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Commit cd7548ab authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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thp: mprotect: transparent huge page support 



Natively handle huge pmds when changing page tables on behalf of
mprotect().

I left out update_mmu_cache() because we do not need it on x86 anyway but
more importantly the interface works on ptes, not pmds.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b36f5b07

include/linux/huge_mm.h

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ extern int zap_huge_pmd(struct mmu_gather *tlb, 
extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

			unsigned long addr, unsigned long end,

			unsigned char *vec);

extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

			unsigned long addr, pgprot_t newprot);



enum transparent_hugepage_flag {

	TRANSPARENT_HUGEPAGE_FLAG,

mm/huge_memory.c

+27 −0
Original line number Diff line number Diff line
@@ -948,6 +948,33 @@ int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 
	return ret;

}



int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

		unsigned long addr, pgprot_t newprot)

{

	struct mm_struct *mm = vma->vm_mm;

	int ret = 0;



	spin_lock(&mm->page_table_lock);

	if (likely(pmd_trans_huge(*pmd))) {

		if (unlikely(pmd_trans_splitting(*pmd))) {

			spin_unlock(&mm->page_table_lock);

			wait_split_huge_page(vma->anon_vma, pmd);

		} else {

			pmd_t entry;



			entry = pmdp_get_and_clear(mm, addr, pmd);

			entry = pmd_modify(entry, newprot);

			set_pmd_at(mm, addr, pmd, entry);

			spin_unlock(&vma->vm_mm->page_table_lock);

			flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);

			ret = 1;

		}

	} else

		spin_unlock(&vma->vm_mm->page_table_lock);



	return ret;

}



pmd_t *page_check_address_pmd(struct page *page,

			      struct mm_struct *mm,

			      unsigned long address,

mm/mprotect.c

+7 −1
Original line number Diff line number Diff line
@@ -88,7 +88,13 @@ static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud, 
	pmd = pmd_offset(pud, addr);

	do {

		next = pmd_addr_end(addr, end);

		if (pmd_trans_huge(*pmd)) {

			if (next - addr != HPAGE_PMD_SIZE)

				split_huge_page_pmd(vma->vm_mm, pmd);

			else if (change_huge_pmd(vma, pmd, addr, newprot))

				continue;

			/* fall through */

		}

		if (pmd_none_or_clear_bad(pmd))

			continue;

		change_pte_range(vma->vm_mm, pmd, addr, next, newprot,