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![Hugh Dickins](/assets/img/avatar_default.png)
Patch series "mm/thp: fix THP splitting unmap BUGs and related", v10.
Here is v2 batch of long-standing THP bug fixes that I had not got
around to sending before, but prompted now by Wang Yugui's report
https://lore.kernel.org/linux-mm/20210412180659.B9E3.409509F4@e16-tech.com/
Wang Yugui has tested a rollup of these fixes applied to 5.10.39, and
they have done no harm, but have *not* fixed that issue: something more
is needed and I have no idea of what.
This patch (of 7):
Stressing huge tmpfs page migration racing hole punch often crashed on
the VM_BUG_ON(!pmd_present) in pmdp_huge_clear_flush(), with DEBUG_VM=y
kernel; or shortly afterwards, on a bad dereference in
__split_huge_pmd_locked() when DEBUG_VM=n. They forgot to allow for pmd
migration entries in the non-anonymous case.
Full disclosure: those particular experiments were on a kernel with more
relaxed mmap_lock and i_mmap_rwsem locking, and were not repeated on the
vanilla kernel: it is conceivable that stricter locking happens to avoid
those cases, or makes them less likely; but __split_huge_pmd_locked()
already allowed for pmd migration entries when handling anonymous THPs,
so this commit brings the shmem and file THP handling into line.
And while there: use old_pmd rather than _pmd, as in the following
blocks; and make it clearer to the eye that the !vma_is_anonymous()
block is self-contained, making an early return after accounting for
unmapping.
Link: https://lkml.kernel.org/r/af88612-1473-2eaa-903-8d1a448b26@google.com
Link: https://lkml.kernel.org/r/dd221a99-efb3-cd1d-6256-7e646af29314@google.com
Fixes: e71769ae52
("mm: enable thp migration for shmem thp")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jue Wang <juew@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
222 lines
5.6 KiB
C
222 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* mm/pgtable-generic.c
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*
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* Generic pgtable methods declared in linux/pgtable.h
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*
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* Copyright (C) 2010 Linus Torvalds
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*/
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#include <linux/pagemap.h>
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#include <linux/hugetlb.h>
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#include <linux/pgtable.h>
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#include <asm/tlb.h>
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/*
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* If a p?d_bad entry is found while walking page tables, report
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* the error, before resetting entry to p?d_none. Usually (but
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* very seldom) called out from the p?d_none_or_clear_bad macros.
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*/
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void pgd_clear_bad(pgd_t *pgd)
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{
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pgd_ERROR(*pgd);
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pgd_clear(pgd);
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}
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#ifndef __PAGETABLE_P4D_FOLDED
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void p4d_clear_bad(p4d_t *p4d)
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{
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p4d_ERROR(*p4d);
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p4d_clear(p4d);
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}
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#endif
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#ifndef __PAGETABLE_PUD_FOLDED
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void pud_clear_bad(pud_t *pud)
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{
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pud_ERROR(*pud);
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pud_clear(pud);
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}
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#endif
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/*
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* Note that the pmd variant below can't be stub'ed out just as for p4d/pud
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* above. pmd folding is special and typically pmd_* macros refer to upper
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* level even when folded
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*/
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void pmd_clear_bad(pmd_t *pmd)
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{
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pmd_ERROR(*pmd);
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pmd_clear(pmd);
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}
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#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
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/*
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* Only sets the access flags (dirty, accessed), as well as write
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* permission. Furthermore, we know it always gets set to a "more
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* permissive" setting, which allows most architectures to optimize
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* this. We return whether the PTE actually changed, which in turn
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* instructs the caller to do things like update__mmu_cache. This
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* used to be done in the caller, but sparc needs minor faults to
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* force that call on sun4c so we changed this macro slightly
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*/
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int ptep_set_access_flags(struct vm_area_struct *vma,
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unsigned long address, pte_t *ptep,
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pte_t entry, int dirty)
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{
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int changed = !pte_same(*ptep, entry);
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if (changed) {
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set_pte_at(vma->vm_mm, address, ptep, entry);
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flush_tlb_fix_spurious_fault(vma, address);
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}
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return changed;
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}
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#endif
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#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
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int ptep_clear_flush_young(struct vm_area_struct *vma,
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unsigned long address, pte_t *ptep)
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{
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int young;
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young = ptep_test_and_clear_young(vma, address, ptep);
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if (young)
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flush_tlb_page(vma, address);
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return young;
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}
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#endif
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#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
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pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
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pte_t *ptep)
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{
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struct mm_struct *mm = (vma)->vm_mm;
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pte_t pte;
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pte = ptep_get_and_clear(mm, address, ptep);
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if (pte_accessible(mm, pte))
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flush_tlb_page(vma, address);
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return pte;
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}
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#endif
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
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int pmdp_set_access_flags(struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmdp,
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pmd_t entry, int dirty)
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{
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int changed = !pmd_same(*pmdp, entry);
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VM_BUG_ON(address & ~HPAGE_PMD_MASK);
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if (changed) {
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set_pmd_at(vma->vm_mm, address, pmdp, entry);
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flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
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}
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return changed;
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}
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#endif
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#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
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int pmdp_clear_flush_young(struct vm_area_struct *vma,
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unsigned long address, pmd_t *pmdp)
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{
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int young;
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VM_BUG_ON(address & ~HPAGE_PMD_MASK);
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young = pmdp_test_and_clear_young(vma, address, pmdp);
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if (young)
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flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
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return young;
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}
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#endif
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#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
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pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
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pmd_t *pmdp)
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{
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pmd_t pmd;
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VM_BUG_ON(address & ~HPAGE_PMD_MASK);
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VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
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!pmd_devmap(*pmdp));
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pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
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flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
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return pmd;
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}
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#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
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pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
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pud_t *pudp)
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{
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pud_t pud;
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VM_BUG_ON(address & ~HPAGE_PUD_MASK);
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VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
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pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
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flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
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return pud;
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}
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#endif
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#endif
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#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
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void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
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pgtable_t pgtable)
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{
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assert_spin_locked(pmd_lockptr(mm, pmdp));
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/* FIFO */
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if (!pmd_huge_pte(mm, pmdp))
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INIT_LIST_HEAD(&pgtable->lru);
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else
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list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
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pmd_huge_pte(mm, pmdp) = pgtable;
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}
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#endif
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#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
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/* no "address" argument so destroys page coloring of some arch */
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pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
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{
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pgtable_t pgtable;
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assert_spin_locked(pmd_lockptr(mm, pmdp));
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/* FIFO */
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pgtable = pmd_huge_pte(mm, pmdp);
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pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
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struct page, lru);
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if (pmd_huge_pte(mm, pmdp))
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list_del(&pgtable->lru);
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return pgtable;
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}
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#endif
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#ifndef __HAVE_ARCH_PMDP_INVALIDATE
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pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
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pmd_t *pmdp)
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{
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pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp));
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flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
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return old;
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}
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#endif
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#ifndef pmdp_collapse_flush
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pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
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pmd_t *pmdp)
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{
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/*
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* pmd and hugepage pte format are same. So we could
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* use the same function.
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*/
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pmd_t pmd;
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VM_BUG_ON(address & ~HPAGE_PMD_MASK);
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VM_BUG_ON(pmd_trans_huge(*pmdp));
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pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
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/* collapse entails shooting down ptes not pmd */
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flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
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return pmd;
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}
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#endif
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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