Re: [PATCH v3] mm/memory_hotplug: refrain from adding memory into an impossible node
On Wed, 2020-04-15 at 12:43 +0200, Michal Hocko wrote:
On Tue 14-04-20 17:58:12, Vishal Verma wrote:
[...]
> +static int check_hotplug_node(int nid)
> +{
> + int alt_nid;
> +
> + if (node_possible(nid))
> + return nid;
> +
> + alt_nid = numa_map_to_online_node(nid);
> + if (alt_nid == NUMA_NO_NODE)
> + alt_nid = first_online_node;
> + WARN_TAINT(1, TAINT_FIRMWARE_WORKAROUND,
> + "node %d expected, but was absent from the node_possible_map, using %d
instead\n",
> + nid, alt_nid);
I really do not like this. Why should we try to be clever and change the
node id requested by the caller? I would just stick with node_possible
check and be done with this.
Hi Michal,
Being clever allows us to still use the memory even if it is in a non-
optimal configuration. Failing here leaves the user no path to add this
memory until the firmware is fixed. It is the tradeoff between some
usability vs. how loud we want to be for the failure.