> On Dec 10, 2018, at 10:34 PM, Peter Xu <peterx@xxxxxxxxxx> wrote:
>
> ---
> fs/userfaultfd.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index cd58939dc977..4567b5b6fd32 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -736,10 +736,18 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma,
> struct userfaultfd_ctx *ctx;
>
> ctx = vma->vm_userfaultfd_ctx.ctx;
> - if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
> +
> + if (!ctx)
> + return;
> +
> + if (ctx->features & UFFD_FEATURE_EVENT_REMAP) {
> vm_ctx->ctx = ctx;
> userfaultfd_ctx_get(ctx);
> WRITE_ONCE(ctx->mmap_changing, true);
> + } else {
> + /* Drop uffd context if remap feature not enabled */
> + vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
> + vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
> }
> }
>
> --
> 2.17.1
>
Looks good.
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
