Re: [PATCH v2 2/4] mm: handle uninitialized numa nodes gracefully

[Christoph Lameter]

On Tue, 14 Dec 2021, Michal Hocko wrote:

> This patch takes a different approach (following a lead of [3]) and it
> pre allocates pgdat for all possible nodes in an arch indipendent code
> - free_area_init. All uninitialized nodes are treated as memoryless
> nodes. node_state of the node is not changed because that would lead to
> other side effects - e.g. sysfs representation of such a node and from
> past discussions [4] it is known that some tools might have problems
> digesting that.

Would it be possible to define a pgdat statically and place it in read
only memory? Populate with values that ensure that the page allocator
does not blow up but does a defined fallback.

Point the pgdat for all nodes not online to that readonly pgdat?

Maybe that would save some memory. When the node comes online then a real
pgdat could be allocated.