On x86_32, while onlining highmem sections, the func default_zone_for_pfn()
defaults target zone to ZONE_NORMAL (movable_node_enabled = 0). Onlining of
pages is successful, and these highmem pages are moved into zone_normal.
As a consequence, these pages are treated as low mem, and page addresses
are calculated using lowmem_page_address() which effectively overflows the
32 bit virtual addresses, leading to kernel panics and system becomes
unusable.
Change default_kernel_zone_for_pfn() to intersect highmem pfn range, and
calculate the default zone accordingly.
Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@xxxxxxxxx>
---
mm/memory_hotplug.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c4d5c45..30f101a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -725,8 +725,13 @@ static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn
{
struct pglist_data *pgdat = NODE_DATA(nid);
int zid;
+ int nr_zones = ZONE_NORMAL;
- for (zid = 0; zid <= ZONE_NORMAL; zid++) {
+#ifdef CONFIG_HIGHMEM
+ nr_zones = ZONE_HIGHMEM;
+#endif
+
+ for (zid = 0; zid <= nr_zones; zid++) {
struct zone *zone = &pgdat->node_zones[zid];
if (zone_intersects(zone, start_pfn, nr_pages))
--
2.7.4
