From 3ee5333feec43b4c75c8d3dc70f4c776b7c1b3ed Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 16 Feb 2026 15:02:33 +0100 Subject: [PATCH] s390/smp: Avoid calling rebuild_sched_domains() early Since a recent cpuset code change [1] the kernel emits warnings like this: WARNING: kernel/cgroup/cpuset.c:966 at rebuild_sched_domains_locked+0xe0/0x120, CPU#0: kworker/0:0/9 Modules linked in: CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.20.0-20260215.rc0.git3.bb7a3fc2c976.300.fc43.s390x+git #1 PREEMPTLAZY Hardware name: IBM 3931 A01 703 (KVM/Linux) Workqueue: events topology_work_fn Krnl PSW : 0704c00180000000 000002922e7af5c4 (rebuild_sched_domains_locked+0xe4/0x120) ... Call Trace: [<000002922e7af5c4>] rebuild_sched_domains_locked+0xe4/0x120 [<000002922e7af634>] rebuild_sched_domains+0x34/0x50 [<000002922e6ba232>] process_one_work+0x1b2/0x490 [<000002922e6bc4b8>] worker_thread+0x1f8/0x3b0 [<000002922e6c6a98>] kthread+0x148/0x170 [<000002922e645ffc>] __ret_from_fork+0x3c/0x240 [<000002922f51f492>] ret_from_fork+0xa/0x30 Reason for this is that the s390 specific smp initialization code schedules a work which rebuilds scheduling domains way before the scheduler is smp aware. With the mentioned commit the (invalid) rebuild request is not anymore silently discarded but instead leads to warning. Address this by avoiding the early rebuild request. Reported-by: Marc Hartmayer Tested-by: Marc Hartmayer Fixes: 6ee43047e8ad ("cpuset: Remove unnecessary checks in rebuild_sched_domains_locked") [1] Signed-off-by: Heiko Carstens --- arch/s390/kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index b7429f30afc1..eb334539444a 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -1151,7 +1151,7 @@ int __ref smp_rescan_cpus(bool early) smp_get_core_info(info, 0); nr = __smp_rescan_cpus(info, early); kfree(info); - if (nr) + if (nr && !early) topology_schedule_update(); return 0; } -- 2.30.2