
|
|
if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
|
|
goto out;
|
|
|
|
ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
|
|
if (ret)
|
|
return ret;
|
|
out:
|
|
return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
|
|
|
|
static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
|
|
struct page *page, gfp_t gfp)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
pgtable_t pgtable;
|
|
unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
|
|
vm_fault_t ret = 0;
|
|
|
|
VM_BUG_ON_PAGE(!PageCompound(page), page);
|
|
|
|
if (mem_cgroup_charge(page, vma->vm_mm, gfp)) {
|
|
put_page(page);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
count_vm_event(THP_FAULT_FALLBACK_CHARGE);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
cgroup_throttle_swaprate(page, gfp);
|
|
|
|
pgtable = pte_alloc_one(vma->vm_mm);
|
|
if (unlikely(!pgtable)) {
|
|
ret = VM_FAULT_OOM;
|
|
goto release;
|
|
}
|
|
|
|
clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
|
|
/*
|
|
* The memory barrier inside __SetPageUptodate makes sure that
|
|
* clear_huge_page writes become visible before the set_pmd_at()
|
|
* write.
|
|
*/
|
|
__SetPageUptodate(page);
|
|
|
|
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
|
|
if (unlikely(!pmd_none(*vmf->pmd))) {
|
|
goto unlock_release;
|
|
} else {
|
|
pmd_t entry;
|
|
|
|
ret = check_stable_address_space(vma->vm_mm);
|
|
if (ret)
|
|
goto unlock_release;
|
|
|
|
/* Deliver the page fault to userland */
|
|
if (userfaultfd_missing(vma)) {
|
|
spin_unlock(vmf->ptl);
|
|
put_page(page);
|
|
pte_free(vma->vm_mm, pgtable);
|
|
ret = handle_userfault(vmf, VM_UFFD_MISSING);
|
|
VM_BUG_ON(ret & VM_FAULT_FALLBACK);
|
|
return ret;
|
|
}
|
|
|
|
entry = mk_huge_pmd(page, vma->vm_page_prot);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
page_add_new_anon_rmap(page, vma, haddr, true);
|
|
lru_cache_add_inactive_or_unevictable(page, vma);
|
|
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
|
|
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
|
|
update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
|
|
add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
mm_inc_nr_ptes(vma->vm_mm);
|
|
spin_unlock(vmf->ptl);
|
|
count_vm_event(THP_FAULT_ALLOC);
|
|
count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
|
|
}
|
|
|
|
return 0;
|
|
unlock_release:
|
|
spin_unlock(vmf->ptl);
|
|
release:
|
|
if (pgtable)
|
|
pte_free(vma->vm_mm, pgtable);
|
|
put_page(page);
|
|
return ret;
|
|
|
|
}
|
|
|
|
/*
|
|
* always: directly stall for all thp allocations
|
|
* defer: wake kswapd and fail if not immediately available
|
|
* defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
|
|
* fail if not immediately available
|
|
* madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
|
|
* available
|
|
* never: never stall for any thp allocation
|
|
*/
|
|
gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
|
|
{
|
|
const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
|
|
|
|
/* Always do synchronous compaction */
|
|
if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
|
|
return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
|
|
|
|
/* Kick kcompactd and fail quickly */
|
|
if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
|
|
return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
|
|
|
|
/* Synchronous compaction if madvised, otherwise kick kcompactd */
|
|
if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
|
|
return GFP_TRANSHUGE_LIGHT |
|
|
(vma_madvised ? __GFP_DIRECT_RECLAIM :
|
|
__GFP_KSWAPD_RECLAIM);
|
|
|
|
/* Only do synchronous compaction if madvised */
|
|
if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
|
|
return GFP_TRANSHUGE_LIGHT |
|
|
(vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
|
|
|
|
return GFP_TRANSHUGE_LIGHT;
|
|
}
|
|
|
|
/* Caller must hold page table lock. */
|
|
static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
|
|
struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
|
|
struct page *zero_page)
|
|
{
|
|
pmd_t entry;
|
|
if (!pmd_none(*pmd))
|
|
return;
|
|
entry = mk_pmd(zero_page, vma->vm_page_prot);
|
|
entry = pmd_mkhuge(entry);
|
|
if (pgtable)
|
|
pgtable_trans_huge_deposit(mm, pmd, pgtable);
|
|
set_pmd_at(mm, haddr, pmd, entry);
|
|
mm_inc_nr_ptes(mm);
|
|
}
|
|
|
|
vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
gfp_t gfp;
|
|
struct page *page;
|
|
unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
|
|
|
|
if (!transhuge_vma_suitable(vma, haddr))
|
|
return VM_FAULT_FALLBACK;
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return VM_FAULT_OOM;
|
|
if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
|
|
return VM_FAULT_OOM;
|
|
if (!(vmf->flags & FAULT_FLAG_WRITE) &&
|
|
!mm_forbids_zeropage(vma->vm_mm) &&
|
|
transparent_hugepage_use_zero_page()) {
|
|
pgtable_t pgtable;
|
|
struct page *zero_page;
|
|
vm_fault_t ret;
|
|
pgtable = pte_alloc_one(vma->vm_mm);
|
|
if (unlikely(!pgtable))
|
|
return VM_FAULT_OOM;
|
|
zero_page = mm_get_huge_zero_page(vma->vm_mm);
|
|
if (unlikely(!zero_page)) {
|
|
pte_free(vma->vm_mm, pgtable);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
|
|
ret = 0;
|
|
if (pmd_none(*vmf->pmd)) {
|
|
ret = check_stable_address_space(vma->vm_mm);
|
|
if (ret) {
|
|
spin_unlock(vmf->ptl);
|
|
pte_free(vma->vm_mm, pgtable);
|
|
} else if (userfaultfd_missing(vma)) {
|
|
spin_unlock(vmf->ptl);
|
|
pte_free(vma->vm_mm, pgtable);
|
|
ret = handle_userfault(vmf, VM_UFFD_MISSING);
|
|
VM_BUG_ON(ret & VM_FAULT_FALLBACK);
|
|
} else {
|
|
set_huge_zero_page(pgtable, vma->vm_mm, vma,
|
|
haddr, vmf->pmd, zero_page);
|
|
update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
|
|
spin_unlock(vmf->ptl);
|
|
}
|
|
} else {
|
|
spin_unlock(vmf->ptl);
|
|
pte_free(vma->vm_mm, pgtable);
|
|
}
|
|
return ret;
|
|
}
|
|
gfp = vma_thp_gfp_mask(vma);
|
|
page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
|
|
if (unlikely(!page)) {
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
prep_transhuge_page(page);
|
|
return __do_huge_pmd_anonymous_page(vmf, page, gfp);
|
|
}
|
|
|
|
static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
|
|
pgtable_t pgtable)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pmd_t entry;
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (!pmd_none(*pmd)) {
|
|
if (write) {
|
|
if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
|
|
WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
|
|
goto out_unlock;
|
|
}
|
|
entry = pmd_mkyoung(*pmd);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
|
|
update_mmu_cache_pmd(vma, addr, pmd);
|
|
}
|
|
|
|
goto out_unlock;
|
|
}
|
|
|
|
entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
|
|
if (pfn_t_devmap(pfn))
|
|
entry = pmd_mkdevmap(entry);
|
|
if (write) {
|
|
entry = pmd_mkyoung(pmd_mkdirty(entry));
|
|
entry = maybe_pmd_mkwrite(entry, vma);
|
|
}
|
|
|
|
if (pgtable) {
|
|
pgtable_trans_huge_deposit(mm, pmd, pgtable);
|
|
mm_inc_nr_ptes(mm);
|
|
pgtable = NULL;
|
|
}
|
|
|
|
set_pmd_at(mm, addr, pmd, entry);
|
|
update_mmu_cache_pmd(vma, addr, pmd);
|
|
|
|
out_unlock:
|
|
spin_unlock(ptl);
|
|
if (pgtable)
|
|
pte_free(mm, pgtable);
|
|
}
|
|
|
|
/**
|
|
* vmf_insert_pfn_pmd_prot - insert a pmd size pfn
|
|
* @vmf: Structure describing the fault
|
|
* @pfn: pfn to insert
|
|
* @pgprot: page protection to use
|
|
* @write: whether it's a write fault
|
|
*
|
|
* Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
|
|
* also consult the vmf_insert_mixed_prot() documentation when
|
|
* @pgprot != @vmf->vma->vm_page_prot.
|
|
*
|
|
* Return: vm_fault_t value.
|
|
*/
|
|
vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
|
|
pgprot_t pgprot, bool write)
|
|
{
|
|
unsigned long addr = vmf->address & PMD_MASK;
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
pgtable_t pgtable = NULL;
|
|
|
|
/*
|
|
* If we had pmd_special, we could avoid all these restrictions,
|
|
* but we need to be consistent with PTEs and architectures that
|
|
* can't support a 'special' bit.
|
|
*/
|
|
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
|
|
!pfn_t_devmap(pfn));
|
|
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
|
|
(VM_PFNMAP|VM_MIXEDMAP));
|
|
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
|
|
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
if (arch_needs_pgtable_deposit()) {
|
|
pgtable = pte_alloc_one(vma->vm_mm);
|
|
if (!pgtable)
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
track_pfn_insert(vma, &pgprot, pfn);
|
|
|
|
insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
|
|
|
|
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
|
|
{
|
|
if (likely(vma->vm_flags & VM_WRITE))
|
|
pud = pud_mkwrite(pud);
|
|
return pud;
|
|
}
|
|
|
|
static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
|
|
pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pud_t entry;
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pud_lock(mm, pud);
|
|
if (!pud_none(*pud)) {
|
|
if (write) {
|
|
if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
|
|
WARN_ON_ONCE(!is_huge_zero_pud(*pud));
|
|
goto out_unlock;
|
|
}
|
|
entry = pud_mkyoung(*pud);
|
|
entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
|
|
if (pudp_set_access_flags(vma, addr, pud, entry, 1))
|
|
update_mmu_cache_pud(vma, addr, pud);
|
|
}
|
|
goto out_unlock;
|
|
}
|
|
|
|
entry = pud_mkhuge(pfn_t_pud(pfn, prot));
|
|
if (pfn_t_devmap(pfn))
|
|
entry = pud_mkdevmap(entry);
|
|
if (write) {
|
|
entry = pud_mkyoung(pud_mkdirty(entry));
|
|
entry = maybe_pud_mkwrite(entry, vma);
|
|
}
|
|
set_pud_at(mm, addr, pud, entry);
|
|
update_mmu_cache_pud(vma, addr, pud);
|
|
|
|
out_unlock:
|
|
spin_unlock(ptl);
|
|
}
|
|
|
|
/**
|
|
* vmf_insert_pfn_pud_prot - insert a pud size pfn
|
|
* @vmf: Structure describing the fault
|
|
* @pfn: pfn to insert
|
|
* @pgprot: page protection to use
|
|
* @write: whether it's a write fault
|
|
*
|
|
* Insert a pud size pfn. See vmf_insert_pfn() for additional info and
|
|
* also consult the vmf_insert_mixed_prot() documentation when
|
|
* @pgprot != @vmf->vma->vm_page_prot.
