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 <[email protected]> --- 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
