[PATCH v2] powerpc/mm/nvdimm: Add an informative message if we fail to allocate altmap block

[Oliver O'Halloran]

On Tue, Jul 2, 2019 at 12:33 AM Aneesh Kumar K.V
<aneesh.kumar at linux.ibm.com> wrote:
>
> Allocation from altmap area can fail based on vmemmap page size used. Add kernel
> info message to indicate the failure. That allows the user to identify whether they
> are really using persistent memory reserved space for per-page metadata.
>
> The message looks like:
> [  136.587212] altmap block allocation failed, falling back to system memory
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>  arch/powerpc/mm/init_64.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index a4e17a979e45..f3b64f49082b 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -194,8 +194,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>                  * fail due to alignment issues when using 16MB hugepages, so
>                  * fall back to system memory if the altmap allocation fail.
>                  */
> -               if (altmap)
> +               if (altmap) {
>                         p = altmap_alloc_block_buf(page_size, altmap);
> +                       if (!p)
> +                               pr_debug("altmap block allocation failed, " \
> +                                       "falling back to system memory");
> +               }
>                 if (!p)
>                         p = vmemmap_alloc_block_buf(page_size, node);
>                 if (!p)
> --
> 2.21.0
>

I'll let mpe decide if he cares about the split line thing :)

Reviewed-by: Oliver O'Halloran <oohall at gmail.com>