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Subject[PATCH 4.15 005/122] powerpc/pseries: Enable RAS hotplug events later
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

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) {

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