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Commit f66055ab authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

thp: verify pmd_trans_huge isn't leaking 



pte_trans_huge must not leak in certain vmas like the mmio special pfn or
filebacked mappings.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05759d38

mm/memory.c

+6 −1
Original line number Diff line number Diff line
@@ -1451,6 +1451,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
			pmd = pmd_offset(pud, pg);

			if (pmd_none(*pmd))

				return i ? : -EFAULT;

			VM_BUG_ON(pmd_trans_huge(*pmd));

			pte = pte_offset_map(pmd, pg);

			if (pte_none(*pte)) {

				pte_unmap(pte);
@@ -1675,9 +1676,11 @@ pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 
	pud_t * pud = pud_alloc(mm, pgd, addr);

	if (pud) {

		pmd_t * pmd = pmd_alloc(mm, pud, addr);

		if (pmd)

		if (pmd) {

			VM_BUG_ON(pmd_trans_huge(*pmd));

			return pte_alloc_map_lock(mm, pmd, addr, ptl);

		}

	}

	return NULL;

}
@@ -1895,6 +1898,7 @@ static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 
	pmd = pmd_alloc(mm, pud, addr);

	if (!pmd)

		return -ENOMEM;

	VM_BUG_ON(pmd_trans_huge(*pmd));

	do {

		next = pmd_addr_end(addr, end);

		if (remap_pte_range(mm, pmd, addr, next,
@@ -3471,6 +3475,7 @@ static int __follow_pte(struct mm_struct *mm, unsigned long address, 
		goto out;



	pmd = pmd_offset(pud, address);

	VM_BUG_ON(pmd_trans_huge(*pmd));

	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))

		goto out;