On Sat, 17 Jun 2023 14:40:36 +1000 Liam Ni <zhiguangni01@xxxxxxxxx> wrote:
> __nr_to_section() may return a null pointer,
> before accessing the member variable section_mem_map,
> we should first determine whether it is a null pointer.
>
> ...
>
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -258,7 +258,7 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
> set_section_nid(section, nid);
>
> ms = __nr_to_section(section);
> - if (!ms->section_mem_map) {
> + if (ms && !ms->section_mem_map) {
> ms->section_mem_map = sparse_encode_early_nid(nid) |
> SECTION_IS_ONLINE;
> __section_mark_present(ms, section);
I'm suspecting that if __nr_to_section() returns NULL here, we should
just panic. But a null-deref gives the same information, so why change
things?
