On Fri, Feb 16, 2024 at 06:11:40PM +0900, Byungchul Park wrote: > On Fri, Feb 16, 2024 at 08:52:30AM +0100, Oscar Salvador wrote: > > On Fri, Feb 16, 2024 at 04:07:54PM +0900, Byungchul Park wrote: > > > For normal numa nodes, node_data[] is initialized at alloc_node_data(), > > > but it's not for memoryless node. However, the node *gets onlined* at > > > init_cpu_to_node(). > > > > > > Let's look at back free_area_init(). free_area_init_node() will be called > > > with node_data[] not set yet, because it's already *onlined*. So > > > ->zone_pgdat cannot be initialized properly in the path you mentioned. > > > > I am might be missing something., so bear with me. > > > > free_area_init() gets called before init_cpu_to_node() does. > > free_area_init_node() gets called on every possible node. > > > > free_area_init_node then() does > > > > pg_data_t *pgdat = NODE_DATA(nid);, > > > > and then we call free_area_init_core(). > > > > free_area_init_core() does > > > > free_area_init_core() does > > zone_init_internals() > > > > which ends up doing zone->zone_pgdat = NODE_DATA(nid); > > > > If node_data[] was not set at all, we would already blow up when doing > > the first > > > > for_each_node() > > pgdat = NODE_DATA(nid); > > free_area_init_node(nid); > > > > back in free_area_init(). > > It seems that I got it wrong about the reason. Let me check it again and > share the reason. > > Just in case, this patch is still definitely necessary tho. Sorry for the confusing expression. Please don't misunderstand it. The oops has been always observed in the configuration that I descriped. I meant: Just in case, I need to say the fix is still necessary. Byungchul