|
|
*
|
|
* Return: vm_fault_t value.
|
|
*/
|
|
vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
|
|
pgprot_t pgprot, bool write)
|
|
{
|
|
unsigned long addr = vmf->address & PUD_MASK;
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
|
|
/*
|
|
* If we had pud_special, we could avoid all these restrictions,
|
|
* but we need to be consistent with PTEs and architectures that
|
|
* can't support a 'special' bit.
|
|
*/
|
|
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
|
|
!pfn_t_devmap(pfn));
|
|
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
|
|
(VM_PFNMAP|VM_MIXEDMAP));
|
|
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
|
|
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
track_pfn_insert(vma, &pgprot, pfn);
|
|
|
|
insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
|
|
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
|
|
|
|
static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, int flags)
|
|
{
|
|
pmd_t _pmd;
|
|
|
|
_pmd = pmd_mkyoung(*pmd);
|
|
if (flags & FOLL_WRITE)
|
|
_pmd = pmd_mkdirty(_pmd);
|
|
if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
|
|
pmd, _pmd, flags & FOLL_WRITE))
|
|
update_mmu_cache_pmd(vma, addr, pmd);
|
|
}
|
|
|
|
struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
|
|
{
|
|
unsigned long pfn = pmd_pfn(*pmd);
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page;
|
|
|
|
assert_spin_locked(pmd_lockptr(mm, pmd));
|
|
|
|
/*
|
|
* When we COW a devmap PMD entry, we split it into PTEs, so we should
|
|
* not be in this function with `flags & FOLL_COW` set.
|
|
*/
|
|
WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
|
|
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
|
|
(FOLL_PIN | FOLL_GET)))
|
|
return NULL;
|
|
|
|
if (flags & FOLL_WRITE && !pmd_write(*pmd))
|
|
return NULL;
|
|
|
|
if (pmd_present(*pmd) && pmd_devmap(*pmd))
|
|
/* pass */;
|
|
else
|
|
return NULL;
|
|
|
|
if (flags & FOLL_TOUCH)
|
|
touch_pmd(vma, addr, pmd, flags);
|
|
|
|
/*
|
|
* device mapped pages can only be returned if the
|
|
* caller will manage the page reference count.
|
|
*/
|
|
if (!(flags & (FOLL_GET | FOLL_PIN)))
|
|
return ERR_PTR(-EEXIST);
|
|
|
|
pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
|
|
*pgmap = get_dev_pagemap(pfn, *pgmap);
|
|
if (!*pgmap)
|
|
return ERR_PTR(-EFAULT);
|
|
page = pfn_to_page(pfn);
|
|
if (!try_grab_page(page, flags))
|
|
page = ERR_PTR(-ENOMEM);
|
|
|
|
return page;
|
|
}
|
|
|
|
int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *dst_ptl, *src_ptl;
|
|
struct page *src_page;
|
|
pmd_t pmd;
|
|
pgtable_t pgtable = NULL;
|
|
int ret = -ENOMEM;
|
|
|
|
/* Skip if can be re-fill on fault */
|
|
if (!vma_is_anonymous(vma))
|
|
return 0;
|
|
|
|
pgtable = pte_alloc_one(dst_mm);
|
|
if (unlikely(!pgtable))
|
|
goto out;
|
|
|
|
dst_ptl = pmd_lock(dst_mm, dst_pmd);
|
|
src_ptl = pmd_lockptr(src_mm, src_pmd);
|
|
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
|
|
|
|
ret = -EAGAIN;
|
|
pmd = *src_pmd;
|
|
|
|
/*
|
|
* Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
|
|
* does not have the VM_UFFD_WP, which means that the uffd
|
|
* fork event is not enabled.
|
|
*/
|
|
if (!(vma->vm_flags & VM_UFFD_WP))
|
|
pmd = pmd_clear_uffd_wp(pmd);
|
|
|
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
|
|
if (unlikely(is_swap_pmd(pmd))) {
|
|
swp_entry_t entry = pmd_to_swp_entry(pmd);
|
|
|
|
VM_BUG_ON(!is_pmd_migration_entry(pmd));
|
|
if (is_write_migration_entry(entry)) {
|
|
make_migration_entry_read(&entry);
|
|
pmd = swp_entry_to_pmd(entry);
|
|
if (pmd_swp_soft_dirty(*src_pmd))
|
|
pmd = pmd_swp_mksoft_dirty(pmd);
|
|
set_pmd_at(src_mm, addr, src_pmd, pmd);
|
|
}
|
|
add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
mm_inc_nr_ptes(dst_mm);
|
|
pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
|
|
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
#endif
|
|
|
|
if (unlikely(!pmd_trans_huge(pmd))) {
|
|
pte_free(dst_mm, pgtable);
|
|
goto out_unlock;
|
|
}
|
|
/*
|
|
* When page table lock is held, the huge zero pmd should not be
|
|
* under splitting since we don't split the page itself, only pmd to
|
|
* a page table.
|
|
*/
|
|
if (is_huge_zero_pmd(pmd)) {
|
|
struct page *zero_page;
|
|
/*
|
|
* 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 = mm_get_huge_zero_page(dst_mm);
|
|
set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
|
|
zero_page);
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
src_page = pmd_page(pmd);
|
|
VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
|
|
|
|
/*
|
|
* If this page is a potentially pinned page, split and retry the fault
|
|
* with smaller page size. Normally this should not happen because the
|
|
* userspace should use MADV_DONTFORK upon pinned regions. This is a
|
|
* best effort that the pinned pages won't be replaced by another
|
|
* random page during the coming copy-on-write.
|
|
*/
|
|
if (unlikely(page_needs_cow_for_dma(vma, src_page))) {
|
|
pte_free(dst_mm, pgtable);
|
|
spin_unlock(src_ptl);
|
|
spin_unlock(dst_ptl);
|
|
__split_huge_pmd(vma, src_pmd, addr, false, NULL);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
get_page(src_page);
|
|
page_dup_rmap(src_page, true);
|
|
add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
|
|
mm_inc_nr_ptes(dst_mm);
|
|
pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
|
|
|
|
pmdp_set_wrprotect(src_mm, addr, src_pmd);
|
|
pmd = pmd_mkold(pmd_wrprotect(pmd));
|
|
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
|
|
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock(src_ptl);
|
|
spin_unlock(dst_ptl);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
|
|
pud_t *pud, int flags)
|
|
{
|
|
pud_t _pud;
|
|
|
|
_pud = pud_mkyoung(*pud);
|
|
if (flags & FOLL_WRITE)
|
|
_pud = pud_mkdirty(_pud);
|
|
if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
|
|
pud, _pud, flags & FOLL_WRITE))
|
|
update_mmu_cache_pud(vma, addr, pud);
|
|
}
|
|
|
|
struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
|
|
pud_t *pud, int flags, struct dev_pagemap **pgmap)
|
|
{
|
|
unsigned long pfn = pud_pfn(*pud);
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page;
|
|
|
|
assert_spin_locked(pud_lockptr(mm, pud));
|
|
|
|
if (flags & FOLL_WRITE && !pud_write(*pud))
|
|
return NULL;
|
|
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
|
|
(FOLL_PIN | FOLL_GET)))
|
|
return NULL;
|
|
|
|
if (pud_present(*pud) && pud_devmap(*pud))
|
|
/* pass */;
|
|
else
|
|
return NULL;
|
|
|
|
if (flags & FOLL_TOUCH)
|
|
touch_pud(vma, addr, pud, flags);
|
|
|
|
/*
|
|
* device mapped pages can only be returned if the
|
|
* caller will manage the page reference count.
|
|
*
|
|
* At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
|
|
*/
|
|
if (!(flags & (FOLL_GET | FOLL_PIN)))
|
|
return ERR_PTR(-EEXIST);
|
|
|
|
pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
|
|
*pgmap = get_dev_pagemap(pfn, *pgmap);
|
|
if (!*pgmap)
|
|
return ERR_PTR(-EFAULT);
|
|
page = pfn_to_page(pfn);
|
|
if (!try_grab_page(page, flags))
|
|
page = ERR_PTR(-ENOMEM);
|
|
|
|
return page;
|
|
}
|
|
|
|
int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *dst_ptl, *src_ptl;
|
|
pud_t pud;
|
|
int ret;
|
|
|
|
dst_ptl = pud_lock(dst_mm, dst_pud);
|
|
src_ptl = pud_lockptr(src_mm, src_pud);
|
|
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
|
|
|
|
ret = -EAGAIN;
|
|
pud = *src_pud;
|
|
if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* When page table lock is held, the huge zero pud should not be
|
|
* under splitting since we don't split the page itself, only pud to
|
|
* a page table.
|
|
*/
|
|
if (is_huge_zero_pud(pud)) {
|
|
/* No huge zero pud yet */
|
|
}
|
|
|
|
/* Please refer to comments in copy_huge_pmd() */
|
|
if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) {
|
|
spin_unlock(src_ptl);
|
|
spin_unlock(dst_ptl);
|
|
__split_huge_pud(vma, src_pud, addr);
|
|
return -EAGAIN;
|
|
}
|
|
|
|
pudp_set_wrprotect(src_mm, addr, src_pud);
|
|
pud = pud_mkold(pud_wrprotect(pud));
|
|
set_pud_at(dst_mm, addr, dst_pud, pud);
|
|
|
|
ret = 0;
|
|
out_unlock:
|
|
spin_unlock(src_ptl);
|
|
spin_unlock(dst_ptl);
|
|
return ret;
|
|
}
|
|
|
|
void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
|
|
{
|
|
pud_t entry;
|
|
unsigned long haddr;
|
|
bool write = vmf->flags & FAULT_FLAG_WRITE;
|
|
|
|
vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
|
|
if (unlikely(!pud_same(*vmf->pud, orig_pud)))
|
|
goto unlock;
|
|
|
|
entry = pud_mkyoung(orig_pud);
|
|
if (write)
|
|
entry = pud_mkdirty(entry);
|
|
haddr = vmf->address & HPAGE_PUD_MASK;
|
|
if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
|
|
update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
|
|
|
|
unlock:
|
|
spin_unlock(vmf->ptl);
|
|
}
|
|
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
|
|
|
|
void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
|
|
{
|
|
pmd_t entry;
|
|
unsigned long haddr;
|
|
bool write = vmf->flags & FAULT_FLAG_WRITE;
|
|
|
|
vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
|
|
if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
|
|
goto unlock;
|
|
|
|
entry = pmd_mkyoung(orig_pmd);
|
|
if (write)
|
|
entry = pmd_mkdirty(entry);
|
|
haddr = vmf->address & HPAGE_PMD_MASK;
|
|
if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
|
|
update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
|
|
|
|
unlock:
|
|
spin_unlock(vmf->ptl);
|
|
}
|
|
|
|
vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct page *page;
|
|
unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
|
|
|
|
vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
|
|
VM_BUG_ON_VMA(!vma->anon_vma, vma);
|
|
|
|
if (is_huge_zero_pmd(orig_pmd))
|
|
goto fallback;
|
|
|
|
spin_lock(vmf->ptl);
|
|
|
|
if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
|
|
spin_unlock(vmf->ptl);
|
|
return 0;
|
|
}
|
|
|
|
page = pmd_page(orig_pmd);
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
|
|
/* Lock page for reuse_swap_page() */
|
|
if (!trylock_page(page)) {
|
|
get_page(page);
|
|
spin_unlock(vmf->ptl);
|
|
lock_page(page);
|
|
spin_lock(vmf->ptl);
|
|
if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
|
|
spin_unlock(vmf->ptl);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
return 0;
|
|
}
|
|
put_page(page);
|
|
}
|
|
|
|
/*
|
|
* We can only reuse the page if nobody else maps the huge page or it's
|
|
* part.
