Message-ID: <3b18ec96-5a45-4eaa-a98b-000927c9425b@vondra.me>
Date: Tue, 27 Jan 2026 00:32:28 +0100
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Subject: Re: failed NUMA pages inquiry status: Operation not permitted
From: Tomas Vondra <tomas@vondra.me>
To: Jakub Wartak <jakub.wartak@enterprisedb.com>
Cc: Christoph Berg <myon@debian.org>, pgsql-hackers@lists.postgresql.org
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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