summaryrefslogtreecommitdiff
path: root/arch/powerpc/mm
diff options
context:
space:
mode:
authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2015-05-11 09:28:29 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2015-05-12 04:04:29 +0300
commit7b868e81be38d5ad4f4aa4be819a5fa543cc5ee8 (patch)
tree42fddf3b104664e76634117569eeaafc733731a7 /arch/powerpc/mm
parent13bd817bb88499ce1dc1dfdaffcde17fa492aca5 (diff)
downloadlinux-7b868e81be38d5ad4f4aa4be819a5fa543cc5ee8.tar.xz
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/mm')
-rw-r--r--arch/powerpc/mm/hugetlbpage.c25
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;
}