|
|
*/
|
|
if (reuse_swap_page(page, NULL)) {
|
|
pmd_t entry;
|
|
entry = pmd_mkyoung(orig_pmd);
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
|
|
update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
|
|
unlock_page(page);
|
|
spin_unlock(vmf->ptl);
|
|
return VM_FAULT_WRITE;
|
|
}
|
|
|
|
unlock_page(page);
|
|
spin_unlock(vmf->ptl);
|
|
fallback:
|
|
__split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
/*
|
|
* FOLL_FORCE can write to even unwritable pmd's, but only
|
|
* after we've gone through a COW cycle and they are dirty.
|
|
*/
|
|
static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
|
|
{
|
|
return pmd_write(pmd) ||
|
|
((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
|
|
}
|
|
|
|
struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
|
|
unsigned long addr,
|
|
pmd_t *pmd,
|
|
unsigned int flags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page = NULL;
|
|
|
|
assert_spin_locked(pmd_lockptr(mm, pmd));
|
|
|
|
if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
|
|
goto out;
|
|
|
|
/* Avoid dumping huge zero page */
|
|
if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
|
|
return ERR_PTR(-EFAULT);
|
|
|
|
/* Full NUMA hinting faults to serialise migration in fault paths */
|
|
if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
|
|
goto out;
|
|
|
|
page = pmd_page(*pmd);
|
|
VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
|
|
|
|
if (!try_grab_page(page, flags))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
if (flags & FOLL_TOUCH)
|
|
touch_pmd(vma, addr, pmd, flags);
|
|
|
|
if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
|
|
/*
|
|
* We don't mlock() pte-mapped THPs. This way we can avoid
|
|
* leaking mlocked pages into non-VM_LOCKED VMAs.
|
|
*
|
|
* For anon THP:
|
|
*
|
|
* In most cases the pmd is the only mapping of the page as we
|
|
* break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
|
|
* writable private mappings in populate_vma_page_range().
|
|
*
|
|
* The only scenario when we have the page shared here is if we
|
|
* mlocking read-only mapping shared over fork(). We skip
|
|
* mlocking such pages.
|
|
*
|
|
* For file THP:
|
|
*
|
|
* We can expect PageDoubleMap() to be stable under page lock:
|
|
* for file pages we set it in page_add_file_rmap(), which
|
|
* requires page to be locked.
|
|
*/
|
|
|
|
if (PageAnon(page) && compound_mapcount(page) != 1)
|
|
goto skip_mlock;
|
|
if (PageDoubleMap(page) || !page->mapping)
|
|
goto skip_mlock;
|
|
if (!trylock_page(page))
|
|
goto skip_mlock;
|
|
if (page->mapping && !PageDoubleMap(page))
|
|
mlock_vma_page(page);
|
|
unlock_page(page);
|
|
}
|
|
skip_mlock:
|
|
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
|
|
VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
|
|
|
|
out:
|
|
return page;
|
|
}
|
|
|
|
/* NUMA hinting page fault entry point for trans huge pmds */
|
|
vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct page *page;
|
|
unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
|
|
int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
|
|
int target_nid, last_cpupid = -1;
|
|
bool page_locked;
|
|
bool migrated = false;
|
|
bool was_writable;
|
|
int flags = 0;
|
|
|
|
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
|
|
if (unlikely(!pmd_same(pmd, *vmf->pmd)))
|
|
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(*vmf->pmd))) {
|
|
page = pmd_page(*vmf->pmd);
|
|
if (!get_page_unless_zero(page))
|
|
goto out_unlock;
|
|
spin_unlock(vmf->ptl);
|
|
put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
|
|
goto out;
|
|
}
|
|
|
|
page = pmd_page(pmd);
|
|
BUG_ON(is_huge_zero_page(page));
|
|
page_nid = page_to_nid(page);
|
|
last_cpupid = page_cpupid_last(page);
|
|
count_vm_numa_event(NUMA_HINT_FAULTS);
|
|
if (page_nid == this_nid) {
|
|
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
|
|
flags |= TNF_FAULT_LOCAL;
|
|
}
|
|
|
|
/* See similar comment in do_numa_page for explanation */
|
|
if (!pmd_savedwrite(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);
|
|
/* Migration could have started since the pmd_trans_migrating check */
|
|
if (!page_locked) {
|
|
page_nid = NUMA_NO_NODE;
|
|
if (!get_page_unless_zero(page))
|
|
goto out_unlock;
|
|
spin_unlock(vmf->ptl);
|
|
put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
|
|
goto out;
|
|
} else if (target_nid == NUMA_NO_NODE) {
|
|
/* There are no parallel migrations and page is in the right
|
|
* node. Clear the numa hinting info in this pmd.
|
|
*/
|
|
goto clear_pmdnuma;
|
|
}
|
|
|
|
/*
|
|
* Page is misplaced. Page lock serialises migrations. Acquire anon_vma
|
|
* to serialises splits
|
|
*/
|
|
get_page(page);
|
|
spin_unlock(vmf->ptl);
|
|
anon_vma = page_lock_anon_vma_read(page);
|
|
|
|
/* Confirm the PMD did not change while page_table_lock was released */
|
|
spin_lock(vmf->ptl);
|
|
if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page_nid = NUMA_NO_NODE;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* Bail if we fail to protect against THP splits for any reason */
|
|
if (unlikely(!anon_vma)) {
|
|
put_page(page);
|
|
page_nid = NUMA_NO_NODE;
|
|
goto clear_pmdnuma;
|
|
}
|
|
|
|
/*
|
|
* Since we took the NUMA fault, we must have observed the !accessible
|
|
* bit. Make sure all other CPUs agree with that, to avoid them
|
|
* modifying the page we're about to migrate.
|
|
*
|
|
* Must be done under PTL such that we'll observe the relevant
|
|
* inc_tlb_flush_pending().
|
|
*
|
|
* We are not sure a pending tlb flush here is for a huge page
|
|
* mapping or not. Hence use the tlb range variant
|
|
*/
|
|
if (mm_tlb_flush_pending(vma->vm_mm)) {
|
|
flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
|
|
/*
|
|
* change_huge_pmd() released the pmd lock before
|
|
* invalidating the secondary MMUs sharing the primary
|
|
* MMU pagetables (with ->invalidate_range()). The
|
|
* mmu_notifier_invalidate_range_end() (which
|
|
* internally calls ->invalidate_range()) in
|
|
* change_pmd_range() will run after us, so we can't
|
|
* rely on it here and we need an explicit invalidate.
|
|
*/
|
|
mmu_notifier_invalidate_range(vma->vm_mm, haddr,
|
|
haddr + HPAGE_PMD_SIZE);
|
|
}
|
|
|
|
/*
|
|
* Migrate the THP to the requested node, returns with page unlocked
|
|
* and access rights restored.
|
|
*/
|
|
spin_unlock(vmf->ptl);
|
|
|
|
migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
|
|
vmf->pmd, pmd, vmf->address, page, target_nid);
|
|
if (migrated) {
|
|
flags |= TNF_MIGRATED;
|
|
page_nid = target_nid;
|
|
} else
|
|
flags |= TNF_MIGRATE_FAIL;
|
|
|
|
goto out;
|
|
clear_pmdnuma:
|
|
BUG_ON(!PageLocked(page));
|
|
was_writable = pmd_savedwrite(pmd);
|
|
pmd = pmd_modify(pmd, vma->vm_page_prot);
|
|
pmd = pmd_mkyoung(pmd);
|
|
if (was_writable)
|
|
pmd = pmd_mkwrite(pmd);
|
|
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
|
|
update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
|
|
unlock_page(page);
|
|
out_unlock:
|
|
spin_unlock(vmf->ptl);
|
|
|
|
out:
|
|
if (anon_vma)
|
|
page_unlock_anon_vma_read(anon_vma);
|
|
|
|
if (page_nid != NUMA_NO_NODE)
|
|
task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
|
|
flags);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return true if we do MADV_FREE successfully on entire pmd page.
|
|
* Otherwise, return false.
|
|
*/
|
|
bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pmd_t *pmd, unsigned long addr, unsigned long next)
|
|
{
|
|
spinlock_t *ptl;
|
|
pmd_t orig_pmd;
|
|
struct page *page;
|
|
struct mm_struct *mm = tlb->mm;
|
|
bool ret = false;
|
|
|
|
tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
|
|
|
|
ptl = pmd_trans_huge_lock(pmd, vma);
|
|
if (!ptl)
|
|
goto out_unlocked;
|
|
|
|
orig_pmd = *pmd;
|
|
if (is_huge_zero_pmd(orig_pmd))
|
|
goto out;
|
|
|
|
if (unlikely(!pmd_present(orig_pmd))) {
|
|
VM_BUG_ON(thp_migration_supported() &&
|
|
!is_pmd_migration_entry(orig_pmd));
|
|
goto out;
|
|
}
|
|
|
|
page = pmd_page(orig_pmd);
|
|
/*
|
|
* If other processes are mapping this page, we couldn't discard
|
|
* the page unless they all do MADV_FREE so let's skip the page.
|
|
*/
|
|
if (page_mapcount(page) != 1)
|
|
goto out;
|
|
|
|
if (!trylock_page(page))
|
|
goto out;
|
|
|
|
/*
|
|
* If user want to discard part-pages of THP, split it so MADV_FREE
|
|
* will deactivate only them.
