Re: [PATCH v4] hugetlb: Fix wrong use of nr_online_nodes

[Andrew Morton]

On Sat, 16 Apr 2022 10:35:26 +0000 Peng Liu <liupeng256@xxxxxxxxxx> wrote:

> Certain systems are designed to have sparse/discontiguous nodes. In
> this case, nr_online_nodes can not be used to walk through numa node.
> Also, a valid node may be greater than nr_online_nodes.
> 
> However, in hugetlb, it is assumed that nodes are contiguous. Recheck
> all the places that use nr_online_nodes, and repair them one by one.

oops.

What are the user-visible runtime effects of this flaw?