Re: failed NUMA pages inquiry status: Operation not permitted

On 1/16/26 22:29, Tomas Vondra wrote:
> Hi,
>
> Here's WIP fix for the root cause, i.e. handling status -2 in the two
> views querying NUMA node for memory pages:
>
> * pg_shmem_allocations_numa
> * pg_buffercache_numa
>
> We can't prevent -2 from happening - the kernel can move arbitrary pages
> to swap, we have no control over it. So I think we need to handle -2 as
> "unknown" node, instead of failing. The patch simply returns NULL
> instead of the node, but in principle we might return some other value
> (but IMHO we should not return the raw status, the -2 makes no sense in
> our context, it's some internal kernel errno).
>
> The pg_buffercache_numa was not failing, it just returned the -2 status
> verbatim. But I modified it to return NULL, for consistency.
>
> AFAIK this will fix the regression tests too - they only check COUNT(*),
> not the actual values.
>
> I'm not sure if we need to mention this in the docs. It probably should
> mention the column can be NULL, which means "unknown node".
>

Pushed and backpatched to 18. Hopefully that fixes this.

regards

--
Tomas Vondra