Re: [PATCH 2/2] drivers/dax: Changing RC value

Andrew Morton
2017-04-11T20:58:29Z

On Tue, 11 Apr 2017 10:56:45 +0530 Pushkar Jambhlekar <pushkar.iit@gmail.com> wrote:

> Changing rc value from VM_FAULT_FALLBACK to VM_FAULT_SIGBUS for an unknown / unsupported fault size.
>
> ...
>
> --- a/drivers/dax/dax.c
> +++ b/drivers/dax/dax.c
> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
> rc = __dax_dev_pud_fault(dax_dev, vmf);
> break;
> default:
> - rc = VM_FAULT_FALLBACK;
> + rc = VM_FAULT_SIGBUS;
> }
> rcu_read_unlock();

The change seems to make sense but more info would be helpful. What
is wrong with the current code? ie, what goes wrong if we return
VM_FAULT_FALLBACK here?