Re: failed NUMA pages inquiry status: Operation not permitted

Hi,

On Tue, Jan 27, 2026 at 12:32:28AM +0100, Tomas Vondra wrote:
> 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.

Should 09c37015d49665c52ae7eabd5852af36851aede4 be added to .git-blame-ignore-revs?

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com