Re: [PATCH] dax: Change return type to vm_fault_t

[Dan Williams <dan.j.williams@intel.com>]

On Sat, Apr 14, 2018 at 8:50 AM, Souptick Joarder <jrdr.linux@gmail.com> wrote:
> Use new return type vm_fault_t for fault and
> huge_fault handler.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
> ---
>  drivers/dax/device.c | 26 +++++++++++---------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index 2137dbc..a122701 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -243,11 +243,11 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
>         return -1;
>  }
>
> -static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
> +static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
> +                               struct vm_fault *vmf)
>  {
>         struct device *dev = &dev_dax->dev;
>         struct dax_region *dax_region;
> -       int rc = VM_FAULT_SIGBUS;
>         phys_addr_t phys;
>         pfn_t pfn;
>         unsigned int fault_size = PAGE_SIZE;
> @@ -274,17 +274,11 @@ static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
>
>         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
>
> -       rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
> -
> -       if (rc == -ENOMEM)
> -               return VM_FAULT_OOM;
> -       if (rc < 0 && rc != -EBUSY)
> -               return VM_FAULT_SIGBUS;
> -
> -       return VM_FAULT_NOPAGE;
> +       return vmf_insert_mixed(vmf->vma, vmf->address, pfn);

Ugh, so this change to vmf_insert_mixed() went upstream without fixing
the users? This changelog is now misleading as it does not mention
that is now an urgent standalone fix. On first read I assumed this was
part of a wider effort for 4.18.

Grumble, we'll get this applied with a 'Fixes: 1c8f422059ae ("mm:
change return type to vm_fault_t")' tag.