Re: [PATCH v3] mm: fix panic in __alloc_pages

Michal Hocko
2021-12-07T13:23:09Z

On Tue 07-12-21 13:28:31, David Hildenbrand wrote:
[...]
> But maybe I am missing something important regarding online vs. offline
> nodes that your patch changes?

I am relying on alloc_node_data setting the node online. But if we are
to change the call to arch_alloc_node_data then the patch needs to be
more involved. Here is what I have right now. If this happens to be the
right way then there is some additional work to sync up with the hotplug
code.

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c5952749ad40..a296e934ad2f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8032,8 +8032,23 @@ void __init free_area_init(unsigned long *max_zone_pfn)
/* Initialise every node */
mminit_verify_pageflags_layout();
setup_nr_node_ids();
- for_each_online_node(nid) {
- pg_data_t *pgdat = NODE_DATA(nid);
+ for_each_node(nid) {
+ pg_data_t *pgdat;
+
+ if (!node_online(nid)) {
+ pr_warn("Node %d uninitialized by the platform. Please report with memory map.\n", nid);
+ pgdat = arch_alloc_nodedata(nid);
+ pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat);
+ arch_refresh_nodedata(nid, pgdat);
+ node_set_online(nid);
+ /* TODO do we need register_one_node here or postpone to
+ * when any memory is onlined there
+ */
+ free_area_init_memoryless_node(nid);
+ continue;
+ }
+
+ pgdat = NODE_DATA(nid);
free_area_init_node(nid);

/* Any memory on that node */
--
Michal Hocko
SUSE Labs