Re: [PATCH 07/25] memremap: validate the pagemap type passed to devm_memremap_pages

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

On Mon, Jun 17, 2019 at 5:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Most pgmap types are only supported when certain config options are
> enabled.  Check for a type that is valid for the current configuration
> before setting up the pagemap.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  kernel/memremap.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index 6e1970719dc2..6a2dd31a6250 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -157,6 +157,33 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
>         pgprot_t pgprot = PAGE_KERNEL;
>         int error, nid, is_ram;
>
> +       switch (pgmap->type) {
> +       case MEMORY_DEVICE_PRIVATE:
> +               if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
> +                       WARN(1, "Device private memory not supported\n");
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               break;
> +       case MEMORY_DEVICE_PUBLIC:
> +               if (!IS_ENABLED(CONFIG_DEVICE_PUBLIC)) {
> +                       WARN(1, "Device public memory not supported\n");
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               break;
> +       case MEMORY_DEVICE_FS_DAX:
> +               if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
> +                   IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
> +                       WARN(1, "File system DAX not supported\n");
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               break;
> +       case MEMORY_DEVICE_PCI_P2PDMA:

Need a lead in patch that introduces MEMORY_DEVICE_DEVDAX, otherwise:

 Invalid pgmap type 0
 WARNING: CPU: 6 PID: 1316 at kernel/memremap.c:183
devm_memremap_pages+0x1d8/0x700
 [..]
 RIP: 0010:devm_memremap_pages+0x1d8/0x700
 [..]
 Call Trace:
  dev_dax_probe+0xc7/0x1e0 [device_dax]
  really_probe+0xef/0x390
  driver_probe_device+0xb4/0x100
  device_driver_attach+0x4f/0x60