diff options
| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2015-05-11 11:58:29 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-05-12 11:04:29 +1000 |
| commit | 7b868e81be38d5ad4f4aa4be819a5fa543cc5ee8 (patch) | |
| tree | 42fddf3b104664e76634117569eeaafc733731a7 /arch/powerpc | |
| parent | 13bd817bb88499ce1dc1dfdaffcde17fa492aca5 (diff) | |
powerpc/mm: Return NULL for not present hugetlb page
We need to check whether pte is present in follow_huge_addr() and
properly return NULL if mapping is not present. Also use READ_ONCE
when dereferencing pte_t address.
Without this patch, we may wrongly return a zero pfn page in
follow_huge_addr().
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/mm/hugetlbpage.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 0ce968b00b7c..3385e3d0506e 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -689,27 +689,34 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb, struct page * follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) { - pte_t *ptep; - struct page *page; + pte_t *ptep, pte; unsigned shift; unsigned long mask, flags; + struct page *page = ERR_PTR(-EINVAL); + + local_irq_save(flags); + ptep = find_linux_pte_or_hugepte(mm->pgd, address, &shift); + if (!ptep) + goto no_page; + pte = READ_ONCE(*ptep); /* + * Verify it is a huge page else bail. * Transparent hugepages are handled by generic code. We can skip them * here. */ - local_irq_save(flags); - ptep = find_linux_pte_or_hugepte(mm->pgd, address, &shift); + if (!shift || pmd_trans_huge(__pmd(pte_val(pte)))) + goto no_page; - /* Verify it is a huge page else bail. */ - if (!ptep || !shift || pmd_trans_huge(*(pmd_t *)ptep)) { - local_irq_restore(flags); - return ERR_PTR(-EINVAL); + if (!pte_present(pte)) { + page = NULL; + goto no_page; } mask = (1UL << shift) - 1; - page = pte_page(*ptep); + page = pte_page(pte); if (page) page += (address & mask) / PAGE_SIZE; +no_page: local_irq_restore(flags); return page; } |