When the kernel is built with CONFIG_DEBUG_PER_CPU_MAPS, the cpumap code
can trigger a spurious warning if CONFIG_CPUMASK_OFFSTACK is also set. This
happens because in this configuration, NR_CPUS can be larger than
nr_cpumask_bits, so the initial check in cpu_map_alloc() is not sufficient
to guard against hitting the warning in cpumask_check().
Fix this by using the nr_cpumask_bits variable in the map creation code
instead of the NR_CPUS constant.
Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Reported-by: Xiumei Mu <xmu@xxxxxxxxxx>
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
kernel/bpf/cpumap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index 70f71b154fa5..23902afb3bba 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -99,8 +99,8 @@ static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
bpf_map_init_from_attr(&cmap->map, attr);
- /* Pre-limit array size based on NR_CPUS, not final CPU check */
- if (cmap->map.max_entries > NR_CPUS) {
+ /* Pre-limit array size based on nr_cpumask_bits, not final CPU check */
+ if (cmap->map.max_entries > nr_cpumask_bits) {
err = -E2BIG;
goto free_cmap;
}
--
2.26.0