|
|
*/
|
|
if (next - addr != HPAGE_PMD_SIZE) {
|
|
get_page(page);
|
|
spin_unlock(ptl);
|
|
split_huge_page(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
goto out_unlocked;
|
|
}
|
|
|
|
if (PageDirty(page))
|
|
ClearPageDirty(page);
|
|
unlock_page(page);
|
|
|
|
if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
|
|
pmdp_invalidate(vma, addr, pmd);
|
|
orig_pmd = pmd_mkold(orig_pmd);
|
|
orig_pmd = pmd_mkclean(orig_pmd);
|
|
|
|
set_pmd_at(mm, addr, pmd, orig_pmd);
|
|
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
|
|
}
|
|
|
|
mark_page_lazyfree(page);
|
|
ret = true;
|
|
out:
|
|
spin_unlock(ptl);
|
|
out_unlocked:
|
|
return ret;
|
|
}
|
|
|
|
static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
|
|
{
|
|
pgtable_t pgtable;
|
|
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pte_free(mm, pgtable);
|
|
mm_dec_nr_ptes(mm);
|
|
}
|
|
|
|
int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pmd_t *pmd, unsigned long addr)
|
|
{
|
|
pmd_t orig_pmd;
|
|
spinlock_t *ptl;
|
|
|
|
tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
|
|
|
|
ptl = __pmd_trans_huge_lock(pmd, vma);
|
|
if (!ptl)
|
|
return 0;
|
|
/*
|
|
* For architectures like ppc64 we look at deposited pgtable
|
|
* when calling pmdp_huge_get_and_clear. So do the
|
|
* pgtable_trans_huge_withdraw after finishing pmdp related
|
|
* operations.
|
|
*/
|
|
orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
|
|
tlb->fullmm);
|
|
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
|
|
if (vma_is_special_huge(vma)) {
|
|
if (arch_needs_pgtable_deposit())
|
|
zap_deposited_table(tlb->mm, pmd);
|
|
spin_unlock(ptl);
|
|
if (is_huge_zero_pmd(orig_pmd))
|
|
tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
|
|
} else if (is_huge_zero_pmd(orig_pmd)) {
|
|
zap_deposited_table(tlb->mm, pmd);
|
|
spin_unlock(ptl);
|
|
tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
|
|
} else {
|
|
struct page *page = NULL;
|
|
int flush_needed = 1;
|
|
|
|
if (pmd_present(orig_pmd)) {
|
|
page = pmd_page(orig_pmd);
|
|
page_remove_rmap(page, true);
|
|
VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
} else if (thp_migration_supported()) {
|
|
swp_entry_t entry;
|
|
|
|
VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
|
|
entry = pmd_to_swp_entry(orig_pmd);
|
|
page = migration_entry_to_page(entry);
|
|
flush_needed = 0;
|
|
} else
|
|
WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
|
|
|
|
if (PageAnon(page)) {
|
|
zap_deposited_table(tlb->mm, pmd);
|
|
add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
|
|
} else {
|
|
if (arch_needs_pgtable_deposit())
|
|
zap_deposited_table(tlb->mm, pmd);
|
|
add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
|
|
}
|
|
|
|
spin_unlock(ptl);
|
|
if (flush_needed)
|
|
tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
#ifndef pmd_move_must_withdraw
|
|
static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
|
|
spinlock_t *old_pmd_ptl,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* With split pmd lock we also need to move preallocated
|
|
* PTE page table if new_pmd is on different PMD page table.
|
|
*
|
|
* We also don't deposit and withdraw tables for file pages.
|
|
*/
|
|
return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
|
|
}
|
|
#endif
|
|
|
|
static pmd_t move_soft_dirty_pmd(pmd_t pmd)
|
|
{
|
|
#ifdef CONFIG_MEM_SOFT_DIRTY
|
|
if (unlikely(is_pmd_migration_entry(pmd)))
|
|
pmd = pmd_swp_mksoft_dirty(pmd);
|
|
else if (pmd_present(pmd))
|
|
pmd = pmd_mksoft_dirty(pmd);
|
|
#endif
|
|
return pmd;
|
|
}
|
|
|
|
bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
|
|
unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
|
|
{
|
|
spinlock_t *old_ptl, *new_ptl;
|
|
pmd_t pmd;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
bool force_flush = false;
|
|
|
|
/*
|
|
* The destination pmd shouldn't be established, free_pgtables()
|
|
* should have release it.
|
|
*/
|
|
if (WARN_ON(!pmd_none(*new_pmd))) {
|
|
VM_BUG_ON(pmd_trans_huge(*new_pmd));
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* We don't have to worry about the ordering of src and dst
|
|
* ptlocks because exclusive mmap_lock prevents deadlock.
|
|
*/
|
|
old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
|
|
if (old_ptl) {
|
|
new_ptl = pmd_lockptr(mm, new_pmd);
|
|
if (new_ptl != old_ptl)
|
|
spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
|
|
pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
|
|
if (pmd_present(pmd))
|
|
force_flush = true;
|
|
VM_BUG_ON(!pmd_none(*new_pmd));
|
|
|
|
if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
|
|
pgtable_t pgtable;
|
|
pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
|
|
pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
|
|
}
|
|
pmd = move_soft_dirty_pmd(pmd);
|
|
set_pmd_at(mm, new_addr, new_pmd, pmd);
|
|
if (force_flush)
|
|
flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
|
|
if (new_ptl != old_ptl)
|
|
spin_unlock(new_ptl);
|
|
spin_unlock(old_ptl);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Returns
|
|
* - 0 if PMD could not be locked
|
|
* - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
|
|
* - HPAGE_PMD_NR if protections changed and TLB flush necessary
|
|
*/
|
|
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
spinlock_t *ptl;
|
|
pmd_t entry;
|
|
bool preserve_write;
|
|
int ret;
|
|
bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
|
|
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
|
|
bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
|
|
|
|
ptl = __pmd_trans_huge_lock(pmd, vma);
|
|
if (!ptl)
|
|
return 0;
|
|
|
|
preserve_write = prot_numa && pmd_write(*pmd);
|
|
ret = 1;
|
|
|
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
|
|
if (is_swap_pmd(*pmd)) {
|
|
swp_entry_t entry = pmd_to_swp_entry(*pmd);
|
|
|
|
VM_BUG_ON(!is_pmd_migration_entry(*pmd));
|
|
if (is_write_migration_entry(entry)) {
|
|
pmd_t newpmd;
|
|
/*
|
|
* A protection check is difficult so
|
|
* just be safe and disable write
|
|
*/
|
|
make_migration_entry_read(&entry);
|
|
newpmd = swp_entry_to_pmd(entry);
|
|
if (pmd_swp_soft_dirty(*pmd))
|
|
newpmd = pmd_swp_mksoft_dirty(newpmd);
|
|
set_pmd_at(mm, addr, pmd, newpmd);
|
|
}
|
|
goto unlock;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Avoid trapping faults against the zero page. The read-only
|
|
* data is likely to be read-cached on the local CPU and
|
|
* local/remote hits to the zero page are not interesting.
|
|
*/
|
|
if (prot_numa && is_huge_zero_pmd(*pmd))
|
|
goto unlock;
|
|
|
|
if (prot_numa && pmd_protnone(*pmd))
|
|
goto unlock;
|
|
|
|
/*
|
|
* In case prot_numa, we are under mmap_read_lock(mm). It's critical
|
|
* to not clear pmd intermittently to avoid race with MADV_DONTNEED
|
|
* which is also under mmap_read_lock(mm):
|
|
*
|
|
* CPU0: CPU1:
|
|
* change_huge_pmd(prot_numa=1)
|
|
* pmdp_huge_get_and_clear_notify()
|
|
* madvise_dontneed()
|
|
* zap_pmd_range()
|
|
* pmd_trans_huge(*pmd) == 0 (without ptl)
|
|
* // skip the pmd
|
|
* set_pmd_at();
|
|
* // pmd is re-established
|
|
*
|
|
* The race makes MADV_DONTNEED miss the huge pmd and don't clear it
|
|
* which may break userspace.
|
|
*
|
|
* pmdp_invalidate() is required to make sure we don't miss
|
|
* dirty/young flags set by hardware.
|
|
*/
|
|
entry = pmdp_invalidate(vma, addr, pmd);
|
|
|
|
entry = pmd_modify(entry, newprot);
|
|
if (preserve_write)
|
|
entry = pmd_mk_savedwrite(entry);
|
|
if (uffd_wp) {
|
|
entry = pmd_wrprotect(entry);
|
|
entry = pmd_mkuffd_wp(entry);
|
|
} else if (uffd_wp_resolve) {
|
|
/*
|
|
* Leave the write bit to be handled by PF interrupt
|
|
* handler, then things like COW could be properly
|
|
* handled.
|
|
*/
|
|
entry = pmd_clear_uffd_wp(entry);
|
|
}
|
|
ret = HPAGE_PMD_NR;
|
|
set_pmd_at(mm, addr, pmd, entry);
|
|
BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
|
|
unlock:
|
|
spin_unlock(ptl);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
|
|
*
|
|
* Note that if it returns page table lock pointer, this routine returns without
|
|
* unlocking page table lock. So callers must unlock it.
|
|
*/
|
|
spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *ptl;
|
|
ptl = pmd_lock(vma->vm_mm, pmd);
|
|
if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
|
|
pmd_devmap(*pmd)))
|
|
return ptl;
|
|
spin_unlock(ptl);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Returns true if a given pud maps a thp, false otherwise.
|
|
*
|
|
* Note that if it returns true, this routine returns without unlocking page
|
|
* table lock. So callers must unlock it.
|
|
*/
|
|
spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
|
|
{
|
|
spinlock_t *ptl;
|
|
|
|
ptl = pud_lock(vma->vm_mm, pud);
|
|
if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
|
|
return ptl;
|
|
spin_unlock(ptl);
|
|
return NULL;
|
|
}
|
|
|
|
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
pud_t *pud, unsigned long addr)
|
|
{
|
|
spinlock_t *ptl;
|
|
|
|
ptl = __pud_trans_huge_lock(pud, vma);
|
|
if (!ptl)
|
|
return 0;
|
|
/*
|
|
* For architectures like ppc64 we look at deposited pgtable
|
|
* when calling pudp_huge_get_and_clear. So do the
|
|
* pgtable_trans_huge_withdraw after finishing pudp related
|
|
* operations.
|
|
*/
|
|
pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
|
|
tlb_remove_pud_tlb_entry(tlb, pud, addr);
|
|
if (vma_is_special_huge(vma)) {
|
|
spin_unlock(ptl);
|
|
/* No zero page support yet */
|
|
} else {
|
|
/* No support for anonymous PUD pages yet */
|
|
BUG();
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
|
|
unsigned long haddr)
|
|
{
|
|
VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
|
|
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
|
|
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
|
|
VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
|
|
|
|
count_vm_event(THP_SPLIT_PUD);
|
|
|
|
pudp_huge_clear_flush_notify(vma, haddr, pud);
|
|
}
|
|
|
|
void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
|
|
unsigned long address)
|
|
{
|
|
spinlock_t *ptl;
|
|
struct mmu_notifier_range range;
|
|
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
|
|
address & HPAGE_PUD_MASK,
|
|
(address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
ptl = pud_lock(vma->vm_mm, pud);
|
|
if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
|
|
goto out;
|
|
__split_huge_pud_locked(vma, pud, range.start);
|
|
|
|
out:
|
|
spin_unlock(ptl);
|
|
/*
|
|
* No need to double call mmu_notifier->invalidate_range() callback as
|
|
* the above pudp_huge_clear_flush_notify() did already call it.
|
|
*/
|
|
mmu_notifier_invalidate_range_only_end(&range);
|
|
}
|
|
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
|
|
|
|
static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
|
|
unsigned long haddr, pmd_t *pmd)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgtable_t pgtable;
|
|
pmd_t _pmd;
|
|
int i;
|
|
|
|
/*
|
|
* Leave pmd empty until pte is filled note that it is fine to delay
|
|
* notification until mmu_notifier_invalidate_range_end() as we are
|
|
* replacing a zero pmd write protected page with a zero pte write
|
|
* protected page.
