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

David Hildenbrand
2021-12-13T15:07:28Z

On 13.12.21 16:06, Michal Hocko wrote:
> On Thu 09-12-21 11:48:42, Michal Hocko wrote:
> [...]
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 852041f6be41..2d38a431f62f 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1161,19 +1161,21 @@ static void reset_node_present_pages(pg_data_t *pgdat)
>> }
>>
>> /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
>> -static pg_data_t __ref *hotadd_new_pgdat(int nid)
>> +static pg_data_t __ref *hotadd_init_pgdat(int nid)
>> {
>> struct pglist_data *pgdat;
>>
>> pgdat = NODE_DATA(nid);
>> - if (!pgdat) {
>> - pgdat = arch_alloc_nodedata(nid);
>> - if (!pgdat)
>> - return NULL;
>>
>> + /*
>> + * NODE_DATA is preallocated (free_area_init) but its internal
>> + * state is not allocated completely. Add missing pieces.
>> + * Completely offline nodes stay around and they just need
>> + * reintialization.
>> + */
>> + if (!pgdat->per_cpu_nodestats) {
>> pgdat->per_cpu_nodestats =
>> alloc_percpu(struct per_cpu_nodestat);
>> - arch_refresh_nodedata(nid, pgdat);
>
> This should really be
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 42211485bcf3..2daa88ce8c80 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1173,7 +1173,7 @@ static pg_data_t __ref *hotadd_init_pgdat(int nid)
> * Completely offline nodes stay around and they just need
> * reintialization.
> */
> - if (!pgdat->per_cpu_nodestats) {
> + if (pgdat->per_cpu_nodestats == &boot_nodestats) {
> pgdat->per_cpu_nodestats =
> alloc_percpu(struct per_cpu_nodestat);
> } else {
>

I'll try giving this some churn later this week -- busy with other stuff.

--
Thanks,

David / dhildenb