--- /dev/null
+From c9dccf1d074a67d36c510845f663980d69e3409b Mon Sep 17 00:00:00 2001
+From: Sam Bobroff <sam.bobroff@au1.ibm.com>
+Date: Mon, 12 Feb 2018 11:19:29 +1100
+Subject: powerpc/pseries: Enable RAS hotplug events later
+
+From: Sam Bobroff <sam.bobroff@au1.ibm.com>
+
+commit c9dccf1d074a67d36c510845f663980d69e3409b upstream.
+
+Currently if the kernel receives a memory hot-unplug event early
+enough, it may get stuck in an infinite loop in
+dissolve_free_huge_pages(). This appears as a stall just after:
+
+ pseries-hotplug-mem: Attempting to hot-remove XX LMB(s) at YYYYYYYY
+
+It appears to be caused by "minimum_order" being uninitialized, due to
+init_ras_IRQ() executing before hugetlb_init().
+
+To correct this, extract the part of init_ras_IRQ() that enables
+hotplug event processing and place it in the machine_late_initcall
+phase, which is guaranteed to be after hugetlb_init() is called.
+
+Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
+Acked-by: Balbir Singh <bsingharora@gmail.com>
+[mpe: Reorder the functions to make the diff readable]
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/platforms/pseries/ras.c | 31 ++++++++++++++++++++++---------
+ 1 file changed, 22 insertions(+), 9 deletions(-)
+
+--- a/arch/powerpc/platforms/pseries/ras.c
++++ b/arch/powerpc/platforms/pseries/ras.c
+@@ -49,6 +49,28 @@ static irqreturn_t ras_error_interrupt(i
+
+
+ /*
++ * Enable the hotplug interrupt late because processing them may touch other
++ * devices or systems (e.g. hugepages) that have not been initialized at the
++ * subsys stage.
++ */
++int __init init_ras_hotplug_IRQ(void)
++{
++ struct device_node *np;
++
++ /* Hotplug Events */
++ np = of_find_node_by_path("/event-sources/hot-plug-events");
++ if (np != NULL) {
++ if (dlpar_workqueue_init() == 0)
++ request_event_sources_irqs(np, ras_hotplug_interrupt,
++ "RAS_HOTPLUG");
++ of_node_put(np);
++ }
++
++ return 0;
++}
++machine_late_initcall(pseries, init_ras_hotplug_IRQ);
++
++/*
+ * Initialize handlers for the set of interrupts caused by hardware errors
+ * and power system events.
+ */
+@@ -66,15 +88,6 @@ static int __init init_ras_IRQ(void)
+ of_node_put(np);
+ }
+
+- /* Hotplug Events */
+- np = of_find_node_by_path("/event-sources/hot-plug-events");
+- if (np != NULL) {
+- if (dlpar_workqueue_init() == 0)
+- request_event_sources_irqs(np, ras_hotplug_interrupt,
+- "RAS_HOTPLUG");
+- of_node_put(np);
+- }
+-
+ /* EPOW Events */
+ np = of_find_node_by_path("/event-sources/epow-events");
+ if (np != NULL) {