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
pmdp_huge_clear_flush(vma, haddr, pmd);
|
|
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
|
|
pte_t *pte, entry;
|
|
entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
|
|
entry = pte_mkspecial(entry);
|
|
pte = pte_offset_map(&_pmd, haddr);
|
|
VM_BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, haddr, pte, entry);
|
|
pte_unmap(pte);
|
|
}
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
pmd_populate(mm, pmd, pgtable);
|
|
}
|
|
|
|
static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long haddr, bool freeze)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page;
|
|
pgtable_t pgtable;
|
|
pmd_t old_pmd, _pmd;
|
|
bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
|
|
unsigned long addr;
|
|
int i;
|
|
|
|
VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
|
|
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
|
|
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
|
|
VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
|
|
&& !pmd_devmap(*pmd));
|
|
|
|
count_vm_event(THP_SPLIT_PMD);
|
|
|
|
if (!vma_is_anonymous(vma)) {
|
|
old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
|
|
/*
|
|
* We are going to unmap this huge page. So
|
|
* just go ahead and zap it
|
|
*/
|
|
if (arch_needs_pgtable_deposit())
|
|
zap_deposited_table(mm, pmd);
|
|
if (vma_is_special_huge(vma))
|
|
return;
|
|
if (unlikely(is_pmd_migration_entry(old_pmd))) {
|
|
swp_entry_t entry;
|
|
|
|
entry = pmd_to_swp_entry(old_pmd);
|
|
page = migration_entry_to_page(entry);
|
|
} else {
|
|
page = pmd_page(old_pmd);
|
|
if (!PageDirty(page) && pmd_dirty(old_pmd))
|
|
set_page_dirty(page);
|
|
if (!PageReferenced(page) && pmd_young(old_pmd))
|
|
SetPageReferenced(page);
|
|
page_remove_rmap(page, true);
|
|
put_page(page);
|
|
}
|
|
add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
|
|
return;
|
|
}
|
|
|
|
if (is_huge_zero_pmd(*pmd)) {
|
|
/*
|
|
* FIXME: Do we want to invalidate secondary mmu by calling
|
|
* mmu_notifier_invalidate_range() see comments below inside
|
|
* __split_huge_pmd() ?
|
|
*
|
|
* We are going from a zero huge page write protected to zero
|
|
* small page also write protected so it does not seems useful
|
|
* to invalidate secondary mmu at this time.
|
|
*/
|
|
return __split_huge_zero_page_pmd(vma, haddr, pmd);
|
|
}
|
|
|
|
/*
|
|
* Up to this point the pmd is present and huge and userland has the
|
|
* whole access to the hugepage during the split (which happens in
|
|
* place). If we overwrite the pmd with the not-huge version pointing
|
|
* to the pte here (which of course we could if all CPUs were bug
|
|
* free), userland could trigger a small page size TLB miss on the
|
|
* small sized TLB while the hugepage TLB entry is still established in
|
|
* the huge TLB. Some CPU doesn't like that.
|
|
* See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
|
|
* 383 on page 105. Intel should be safe but is also warns that it's
|
|
* only safe if the permission and cache attributes of the two entries
|
|
* loaded in the two TLB is identical (which should be the case here).
|
|
* But it is generally safer to never allow small and huge TLB entries
|
|
* for the same virtual address to be loaded simultaneously. So instead
|
|
* of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
|
|
* current pmd notpresent (atomically because here the pmd_trans_huge
|
|
* must remain set at all times on the pmd until the split is complete
|
|
* for this pmd), then we flush the SMP TLB and finally we write the
|
|
* non-huge version of the pmd entry with pmd_populate.
|
|
*/
|
|
old_pmd = pmdp_invalidate(vma, haddr, pmd);
|
|
|
|
pmd_migration = is_pmd_migration_entry(old_pmd);
|
|
if (unlikely(pmd_migration)) {
|
|
swp_entry_t entry;
|
|
|
|
entry = pmd_to_swp_entry(old_pmd);
|
|
page = migration_entry_to_page(entry);
|
|
write = is_write_migration_entry(entry);
|
|
young = false;
|
|
soft_dirty = pmd_swp_soft_dirty(old_pmd);
|
|
uffd_wp = pmd_swp_uffd_wp(old_pmd);
|
|
} else {
|
|
page = pmd_page(old_pmd);
|
|
if (pmd_dirty(old_pmd))
|
|
SetPageDirty(page);
|
|
write = pmd_write(old_pmd);
|
|
young = pmd_young(old_pmd);
|
|
soft_dirty = pmd_soft_dirty(old_pmd);
|
|
uffd_wp = pmd_uffd_wp(old_pmd);
|
|
}
|
|
VM_BUG_ON_PAGE(!page_count(page), page);
|
|
page_ref_add(page, HPAGE_PMD_NR - 1);
|
|
|
|
/*
|
|
* Withdraw the table only after we mark the pmd entry invalid.
|
|
* This's critical for some architectures (Power).
|
|
*/
|
|
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
|
|
pmd_populate(mm, &_pmd, pgtable);
|
|
|
|
for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
|
|
pte_t entry, *pte;
|
|
/*
|
|
* Note that NUMA hinting access restrictions are not
|
|
* transferred to avoid any possibility of altering
|
|
* permissions across VMAs.
|
|
*/
|
|
if (freeze || pmd_migration) {
|
|
swp_entry_t swp_entry;
|
|
swp_entry = make_migration_entry(page + i, write);
|
|
entry = swp_entry_to_pte(swp_entry);
|
|
if (soft_dirty)
|
|
entry = pte_swp_mksoft_dirty(entry);
|
|
if (uffd_wp)
|
|
entry = pte_swp_mkuffd_wp(entry);
|
|
} else {
|
|
entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
|
|
entry = maybe_mkwrite(entry, vma);
|
|
if (!write)
|
|
entry = pte_wrprotect(entry);
|
|
if (!young)
|
|
entry = pte_mkold(entry);
|
|
if (soft_dirty)
|
|
entry = pte_mksoft_dirty(entry);
|
|
if (uffd_wp)
|
|
entry = pte_mkuffd_wp(entry);
|
|
}
|
|
pte = pte_offset_map(&_pmd, addr);
|
|
BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, addr, pte, entry);
|
|
if (!pmd_migration)
|
|
atomic_inc(&page[i]._mapcount);
|
|
pte_unmap(pte);
|
|
}
|
|
|
|
if (!pmd_migration) {
|
|
/*
|
|
* Set PG_double_map before dropping compound_mapcount to avoid
|
|
* false-negative page_mapped().
|
|
*/
|
|
if (compound_mapcount(page) > 1 &&
|
|
!TestSetPageDoubleMap(page)) {
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
atomic_inc(&page[i]._mapcount);
|
|
}
|
|
|
|
lock_page_memcg(page);
|
|
if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
|
|
/* Last compound_mapcount is gone. */
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS,
|
|
-HPAGE_PMD_NR);
|
|
if (TestClearPageDoubleMap(page)) {
|
|
/* No need in mapcount reference anymore */
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
atomic_dec(&page[i]._mapcount);
|
|
}
|
|
}
|
|
unlock_page_memcg(page);
|
|
}
|
|
|
|
smp_wmb(); /* make pte visible before pmd */
|
|
pmd_populate(mm, pmd, pgtable);
|
|
|
|
if (freeze) {
|
|
for (i = 0; i < HPAGE_PMD_NR; i++) {
|
|
page_remove_rmap(page + i, false);
|
|
put_page(page + i);
|
|
}
|
|
}
|
|
}
|
|
|
|
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long address, bool freeze, struct page *page)
|
|
{
|
|
spinlock_t *ptl;
|
|
struct mmu_notifier_range range;
|
|
bool do_unlock_page = false;
|
|
pmd_t _pmd;
|
|
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
|
|
address & HPAGE_PMD_MASK,
|
|
(address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
ptl = pmd_lock(vma->vm_mm, pmd);
|
|
|
|
/*
|
|
* If caller asks to setup a migration entries, we need a page to check
|
|
* pmd against. Otherwise we can end up replacing wrong page.
|
|
*/
|
|
VM_BUG_ON(freeze && !page);
|
|
if (page) {
|
|
VM_WARN_ON_ONCE(!PageLocked(page));
|
|
if (page != pmd_page(*pmd))
|
|
goto out;
|
|
}
|
|
|
|
repeat:
|
|
if (pmd_trans_huge(*pmd)) {
|
|
if (!page) {
|
|
page = pmd_page(*pmd);
|
|
/*
|
|
* An anonymous page must be locked, to ensure that a
|
|
* concurrent reuse_swap_page() sees stable mapcount;
|
|
* but reuse_swap_page() is not used on shmem or file,
|
|
* and page lock must not be taken when zap_pmd_range()
|
|
* calls __split_huge_pmd() while i_mmap_lock is held.
|
|
*/
|
|
if (PageAnon(page)) {
|
|
if (unlikely(!trylock_page(page))) {
|
|
get_page(page);
|
|
_pmd = *pmd;
|
|
spin_unlock(ptl);
|
|
lock_page(page);
|
|
spin_lock(ptl);
|
|
if (unlikely(!pmd_same(*pmd, _pmd))) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
page = NULL;
|
|
goto repeat;
|
|
}
|
|
put_page(page);
|
|
}
|
|
do_unlock_page = true;
|
|
}
|
|
}
|
|
if (PageMlocked(page))
|
|
clear_page_mlock(page);
|
|
} else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
|
|
goto out;
|
|
__split_huge_pmd_locked(vma, pmd, range.start, freeze);
|
|
out:
|
|
spin_unlock(ptl);
|
|
if (do_unlock_page)
|
|
unlock_page(page);
|
|
/*
|
|
* No need to double call mmu_notifier->invalidate_range() callback.
