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

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@linux.ibm.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 45b02fa11cd81c4c4e1cb8297313e4587a9a4e0d..b219160a5b1a4f14b67dd65f349b37d958f03bf5 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -199,8 +199,11 @@ 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)