From: Thomas Hellstrom thellstrom@vmware.com
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 thellstrom@vmware.com --- 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 0157d293935f..d370ce2932a1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2822,6 +2822,23 @@ 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 41a0fbddc96b..f8d24fc3f4df 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1789,7 +1789,7 @@ 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); @@ -2053,7 +2053,7 @@ 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 { @@ -2162,7 +2162,7 @@ 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))