|
|
* They are 3 cases to consider inside __split_huge_pmd_locked():
|
|
* 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
|
|
* 2) __split_huge_zero_page_pmd() read only zero page and any write
|
|
* fault will trigger a flush_notify before pointing to a new page
|
|
* (it is fine if the secondary mmu keeps pointing to the old zero
|
|
* page in the meantime)
|
|
* 3) Split a huge pmd into pte pointing to the same page. No need
|
|
* to invalidate secondary tlb entry they are all still valid.
|
|
* any further changes to individual pte will notify. So no need
|
|
* to call mmu_notifier->invalidate_range()
|
|
*/
|
|
mmu_notifier_invalidate_range_only_end(&range);
|
|
}
|
|
|
|
void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
|
|
bool freeze, struct page *page)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
|
|
pgd = pgd_offset(vma->vm_mm, address);
|
|
if (!pgd_present(*pgd))
|
|
return;
|
|
|
|
p4d = p4d_offset(pgd, address);
|
|
if (!p4d_present(*p4d))
|
|
return;
|
|
|
|
pud = pud_offset(p4d, address);
|
|
if (!pud_present(*pud))
|
|
return;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
|
|
__split_huge_pmd(vma, pmd, address, freeze, page);
|
|
}
|
|
|
|
static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
/*
|
|
* If the new address isn't hpage aligned and it could previously
|
|
* contain an hugepage: check if we need to split an huge pmd.
|
|
*/
|
|
if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
|
|
range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
|
|
ALIGN(address, HPAGE_PMD_SIZE)))
|
|
split_huge_pmd_address(vma, address, false, NULL);
|
|
}
|
|
|
|
void vma_adjust_trans_huge(struct vm_area_struct *vma,
|
|
unsigned long start,
|
|
unsigned long end,
|
|
long adjust_next)
|
|
{
|
|
/* Check if we need to split start first. */
|
|
split_huge_pmd_if_needed(vma, start);
|
|
|
|
/* Check if we need to split end next. */
|
|
split_huge_pmd_if_needed(vma, end);
|
|
|
|
/*
|
|
* If we're also updating the vma->vm_next->vm_start,
|
|
* check if we need to split it.
|
|
*/
|
|
if (adjust_next > 0) {
|
|
struct vm_area_struct *next = vma->vm_next;
|
|
unsigned long nstart = next->vm_start;
|
|
nstart += adjust_next;
|
|
split_huge_pmd_if_needed(next, nstart);
|
|
}
|
|
}
|
|
|
|
static void unmap_page(struct page *page)
|
|
{
|
|
enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_SYNC |
|
|
TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
|
|
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
|
|
if (PageAnon(page))
|
|
ttu_flags |= TTU_SPLIT_FREEZE;
|
|
|
|
try_to_unmap(page, ttu_flags);
|
|
|
|
VM_WARN_ON_ONCE_PAGE(page_mapped(page), page);
|
|
}
|
|
|
|
static void remap_page(struct page *page, unsigned int nr)
|
|
{
|
|
int i;
|
|
if (PageTransHuge(page)) {
|
|
remove_migration_ptes(page, page, true);
|
|
} else {
|
|
for (i = 0; i < nr; i++)
|
|
remove_migration_ptes(page + i, page + i, true);
|
|
}
|
|
}
|
|
|
|
static void lru_add_page_tail(struct page *head, struct page *tail,
|
|
struct lruvec *lruvec, struct list_head *list)
|
|
{
|
|
VM_BUG_ON_PAGE(!PageHead(head), head);
|
|
VM_BUG_ON_PAGE(PageCompound(tail), head);
|
|
VM_BUG_ON_PAGE(PageLRU(tail), head);
|
|
lockdep_assert_held(&lruvec->lru_lock);
|
|
|
|
if (list) {
|
|
/* page reclaim is reclaiming a huge page */
|
|
VM_WARN_ON(PageLRU(head));
|
|
get_page(tail);
|
|
list_add_tail(&tail->lru, list);
|
|
} else {
|
|
/* head is still on lru (and we have it frozen) */
|
|
VM_WARN_ON(!PageLRU(head));
|
|
SetPageLRU(tail);
|
|
list_add_tail(&tail->lru, &head->lru);
|
|
}
|
|
}
|
|
|
|
static void __split_huge_page_tail(struct page *head, int tail,
|
|
struct lruvec *lruvec, struct list_head *list)
|
|
{
|
|
struct page *page_tail = head + tail;
|
|
|
|
VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
|
|
|
|
/*
|
|
* Clone page flags before unfreezing refcount.
|
|
*
|
|
* After successful get_page_unless_zero() might follow flags change,
|
|
* for example lock_page() which set PG_waiters.
|
|
*/
|
|
page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
|
|
page_tail->flags |= (head->flags &
|
|
((1L << PG_referenced) |
|
|
(1L << PG_swapbacked) |
|
|
(1L << PG_swapcache) |
|
|
(1L << PG_mlocked) |
|
|
(1L << PG_uptodate) |
|
|
(1L << PG_active) |
|
|
(1L << PG_workingset) |
|
|
(1L << PG_locked) |
|
|
(1L << PG_unevictable) |
|
|
#ifdef CONFIG_64BIT
|
|
(1L << PG_arch_2) |
|
|
#endif
|
|
(1L << PG_dirty)));
|
|
|
|
/* ->mapping in first tail page is compound_mapcount */
|
|
VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
|
|
page_tail);
|
|
page_tail->mapping = head->mapping;
|
|
page_tail->index = head->index + tail;
|
|
|
|
/* Page flags must be visible before we make the page non-compound. */
|
|
smp_wmb();
|
|
|
|
/*
|
|
* Clear PageTail before unfreezing page refcount.
|
|
*
|
|
* After successful get_page_unless_zero() might follow put_page()
|
|
* which needs correct compound_head().
|
|
*/
|
|
clear_compound_head(page_tail);
|
|
|
|
/* Finally unfreeze refcount. Additional reference from page cache. */
|
|
page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
|
|
PageSwapCache(head)));
|
|
|
|
if (page_is_young(head))
|
|
set_page_young(page_tail);
|
|
if (page_is_idle(head))
|
|
set_page_idle(page_tail);
|
|
|
|
page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
|
|
|
|
/*
|
|
* always add to the tail because some iterators expect new
|
|
* pages to show after the currently processed elements - e.g.
|
|
* migrate_pages
|
|
*/
|
|
lru_add_page_tail(head, page_tail, lruvec, list);
|
|
}
|
|
|
|
static void __split_huge_page(struct page *page, struct list_head *list,
|
|
pgoff_t end)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
struct lruvec *lruvec;
|
|
struct address_space *swap_cache = NULL;
|
|
unsigned long offset = 0;
|
|
unsigned int nr = thp_nr_pages(head);
|
|
int i;
|
|
|
|
/* complete memcg works before add pages to LRU */
|
|
split_page_memcg(head, nr);
|
|
|
|
if (PageAnon(head) && PageSwapCache(head)) {
|
|
swp_entry_t entry = { .val = page_private(head) };
|
|
|
|
offset = swp_offset(entry);
|
|
swap_cache = swap_address_space(entry);
|
|
xa_lock(&swap_cache->i_pages);
|
|
}
|
|
|
|
/* lock lru list/PageCompound, ref frozen by page_ref_freeze */
|
|
lruvec = lock_page_lruvec(head);
|
|
|
|
for (i = nr - 1; i >= 1; i--) {
|
|
__split_huge_page_tail(head, i, lruvec, list);
|
|
/* Some pages can be beyond i_size: drop them from page cache */
|
|
if (head[i].index >= end) {
|
|
ClearPageDirty(head + i);
|
|
__delete_from_page_cache(head + i, NULL);
|
|
if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
|
|
shmem_uncharge(head->mapping->host, 1);
|
|
put_page(head + i);
|
|
} else if (!PageAnon(page)) {
|
|
__xa_store(&head->mapping->i_pages, head[i].index,
|
|
head + i, 0);
|
|
} else if (swap_cache) {
|
|
__xa_store(&swap_cache->i_pages, offset + i,
|
|
head + i, 0);
|
|
}
|
|
}
|
|
|
|
ClearPageCompound(head);
|
|
unlock_page_lruvec(lruvec);
|
|
/* Caller disabled irqs, so they are still disabled here */
|
|
|
|
split_page_owner(head, nr);
|
|
|
|
/* See comment in __split_huge_page_tail() */
|
|
if (PageAnon(head)) {
|
|
/* Additional pin to swap cache */
|
|
if (PageSwapCache(head)) {
|
|
page_ref_add(head, 2);
|
|
xa_unlock(&swap_cache->i_pages);
|
|
} else {
|
|
page_ref_inc(head);
|
|
}
|
|
} else {
|
|
/* Additional pin to page cache */
|
|
page_ref_add(head, 2);
|
|
xa_unlock(&head->mapping->i_pages);
|
|
}
|
|
local_irq_enable();
|
|
|
|
remap_page(head, nr);
|
|
|
|
if (PageSwapCache(head)) {
|
|
swp_entry_t entry = { .val = page_private(head) };
|
|
|
|
split_swap_cluster(entry);
|
|
}
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *subpage = head + i;
|
|
if (subpage == page)
|
|
continue;
|
|
unlock_page(subpage);
|
|
|
|
/*
|
|
* Subpages may be freed if there wasn't any mapping
|
|
* like if add_to_swap() is running on a lru page that
|
|
* had its mapping zapped. And freeing these pages
|
|
* requires taking the lru_lock so we do the put_page
|
|
* of the tail pages after the split is complete.
|
|
*/
|
|
put_page(subpage);
|
|
}
|
|
}
|
|
|
|
int total_mapcount(struct page *page)
|
|
{
|
|
int i, compound, nr, ret;
|
|
|
|
VM_BUG_ON_PAGE(PageTail(page), page);
|
|
|
|
if (likely(!PageCompound(page)))
|
|
return atomic_read(&page->_mapcount) + 1;
|
|
|
|
compound = compound_mapcount(page);
|
|
nr = compound_nr(page);
|
|
if (PageHuge(page))
|
|
return compound;
|
|
ret = compound;
|
|
for (i = 0; i < nr; i++)
|
|
ret += atomic_read(&page[i]._mapcount) + 1;
|
|
/* File pages has compound_mapcount included in _mapcount */
|
|
if (!PageAnon(page))
|
|
return ret - compound * nr;
|
|
if (PageDoubleMap(page))
|
|
ret -= nr;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This calculates accurately how many mappings a transparent hugepage
|
|
* has (unlike page_mapcount() which isn't fully accurate). This full
|
|
* accuracy is primarily needed to know if copy-on-write faults can
|
|
* reuse the page and change the mapping to read-write instead of
|
|
* copying them. At the same time this returns the total_mapcount too.
