From c0b1b23b9c87569d5f90d06e86f26b31b544fa1e Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Date: Mon, 1 Jul 2019 20:03:38 +0530
Subject: [PATCH] powerpc/mm/nvdimm: Add an informative message if we fail to
 allocate altmap block

References: bsc#1142685 LTC#179509 FATE#327775
Patch-mainline: v5.3-rc1
Git-commit: c0b1b23b9c87569d5f90d06e86f26b31b544fa1e

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>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/mm/init_64.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 45b02fa11cd8..b219160a5b1a 100644
--- 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)
-- 
2.22.0