From: Evangelos Petrongonas Date: Tue, 20 Jan 2026 17:59:11 +0000 (+0000) Subject: kho: skip memoryless NUMA nodes when reserving scratch areas X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=427b2535f51342de3156babc6bdc3f3b7dd2c707;p=thirdparty%2Fkernel%2Flinux.git kho: skip memoryless NUMA nodes when reserving scratch areas 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. Link: https://lkml.kernel.org/r/20260120175913.34368-1-epetron@amazon.de Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers"). Signed-off-by: Evangelos Petrongonas Reviewed-by: Pratyush Yadav Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Pasha Tatashin Cc: Alexander Graf Cc: Signed-off-by: Andrew Morton --- diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index e0a50b012ba36..8a2b2a7e50fc6 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -655,7 +655,7 @@ static void __init kho_reserve_scratch(void) scratch_size_update(); /* FIXME: deal with node hot-plug/remove */ - kho_scratch_cnt = num_online_nodes() + 2; + kho_scratch_cnt = nodes_weight(node_states[N_MEMORY]) + 2; size = kho_scratch_cnt * sizeof(*kho_scratch); kho_scratch = memblock_alloc(size, PAGE_SIZE); if (!kho_scratch) { @@ -691,7 +691,11 @@ static void __init kho_reserve_scratch(void) kho_scratch[i].size = size; i++; - for_each_online_node(nid) { + /* + * Loop over nodes that have both memory and are online. Skip + * memoryless nodes, as we can not allocate scratch areas there. + */ + for_each_node_state(nid, N_MEMORY) { size = scratch_size_node(nid); addr = memblock_alloc_range_nid(size, CMA_MIN_ALIGNMENT_BYTES, 0, MEMBLOCK_ALLOC_ACCESSIBLE,