|
|
*
|
|
* The function returns the highest mapcount any one of the subpages
|
|
* has. If the return value is one, even if different processes are
|
|
* mapping different subpages of the transparent hugepage, they can
|
|
* all reuse it, because each process is reusing a different subpage.
|
|
*
|
|
* The total_mapcount is instead counting all virtual mappings of the
|
|
* subpages. If the total_mapcount is equal to "one", it tells the
|
|
* caller all mappings belong to the same "mm" and in turn the
|
|
* anon_vma of the transparent hugepage can become the vma->anon_vma
|
|
* local one as no other process may be mapping any of the subpages.
|
|
*
|
|
* It would be more accurate to replace page_mapcount() with
|
|
* page_trans_huge_mapcount(), however we only use
|
|
* page_trans_huge_mapcount() in the copy-on-write faults where we
|
|
* need full accuracy to avoid breaking page pinning, because
|
|
* page_trans_huge_mapcount() is slower than page_mapcount().
|
|
*/
|
|
int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
|
|
{
|
|
int i, ret, _total_mapcount, mapcount;
|
|
|
|
/* hugetlbfs shouldn't call it */
|
|
VM_BUG_ON_PAGE(PageHuge(page), page);
|
|
|
|
if (likely(!PageTransCompound(page))) {
|
|
mapcount = atomic_read(&page->_mapcount) + 1;
|
|
if (total_mapcount)
|
|
*total_mapcount = mapcount;
|
|
return mapcount;
|
|
}
|
|
|
|
page = compound_head(page);
|
|
|
|
_total_mapcount = ret = 0;
|
|
for (i = 0; i < thp_nr_pages(page); i++) {
|
|
mapcount = atomic_read(&page[i]._mapcount) + 1;
|
|
ret = max(ret, mapcount);
|
|
_total_mapcount += mapcount;
|
|
}
|
|
if (PageDoubleMap(page)) {
|
|
ret -= 1;
|
|
_total_mapcount -= thp_nr_pages(page);
|
|
}
|
|
mapcount = compound_mapcount(page);
|
|
ret += mapcount;
|
|
_total_mapcount += mapcount;
|
|
if (total_mapcount)
|
|
*total_mapcount = _total_mapcount;
|
|
return ret;
|
|
}
|
|
|
|
/* Racy check whether the huge page can be split */
|
|
bool can_split_huge_page(struct page *page, int *pextra_pins)
|
|
{
|
|
int extra_pins;
|
|
|
|
/* Additional pins from page cache */
|
|
if (PageAnon(page))
|
|
extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
|
|
else
|
|
extra_pins = thp_nr_pages(page);
|
|
if (pextra_pins)
|
|
*pextra_pins = extra_pins;
|
|
return total_mapcount(page) == page_count(page) - extra_pins - 1;
|
|
}
|
|
|
|
/*
|
|
* This function splits huge page into normal pages. @page can point to any
|
|
* subpage of huge page to split. Split doesn't change the position of @page.
|
|
*
|
|
* Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
|
|
* The huge page must be locked.
|
|
*
|
|
* If @list is null, tail pages will be added to LRU list, otherwise, to @list.
|
|
*
|
|
* Both head page and tail pages will inherit mapping, flags, and so on from
|
|
* the hugepage.
|
|
*
|
|
* GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
|
|
* they are not mapped.
|
|
*
|
|
* Returns 0 if the hugepage is split successfully.
|
|
* Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
|
|
* us.
|
|
*/
|
|
int split_huge_page_to_list(struct page *page, struct list_head *list)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
struct deferred_split *ds_queue = get_deferred_split_queue(head);
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct address_space *mapping = NULL;
|
|
int extra_pins, ret;
|
|
pgoff_t end;
|
|
|
|
VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
|
|
VM_BUG_ON_PAGE(!PageLocked(head), head);
|
|
VM_BUG_ON_PAGE(!PageCompound(head), head);
|
|
|
|
if (PageWriteback(head))
|
|
return -EBUSY;
|
|
|
|
if (PageAnon(head)) {
|
|
/*
|
|
* The caller does not necessarily hold an mmap_lock that would
|
|
* prevent the anon_vma disappearing so we first we take a
|
|
* reference to it and then lock the anon_vma for write. This
|
|
* is similar to page_lock_anon_vma_read except the write lock
|
|
* is taken to serialise against parallel split or collapse
|
|
* operations.
|
|
*/
|
|
anon_vma = page_get_anon_vma(head);
|
|
if (!anon_vma) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
end = -1;
|
|
mapping = NULL;
|
|
anon_vma_lock_write(anon_vma);
|
|
} else {
|
|
mapping = head->mapping;
|
|
|
|
/* Truncated ? */
|
|
if (!mapping) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
|
|
anon_vma = NULL;
|
|
i_mmap_lock_read(mapping);
|
|
|
|
/*
|
|
*__split_huge_page() may need to trim off pages beyond EOF:
|
|
* but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
|
|
* which cannot be nested inside the page tree lock. So note
|
|
* end now: i_size itself may be changed at any moment, but
|
|
* head page lock is good enough to serialize the trimming.
|
|
*/
|
|
end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
|
|
}
|
|
|
|
/*
|
|
* Racy check if we can split the page, before unmap_page() will
|
|
* split PMDs
|
|
*/
|
|
if (!can_split_huge_page(head, &extra_pins)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
unmap_page(head);
|
|
|
|
/* block interrupt reentry in xa_lock and spinlock */
|
|
local_irq_disable();
|
|
if (mapping) {
|
|
XA_STATE(xas, &mapping->i_pages, page_index(head));
|
|
|
|
/*
|
|
* Check if the head page is present in page cache.
|
|
* We assume all tail are present too, if head is there.
|
|
*/
|
|
xa_lock(&mapping->i_pages);
|
|
if (xas_load(&xas) != head)
|
|
goto fail;
|
|
}
|
|
|
|
/* Prevent deferred_split_scan() touching ->_refcount */
|
|
spin_lock(&ds_queue->split_queue_lock);
|
|
if (page_ref_freeze(head, 1 + extra_pins)) {
|
|
if (!list_empty(page_deferred_list(head))) {
|
|
ds_queue->split_queue_len--;
|
|
list_del(page_deferred_list(head));
|
|
}
|
|
spin_unlock(&ds_queue->split_queue_lock);
|
|
if (mapping) {
|
|
int nr = thp_nr_pages(head);
|
|
|
|
if (PageSwapBacked(head))
|
|
__mod_lruvec_page_state(head, NR_SHMEM_THPS,
|
|
-nr);
|
|
else
|
|
__mod_lruvec_page_state(head, NR_FILE_THPS,
|
|
-nr);
|
|
}
|
|
|
|
__split_huge_page(page, list, end);
|
|
ret = 0;
|
|
} else {
|
|
spin_unlock(&ds_queue->split_queue_lock);
|
|
fail:
|
|
if (mapping)
|
|
xa_unlock(&mapping->i_pages);
|
|
local_irq_enable();
|
|
remap_page(head, thp_nr_pages(head));
|
|
ret = -EBUSY;
|
|
}
|
|
|
|
out_unlock:
|
|
if (anon_vma) {
|
|
anon_vma_unlock_write(anon_vma);
|
|
put_anon_vma(anon_vma);
|
|
}
|
|
if (mapping)
|
|
i_mmap_unlock_read(mapping);
|
|
out:
|
|
count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
|
|
return ret;
|
|
}
|
|
|
|
void free_transhuge_page(struct page *page)
|
|
{
|
|
struct deferred_split *ds_queue = get_deferred_split_queue(page);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
|
|
if (!list_empty(page_deferred_list(page))) {
|
|
ds_queue->split_queue_len--;
|
|
list_del(page_deferred_list(page));
|
|
}
|
|
spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
|
|
free_compound_page(page);
|
|
}
|
|
|
|
void deferred_split_huge_page(struct page *page)
|
|
{
|
|
struct deferred_split *ds_queue = get_deferred_split_queue(page);
|
|
#ifdef CONFIG_MEMCG
|
|
struct mem_cgroup *memcg = page_memcg(compound_head(page));
|
|
#endif
|
|
unsigned long flags;
|
|
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
|
|
/*
|
|
* The try_to_unmap() in page reclaim path might reach here too,
|
|
* this may cause a race condition to corrupt deferred split queue.
|
|
* And, if page reclaim is already handling the same page, it is
|
|
* unnecessary to handle it again in shrinker.
|
|
*
|
|
* Check PageSwapCache to determine if the page is being
|
|
* handled by page reclaim since THP swap would add the page into
|
|
* swap cache before calling try_to_unmap().
|
|
*/
|
|
if (PageSwapCache(page))
|
|
return;
|
|
|
|
spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
|
|
if (list_empty(page_deferred_list(page))) {
|
|
count_vm_event(THP_DEFERRED_SPLIT_PAGE);
|
|
list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
|
|
ds_queue->split_queue_len++;
|
|
#ifdef CONFIG_MEMCG
|
|
if (memcg)
|
|
set_shrinker_bit(memcg, page_to_nid(page),
|
|
deferred_split_shrinker.id);
|
|
#endif
|
|
}
|
|
spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
|
|
}
|
|
|
|
static unsigned long deferred_split_count(struct shrinker *shrink,
|
|
struct shrink_control *sc)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(sc->nid);
|
|
struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
|
|
|
|
#ifdef CONFIG_MEMCG
|
|
if (sc->memcg)
|
|
ds_queue = &sc->memcg->deferred_split_queue;
|
|
#endif
|
|
return READ_ONCE(ds_queue->split_queue_len);
|
|
}
|
|
|
|
static unsigned long deferred_split_scan(struct shrinker *shrink,
|
|
struct shrink_control *sc)
|
|
{
|
|
struct pglist_data *pgdata = NODE_DATA(sc->nid);
|
|
struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
|
|
unsigned long flags;
|
|
LIST_HEAD(list), *pos, *next;
|
|
struct page *page;
|
|
int split = 0;
|
|
|
|
#ifdef CONFIG_MEMCG
|
|
if (sc->memcg)
|
|
ds_queue = &sc->memcg->deferred_split_queue;
|
|
#endif
|
|
|
|
spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
|
|
/* Take pin on all head pages to avoid freeing them under us */
|
|
list_for_each_safe(pos, next, &ds_queue->split_queue) {
|
|
page = list_entry((void *)pos, struct page, mapping);
|
|
page = compound_head(page);
|
|
if (get_page_unless_zero(page)) {
|
|
list_move(page_deferred_list(page), &list);
|
|
} else {
|
|
/* We lost race with put_compound_page() */
|
|
list_del_init(page_deferred_list(page));
|
|
ds_queue->split_queue_len--;
|
|
}
|
|
if (!--sc->nr_to_scan)
|
|
break;
|
|
}
|
|
spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
|
|
|
|
list_for_each_safe(pos, next, &list) {
|
|
page = list_entry((void *)pos, struct page, mapping);
|
|
if (!trylock_page(page))
|
|
goto next;
|
|
/* split_huge_page() removes page from list on success */
|
|
if (!split_huge_page(page))
|
|
split++;
|
|
unlock_page(page);
|
|
next:
|
|
put_page(page);
|
|
}
|
|
|
|
spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
|
|
list_splice_tail(&list, &ds_queue->split_queue);
|
|
spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
|
|
|
|
/*
|
|
* Stop shrinker if we didn't split any page, but the queue is empty.
