From 41eee5319f475b568536caa3e769861f6cfd0b7e Mon Sep 17 00:00:00 2001
From: Laura Abbott <labbott@redhat.com>
Date: Tue, 13 Mar 2018 20:46:11 -0700
Subject: [PATCH] Fix for boot hang on arm64 (rhbz 1554954)

---
 kernel.spec                                   |  3 +
 ...oc-fix-boot-hang-in-memmap_init_zone.patch | 58 +++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 mm-page_alloc-fix-boot-hang-in-memmap_init_zone.patch

diff --git a/kernel.spec b/kernel.spec
index 41c124601..9a6144ede 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -622,6 +622,9 @@ Patch502: input-rmi4-remove-the-need-for-artifical-IRQ.patch
 # rhbz 1509461
 Patch503: v3-2-2-Input-synaptics---Lenovo-X1-Carbon-5-should-use-SMBUS-RMI.patch
 
+# rhbz 1554954
+Patch504: mm-page_alloc-fix-boot-hang-in-memmap_init_zone.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
diff --git a/mm-page_alloc-fix-boot-hang-in-memmap_init_zone.patch b/mm-page_alloc-fix-boot-hang-in-memmap_init_zone.patch
new file mode 100644
index 000000000..466493db3
--- /dev/null
+++ b/mm-page_alloc-fix-boot-hang-in-memmap_init_zone.patch
@@ -0,0 +1,58 @@
+From patchwork Tue Mar 13 22:42:40 2018
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: mm/page_alloc: fix boot hang in memmap_init_zone
+From: Daniel Vacek <neelx@redhat.com>
+X-Patchwork-Id: 10281093
+Message-Id: <20180313224240.25295-1-neelx@redhat.com>
+To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
+Cc: Sudeep Holla <sudeep.holla@arm.com>,
+ Naresh Kamboju <naresh.kamboju@linaro.org>,
+ Daniel Vacek <neelx@redhat.com>, Andrew Morton <akpm@linux-foundation.org>,
+ Mel Gorman <mgorman@techsingularity.net>, Michal Hocko <mhocko@suse.com>,
+ Paul Burton <paul.burton@imgtec.com>,
+ Pavel Tatashin <pasha.tatashin@oracle.com>,
+ Vlastimil Babka <vbabka@suse.cz>, stable@vger.kernel.org
+Date: Tue, 13 Mar 2018 23:42:40 +0100
+
+On some architectures (reported on arm64) commit 864b75f9d6b01 ("mm/page_alloc: fix memmap_init_zone pageblock alignment")
+causes a boot hang. This patch fixes the hang making sure the alignment
+never steps back.
+
+Link: http://lkml.kernel.org/r/0485727b2e82da7efbce5f6ba42524b429d0391a.1520011945.git.neelx@redhat.com
+Fixes: 864b75f9d6b01 ("mm/page_alloc: fix memmap_init_zone pageblock alignment")
+Signed-off-by: Daniel Vacek <neelx@redhat.com>
+Tested-by: Sudeep Holla <sudeep.holla@arm.com>
+Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
+Cc: Andrew Morton <akpm@linux-foundation.org>
+Cc: Mel Gorman <mgorman@techsingularity.net>
+Cc: Michal Hocko <mhocko@suse.com>
+Cc: Paul Burton <paul.burton@imgtec.com>
+Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
+Cc: Vlastimil Babka <vbabka@suse.cz>
+Cc: <stable@vger.kernel.org>
+---
+ mm/page_alloc.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/mm/page_alloc.c b/mm/page_alloc.c
+index 3d974cb2a1a1..e033a6895c6f 100644
+--- a/mm/page_alloc.c
++++ b/mm/page_alloc.c
+@@ -5364,9 +5364,14 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
+ 			 * is not. move_freepages_block() can shift ahead of
+ 			 * the valid region but still depends on correct page
+ 			 * metadata.
++			 * Also make sure we never step back.
+ 			 */
+-			pfn = (memblock_next_valid_pfn(pfn, end_pfn) &
++			unsigned long next_pfn;
++
++			next_pfn = (memblock_next_valid_pfn(pfn, end_pfn) &
+ 					~(pageblock_nr_pages-1)) - 1;
++			if (next_pfn > pfn)
++				pfn = next_pfn;
+ #endif
+ 			continue;
+ 		}