From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Evangelos Petrongonas <epetron@amazon.de>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Pratyush Yadav <pratyush@kernel.org>,
Alexander Graf <graf@amazon.com>, Jason Miu <jasonmiu@google.com>,
linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
linux-mm@kvack.org, nh-open-source@amazon.com
Subject: Re: [PATCH v2] kho: skip memoryless NUMA nodes when reserving scratch areas
Date: Fri, 23 Jan 2026 10:53:42 +0200 [thread overview]
Message-ID: <aXM3FoK7g12P5h91@kernel.org> (raw)
In-Reply-To: <20260122152112.1a8be8e7bdab72631234cd69@linux-foundation.org>
On Thu, Jan 22, 2026 at 03:21:12PM -0800, Andrew Morton wrote:
> On Tue, 20 Jan 2026 17:59:11 +0000 Evangelos Petrongonas <epetron@amazon.de> 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.
> >
>
> So kho is unusable on such machines.
>
> Should we backport this? I'm thinking
>
> Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers").
It's only for v6.18, but sure, why not.
--
Sincerely yours,
Mike.
prev parent reply other threads:[~2026-01-23 8:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-20 17:59 Evangelos Petrongonas
2026-01-20 18:37 ` Pratyush Yadav
2026-01-20 19:00 ` Mike Rapoport
2026-01-22 18:18 ` Pasha Tatashin
2026-01-22 23:21 ` Andrew Morton
2026-01-23 8:53 ` Mike Rapoport [this message]
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