|
|
* This can happen if pages were freed under us.
|
|
*/
|
|
if (!split && list_empty(&ds_queue->split_queue))
|
|
return SHRINK_STOP;
|
|
return split;
|
|
}
|
|
|
|
static struct shrinker deferred_split_shrinker = {
|
|
.count_objects = deferred_split_count,
|
|
.scan_objects = deferred_split_scan,
|
|
.seeks = DEFAULT_SEEKS,
|
|
.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
|
|
SHRINKER_NONSLAB,
|
|
};
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
static void split_huge_pages_all(void)
|
|
{
|
|
struct zone *zone;
|
|
struct page *page;
|
|
unsigned long pfn, max_zone_pfn;
|
|
unsigned long total = 0, split = 0;
|
|
|
|
pr_debug("Split all THPs\n");
|
|
for_each_populated_zone(zone) {
|
|
max_zone_pfn = zone_end_pfn(zone);
|
|
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
|
|
if (!pfn_valid(pfn))
|
|
continue;
|
|
|
|
page = pfn_to_page(pfn);
|
|
if (!get_page_unless_zero(page))
|
|
continue;
|
|
|
|
if (zone != page_zone(page))
|
|
goto next;
|
|
|
|
if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
|
|
goto next;
|
|
|
|
total++;
|
|
lock_page(page);
|
|
if (!split_huge_page(page))
|
|
split++;
|
|
unlock_page(page);
|
|
next:
|
|
put_page(page);
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
pr_debug("%lu of %lu THP split\n", split, total);
|
|
}
|
|
|
|
static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
|
|
{
|
|
return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
|
|
is_vm_hugetlb_page(vma);
|
|
}
|
|
|
|
static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
|
|
unsigned long vaddr_end)
|
|
{
|
|
int ret = 0;
|
|
struct task_struct *task;
|
|
struct mm_struct *mm;
|
|
unsigned long total = 0, split = 0;
|
|
unsigned long addr;
|
|
|
|
vaddr_start &= PAGE_MASK;
|
|
vaddr_end &= PAGE_MASK;
|
|
|
|
/* Find the task_struct from pid */
|
|
rcu_read_lock();
|
|
task = find_task_by_vpid(pid);
|
|
if (!task) {
|
|
rcu_read_unlock();
|
|
ret = -ESRCH;
|
|
goto out;
|
|
}
|
|
get_task_struct(task);
|
|
rcu_read_unlock();
|
|
|
|
/* Find the mm_struct */
|
|
mm = get_task_mm(task);
|
|
put_task_struct(task);
|
|
|
|
if (!mm) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
|
|
pid, vaddr_start, vaddr_end);
|
|
|
|
mmap_read_lock(mm);
|
|
/*
|
|
* always increase addr by PAGE_SIZE, since we could have a PTE page
|
|
* table filled with PTE-mapped THPs, each of which is distinct.
|
|
*/
|
|
for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
|
|
struct vm_area_struct *vma = find_vma(mm, addr);
|
|
unsigned int follflags;
|
|
struct page *page;
|
|
|
|
if (!vma || addr < vma->vm_start)
|
|
break;
|
|
|
|
/* skip special VMA and hugetlb VMA */
|
|
if (vma_not_suitable_for_thp_split(vma)) {
|
|
addr = vma->vm_end;
|
|
continue;
|
|
}
|
|
|
|
/* FOLL_DUMP to ignore special (like zero) pages */
|
|
follflags = FOLL_GET | FOLL_DUMP;
|
|
page = follow_page(vma, addr, follflags);
|
|
|
|
if (IS_ERR(page))
|
|
continue;
|
|
if (!page)
|
|
continue;
|
|
|
|
if (!is_transparent_hugepage(page))
|
|
goto next;
|
|
|
|
total++;
|
|
if (!can_split_huge_page(compound_head(page), NULL))
|
|
goto next;
|
|
|
|
if (!trylock_page(page))
|
|
goto next;
|
|
|
|
if (!split_huge_page(page))
|
|
split++;
|
|
|
|
unlock_page(page);
|
|
next:
|
|
put_page(page);
|
|
cond_resched();
|
|
}
|
|
mmap_read_unlock(mm);
|
|
mmput(mm);
|
|
|
|
pr_debug("%lu of %lu THP split\n", split, total);
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
|
|
pgoff_t off_end)
|
|
{
|
|
struct filename *file;
|
|
struct file *candidate;
|
|
struct address_space *mapping;
|
|
int ret = -EINVAL;
|
|
pgoff_t index;
|
|
int nr_pages = 1;
|
|
unsigned long total = 0, split = 0;
|
|
|
|
file = getname_kernel(file_path);
|
|
if (IS_ERR(file))
|
|
return ret;
|
|
|
|
candidate = file_open_name(file, O_RDONLY, 0);
|
|
if (IS_ERR(candidate))
|
|
goto out;
|
|
|
|
pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
|
|
file_path, off_start, off_end);
|
|
|
|
mapping = candidate->f_mapping;
|
|
|
|
for (index = off_start; index < off_end; index += nr_pages) {
|
|
struct page *fpage = pagecache_get_page(mapping, index,
|
|
FGP_ENTRY | FGP_HEAD, 0);
|
|
|
|
nr_pages = 1;
|
|
if (xa_is_value(fpage) || !fpage)
|
|
continue;
|
|
|
|
if (!is_transparent_hugepage(fpage))
|
|
goto next;
|
|
|
|
total++;
|
|
nr_pages = thp_nr_pages(fpage);
|
|
|
|
if (!trylock_page(fpage))
|
|
goto next;
|
|
|
|
if (!split_huge_page(fpage))
|
|
split++;
|
|
|
|
unlock_page(fpage);
|
|
next:
|
|
put_page(fpage);
|
|
cond_resched();
|
|
}
|
|
|
|
filp_close(candidate, NULL);
|
|
ret = 0;
|
|
|
|
pr_debug("%lu of %lu file-backed THP split\n", split, total);
|
|
out:
|
|
putname(file);
|
|
return ret;
|
|
}
|
|
|
|
#define MAX_INPUT_BUF_SZ 255
|
|
|
|
static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
|
|
size_t count, loff_t *ppops)
|
|
{
|
|
static DEFINE_MUTEX(split_debug_mutex);
|
|
ssize_t ret;
|
|
/* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
|
|
char input_buf[MAX_INPUT_BUF_SZ];
|
|
int pid;
|
|
unsigned long vaddr_start, vaddr_end;
|
|
|
|
ret = mutex_lock_interruptible(&split_debug_mutex);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = -EFAULT;
|
|
|
|
memset(input_buf, 0, MAX_INPUT_BUF_SZ);
|
|
if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
|
|
goto out;
|
|
|
|
input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
|
|
|
|
if (input_buf[0] == '/') {
|
|
char *tok;
|
|
char *buf = input_buf;
|
|
char file_path[MAX_INPUT_BUF_SZ];
|
|
pgoff_t off_start = 0, off_end = 0;
|
|
size_t input_len = strlen(input_buf);
|
|
|
|
tok = strsep(&buf, ",");
|
|
if (tok) {
|
|
strncpy(file_path, tok, MAX_INPUT_BUF_SZ);
|
|
} else {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
|
|
if (ret != 2) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
ret = split_huge_pages_in_file(file_path, off_start, off_end);
|
|
if (!ret)
|
|
ret = input_len;
|
|
|
|
goto out;
|
|
}
|
|
|
|
ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
|
|
if (ret == 1 && pid == 1) {
|
|
split_huge_pages_all();
|
|
ret = strlen(input_buf);
|
|
goto out;
|
|
} else if (ret != 3) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
|
|
if (!ret)
|
|
ret = strlen(input_buf);
|
|
out:
|
|
mutex_unlock(&split_debug_mutex);
|
|
return ret;
|
|
|
|
}
|
|
|
|
static const struct file_operations split_huge_pages_fops = {
|
|
.owner = THIS_MODULE,
|
|
.write = split_huge_pages_write,
|
|
.llseek = no_llseek,
|
|
};
|
|
|
|
static int __init split_huge_pages_debugfs(void)
|
|
{
|
|
debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
|
|
&split_huge_pages_fops);
|
|
return 0;
|
|
}
|
|
late_initcall(split_huge_pages_debugfs);
|
|
#endif
|
|
|
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
|
|
void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
|
|
struct page *page)
|
|
{
|
|
struct vm_area_struct *vma = pvmw->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long address = pvmw->address;
|
|
pmd_t pmdval;
|
|
swp_entry_t entry;
|
|
pmd_t pmdswp;
|
|
|
|
if (!(pvmw->pmd && !pvmw->pte))
|
|
return;
|
|
|
|
flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
|
|
pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
|
|
if (pmd_dirty(pmdval))
|
|
set_page_dirty(page);
|
|
entry = make_migration_entry(page, pmd_write(pmdval));
|
|
pmdswp = swp_entry_to_pmd(entry);
|
|
if (pmd_soft_dirty(pmdval))
|
|
pmdswp = pmd_swp_mksoft_dirty(pmdswp);
|
|
set_pmd_at(mm, address, pvmw->pmd, pmdswp);
|
|
page_remove_rmap(page, true);
|
|
put_page(page);
|
|
}
|
|
|
|
void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
|
|
{
|
|
struct vm_area_struct *vma = pvmw->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long address = pvmw->address;
|
|
unsigned long mmun_start = address & HPAGE_PMD_MASK;
|
|
pmd_t pmde;
|
|
swp_entry_t entry;
|
|
|
|
if (!(pvmw->pmd && !pvmw->pte))
|
|
return;
|
|
|
|
entry = pmd_to_swp_entry(*pvmw->pmd);
|
|
get_page(new);
|
|
pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
|
|
if (pmd_swp_soft_dirty(*pvmw->pmd))
|
|
pmde = pmd_mksoft_dirty(pmde);
|
|
if (is_write_migration_entry(entry))
|
|
pmde = maybe_pmd_mkwrite(pmde, vma);
|
|
|
|
flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
|
|
if (PageAnon(new))
|
|
page_add_anon_rmap(new, vma, mmun_start, true);
|
|
else
|
|
page_add_file_rmap(new, true);
|
|
set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
|
|
if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
|
|
mlock_vma_page(new);
|
|
update_mmu_cache_pmd(vma, address, pvmw->pmd);
|
|
}
|
|
#endif
|