From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Subject: fs/userfaultfd.c: wp: clear VM_UFFD_MISSING or VM_UFFD_WP during userfaultfd_register() If the registration is repeated without VM_UFFD_MISSING or VM_UFFD_WP they need to be cleared. Currently setting UFFDIO_REGISTER_MODE_WP returns -EINVAL, so this patch is a noop until the UFFDIO_REGISTER_MODE_WP support is applied. Link: http://lkml.kernel.org/r/20191004232834.GP13922@xxxxxxxxxx Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Reported-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> Reviewed-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/userfaultfd.c~uffd-wp-clear-vm_uffd_missing-or-vm_uffd_wp-during-userfaultfd_register +++ a/fs/userfaultfd.c @@ -1460,7 +1460,8 @@ static int userfaultfd_register(struct u start = vma->vm_start; vma_end = min(end, vma->vm_end); - new_flags = (vma->vm_flags & ~vm_flags) | vm_flags; + new_flags = (vma->vm_flags & + ~(VM_UFFD_MISSING|VM_UFFD_WP)) | vm_flags; prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), _
