linux-kernel - Re: [PATCH v2] kho: skip memoryless NUMA nodes when reserving scratch areas

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Message-ID: <2vxzecnkceqt.fsf@kernel.org>
Date: Tue, 20 Jan 2026 18:37:14 +0000
From: Pratyush Yadav <pratyush@...nel.org>
To: Evangelos Petrongonas <epetron@...zon.de>
Cc: Mike Rapoport <rppt@...nel.org>,  Pasha Tatashin
 <pasha.tatashin@...een.com>,  Pratyush Yadav <pratyush@...nel.org>,
  "Alexander Graf" <graf@...zon.com>,  Jason Miu <jasonmiu@...gle.com>,
  <linux-kernel@...r.kernel.org>,  <kexec@...ts.infradead.org>,
  <linux-mm@...ck.org>,  <nh-open-source@...zon.com>
Subject: Re: [PATCH v2] kho: skip memoryless NUMA nodes when reserving
 scratch areas

On Tue, Jan 20 2026, Evangelos Petrongonas wrote:

> kho_reserve_scratch() iterates over all online NUMA nodes to allocate
> per-node scratch memory. On systems with memoryless NUMA nodes (nodes
> that have CPUs but no memory), memblock_alloc_range_nid() fails because
> there is no memory available on that node. This causes KHO initialization
> to fail and kho_enable to be set to false.
>
> Some ARM64 systems have NUMA topologies where certain nodes contain only
> CPUs without any associated memory. These configurations are valid and
> should not prevent KHO from functioning.
>
> Fix this by only counting nodes that have memory (N_MEMORY state) and
> skip memoryless nodes in the per-node scratch allocation loop.
>
> Signed-off-by: Evangelos Petrongonas <epetron@...zon.de>

Reviewed-by: Pratyush Yadav <pratyush@...nel.org>

[...]

-- 
Regards,
Pratyush Yadav