On Tue, Jan 20, 2026 at 05:59:11PM +0000, 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 <[email protected]>
Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> > --- > v2: > - Removed kho_mem_nodes_count in favour of nodes_weight(nodes_state[N_MEMORY]) > - Use for_each_node_state(nid, N_MEMORY) to loop over nodes that are both > online and have memory. > TIL: Nodes in N_MEMORY are a subset of those that are online. Thanks Mike :) > > kernel/liveupdate/kexec_handover.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/kernel/liveupdate/kexec_handover.c > b/kernel/liveupdate/kexec_handover.c > index 9dc51fab604f..979ebaf015bf 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -643,7 +643,7 @@ 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) > @@ -673,7 +673,11 @@ 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, > -- > 2.43.0 > > > > > Amazon Web Services Development Center Germany GmbH > Tamara-Danz-Str. 13 > 10243 Berlin > Geschaeftsfuehrung: Christof Hellmis, Andreas Stieger > Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B > Sitz: Berlin > Ust-ID: DE 365 538 597 > -- Sincerely yours, Mike.
