Message-ID: <20d4c8a3-a402-4426-a912-8261e8923adf@vondra.me>
Date: Thu, 16 Oct 2025 17:09:59 +0200
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: failed NUMA pages inquiry status: Operation not permitted
To: Christoph Berg <myon@debian.org>
Cc: Tomas Vondra <tomas.vondra@postgresql.org>,
 Jakub Wartak <jakub.wartak@enterprisedb.com>,
 pgsql-hackers@lists.postgresql.org
References: <E1u1tr8-003BbN-2E@gemulon.postgresql.org>
 <aPDZOxjrmEo_1JRG@msg.df7cb.de>
 <7bbc582b-cc70-4a6f-bbf2-b5fd9b13a867@vondra.me>
 <aPEHINwaAxsQNAIP@msg.df7cb.de>
Content-Language: en-US
From: Tomas Vondra <tomas@vondra.me>
In-Reply-To: <aPEHINwaAxsQNAIP@msg.df7cb.de>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/20d4c8a3-a402-4426-a912-8261e8923adf%40vondra.me>
Precedence: bulk


On 10/16/25 16:54, Christoph Berg wrote:
> Re: Tomas Vondra
>> It's probably more about the kernel version. What kernels are used by
>> these systems?
> 
> It's the very same kernel, just different docker containers on the
> same system. I did not investigate yet where the problem is coming
> from, different libnuma versions seemed like the best bet.
> 
> Same (differing) results on both these systems:
> Linux turing 6.16.7+deb14-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.16.7-1 (2025-09-11) x86_64 GNU/Linux
> Linux jenkins 6.1.0-39-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.148-1 (2025-08-26) x86_64 GNU/Linux
> 

Hmmm. Those seem like relatively recent kernels.

>> Not sure how would that work. It seems this is some sort of permission
>> check in numa_move_pages, that's not what pg_numa_available does. Also,
>> it may depending on the page queried (e.g. whether it's exclusive or
>> shared by multiple processes).
> 
> It's probably the lack of some process capability in that environment.
> Maybe there is a way to query that, but I don't know much about that
> yet.
> 

move_page() manpage mentions PTRACE_MODE_READ_REALCREDS (man ptrace) so
maybe that's it.

-- 
Tomas Vondra