[PATCHv2 03/14] mm/shmem: Zero out unused vma fields in shmem_pseudo_vma_init()

From: Kirill A. Shutemov
Date: Wed Mar 28 2018 - 12:59:17 EST


shmem/tmpfs uses pseudo vma to allocate page with correct NUMA policy.

The pseudo vma doesn't have vm_page_prot set. We are going to encode
encryption KeyID in vm_page_prot. Having garbage there causes problems.

Zero out all unused fields in the pseudo vma.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/shmem.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index b85919243399..387b89d9e17a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1404,10 +1404,9 @@ static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
struct shmem_inode_info *info, pgoff_t index)
{
/* Create a pseudo vma that just contains the policy */
- vma->vm_start = 0;
+ memset(vma, 0, sizeof(*vma));
/* Bias interleave by inode number to distribute better across nodes */
vma->vm_pgoff = index + info->vfs_inode.i_ino;
- vma->vm_ops = NULL;
vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
}

--
2.16.2