Commit 2484ca9b authored by Thomas Hellstrom (VMware)'s avatar Thomas Hellstrom (VMware)
Browse files

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: default avatarThomas Hellstrom (VMware) <thomas_os@shipmail.org>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f05a3849

include/linux/mm.h

+17 −0
Original line number Original line Diff line number Diff line
@@ -2867,6 +2867,23 @@ extern long copy_huge_page_from_user(struct page *dst_page, 
				const void __user *usr_src,

				const void __user *usr_src,

				unsigned int pages_per_huge_page,

				unsigned int pages_per_huge_page,

				bool allow_pagefault);

				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 */

#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */





#ifdef CONFIG_DEBUG_PAGEALLOC

#ifdef CONFIG_DEBUG_PAGEALLOC

mm/huge_memory.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -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,

	orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,

			tlb->fullmm);

			tlb->fullmm);

	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);

	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);

	if (vma_is_dax(vma)) {

	if (vma_is_special_huge(vma)) {

		if (arch_needs_pgtable_deposit())

		if (arch_needs_pgtable_deposit())

			zap_deposited_table(tlb->mm, pmd);

			zap_deposited_table(tlb->mm, pmd);

		spin_unlock(ptl);

		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);

	pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);

	tlb_remove_pud_tlb_entry(tlb, pud, addr);

	tlb_remove_pud_tlb_entry(tlb, pud, addr);

	if (vma_is_dax(vma)) {

	if (vma_is_special_huge(vma)) {

		spin_unlock(ptl);

		spin_unlock(ptl);

		/* No zero page support yet */

		/* No zero page support yet */

	} else {

	} else {
@@ -2175,7 +2175,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 
		 */

		 */

		if (arch_needs_pgtable_deposit())

		if (arch_needs_pgtable_deposit())

			zap_deposited_table(mm, pmd);

			zap_deposited_table(mm, pmd);

		if (vma_is_dax(vma))

		if (vma_is_special_huge(vma))

			return;

			return;

		page = pmd_page(_pmd);

		page = pmd_page(_pmd);

		if (!PageDirty(page) && pmd_dirty(_pmd))

		if (!PageDirty(page) && pmd_dirty(_pmd))

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