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mm: Introduce vma_is_special_huge
For VM_PFNMAP and VM_MIXEDMAP vmas that want to support transhuge pages and -page table entries, introduce vma_is_special_huge() that takes the same codepaths as vma_is_dax(). The use of "special" follows the definition in memory.c, vm_normal_page(): "Special" mappings do not wish to be associated with a "struct page" (either it doesn't exist, or it exists but they don't want to touch it) For PAGE_SIZE pages, "special" is determined per page table entry to be able to deal with COW pages. But since we don't have huge COW pages, we can classify a vma as either "special huge" or "normal huge". Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: "Christian König" <christian.koenig@amd.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Thomas Hellstrom (VMware) <thomas_os@shipmail.org> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Andrew Morton <akpm@linux-foundation.org>
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2 changed files with 20 additions and 3 deletions
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@ -2867,6 +2867,23 @@ extern long copy_huge_page_from_user(struct page *dst_page,
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const void __user *usr_src,
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unsigned int pages_per_huge_page,
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bool allow_pagefault);
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/**
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* vma_is_special_huge - Are transhuge page-table entries considered special?
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* @vma: Pointer to the struct vm_area_struct to consider
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*
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* Whether transhuge page-table entries are considered "special" following
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* the definition in vm_normal_page().
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*
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* Return: true if transhuge page-table entries should be considered special,
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* false otherwise.
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*/
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static inline bool vma_is_special_huge(const struct vm_area_struct *vma)
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{
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return vma_is_dax(vma) || (vma->vm_file &&
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(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)));
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}
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
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#ifdef CONFIG_DEBUG_PAGEALLOC
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@ -1802,7 +1802,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
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orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
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tlb->fullmm);
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tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
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if (vma_is_dax(vma)) {
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if (vma_is_special_huge(vma)) {
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if (arch_needs_pgtable_deposit())
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zap_deposited_table(tlb->mm, pmd);
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spin_unlock(ptl);
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@ -2066,7 +2066,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
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*/
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pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
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tlb_remove_pud_tlb_entry(tlb, pud, addr);
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if (vma_is_dax(vma)) {
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if (vma_is_special_huge(vma)) {
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spin_unlock(ptl);
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/* No zero page support yet */
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} else {
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@ -2175,7 +2175,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
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*/
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if (arch_needs_pgtable_deposit())
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zap_deposited_table(mm, pmd);
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if (vma_is_dax(vma))
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if (vma_is_special_huge(vma))
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return;
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page = pmd_page(_pmd);
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if (!PageDirty(page) && pmd_dirty(_pmd))
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