From 2484ca9b6a20451debb789d0a89af6f15de99826 Mon Sep 17 00:00:00 2001 From: "Thomas Hellstrom (VMware)" Date: Tue, 24 Mar 2020 18:47:17 +0100 Subject: mm: Introduce vma_is_special_huge MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: Michal Hocko Cc: "Matthew Wilcox (Oracle)" Cc: "Kirill A. Shutemov" Cc: Ralph Campbell Cc: "Jérôme Glisse" Cc: "Christian König" Cc: Dan Williams Signed-off-by: Thomas Hellstrom (VMware) Acked-by: Christian König Acked-by: Andrew Morton --- include/linux/mm.h | 17 +++++++++++++++++ mm/huge_memory.c | 6 +++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index c54fb96cb1e6..bdd79a72bb42 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2867,6 +2867,23 @@ extern long copy_huge_page_from_user(struct page *dst_page, const void __user *usr_src, unsigned int pages_per_huge_page, bool allow_pagefault); + +/** + * vma_is_special_huge - Are transhuge page-table entries considered special? + * @vma: Pointer to the struct vm_area_struct to consider + * + * Whether transhuge page-table entries are considered "special" following + * the definition in vm_normal_page(). + * + * Return: true if transhuge page-table entries should be considered special, + * false otherwise. + */ +static inline bool vma_is_special_huge(const struct vm_area_struct *vma) +{ + return vma_is_dax(vma) || (vma->vm_file && + (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))); +} + #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #ifdef CONFIG_DEBUG_PAGEALLOC diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 24ad53b4dfc0..19c8d462ab08 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1802,7 +1802,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, tlb->fullmm); tlb_remove_pmd_tlb_entry(tlb, pmd, addr); - if (vma_is_dax(vma)) { + if (vma_is_special_huge(vma)) { if (arch_needs_pgtable_deposit()) zap_deposited_table(tlb->mm, pmd); spin_unlock(ptl); @@ -2066,7 +2066,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, */ pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); tlb_remove_pud_tlb_entry(tlb, pud, addr); - if (vma_is_dax(vma)) { + if (vma_is_special_huge(vma)) { spin_unlock(ptl); /* No zero page support yet */ } else { @@ -2175,7 +2175,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, */ if (arch_needs_pgtable_deposit()) zap_deposited_table(mm, pmd); - if (vma_is_dax(vma)) + if (vma_is_special_huge(vma)) return; page = pmd_page(_pmd); if (!PageDirty(page) && pmd_dirty(_pmd)) -- cgit v1.2.3