[tip:sched/core] [sched/fair] c9d93a73ce: WARNING:suspicious_RCU_usage
From: kernel test robot
Date: Sat May 23 2026 - 09:27:24 EST
Hello,
kernel test robot noticed "WARNING:suspicious_RCU_usage" on:
commit: c9d93a73ce871ca32caf9308562501290b64b955 ("sched/fair: Drop redundant RCU read lock in NOHZ kick path")
https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core
in testcase: rcutorture
version:
with following parameters:
runtime: 300s
test: cpuhotplug
torture_type: tasks-rude
config: x86_64-randconfig-001-20260521
compiler: clang-20
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-lkp/202605232131.cfcd45a2-lkp@xxxxxxxxx
[ 102.159951][ T23]
[ 102.160730][ T23] =============================
[ 102.162072][ T23] WARNING: suspicious RCU usage
[ 102.163398][ T23] 7.1.0-rc2-00011-gc9d93a73ce87 #1 Not tainted
[ 102.165064][ T23] -----------------------------
[ 102.167687][ T23] kernel/sched/fair.c:12793 suspicious rcu_dereference_check() usage!
[ 102.169994][ T23]
[ 102.169994][ T23] other info that might help us debug this:
[ 102.169994][ T23]
[ 102.169994][ T23] other info that might help us debug this:
[ 102.169994][ T23]
[ 102.169994][ T23] other info that might help us debug this:
[ 102.169994][ T23]
[ 102.175418][ T23]
[ 102.175418][ T23] rcu_scheduler_active = 2, debug_locks = 1
[ 102.175418][ T23]
[ 102.175418][ T23] rcu_scheduler_active = 2, debug_locks = 1
[ 102.175418][ T23]
[ 102.175418][ T23] rcu_scheduler_active = 2, debug_locks = 1
[ 102.180431][ T23] 2 locks held by cpuhp/1/23:
[ 102.182158][ T23] #0: ffffffff872eadf0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun (cpu.c:545 cpu.c:1085)
[ 102.184843][ T23] #1: ffffffff872eaf20 (cpuhp_state-down){+.+.}-{0:0}, at: cpuhp_thread_fun (cpu.c:545 cpu.c:1085)
[ 102.187589][ T23]
[ 102.187589][ T23] stack backtrace:
[ 102.187589][ T23]
[ 102.187589][ T23] stack backtrace:
[ 102.187589][ T23]
[ 102.187589][ T23] stack backtrace:
[ 102.189233][ T23] CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 7.1.0-rc2-00011-gc9d93a73ce87 #1 PREEMPT
[ 102.189241][ T23] Call Trace:
[ 102.189245][ T23] <TASK>
[ 102.189251][ T23] __dump_stack (dump_stack.c:94)
[ 102.189260][ T23] dump_stack_lvl (dump_stack.c:120)
[ 102.189266][ T23] dump_stack (dump_stack.c:129)
[ 102.189270][ T23] lockdep_rcu_suspicious (locking/lockdep.c:6876)
[ 102.189279][ T23] set_cpu_sd_state_busy (sched/fair.c:12793)
[ 102.189286][ T23] nohz_balance_exit_idle (sched/fair.c:12812)
[ 102.189293][ T23] sched_cpu_deactivate (sched/core.c:8677)
[ 102.189300][ T23] ? trace_cpuhp_enter (trace/events/cpuhp.h:10)
[ 102.189305][ T23] ? balance_push_set (sched/sched.h:?)
[ 102.189312][ T23] cpuhp_invoke_callback (cpu.c:194)
[ 102.189315][ T23] ? lock_acquire (locking/lockdep.c:5868)
[ 102.189321][ T23] ? cpuhp_thread_fun (cpu.c:545 cpu.c:1085)
[ 102.189326][ T23] ? lock_acquire (locking/lockdep.c:5868)
[ 102.189337][ T23] cpuhp_thread_fun (cpu.c:1109)
[ 102.189341][ T23] ? cpuhp_thread_fun (cpu.c:545 cpu.c:1085)
[ 102.189350][ T23] ? cpuhp_should_run (cpu.c:?)
[ 102.189354][ T23] smpboot_thread_fn (smpboot.c:160)
[ 102.189364][ T23] ? smpboot_thread_fn (smpboot.c:?)
[ 102.189373][ T23] kthread (kthread.c:436)
[ 102.189379][ T23] ? smpboot_unregister_percpu_thread (smpboot.c:321)
[ 102.189385][ T23] ? kthread_unuse_mm (kthread.c:?)
[ 102.189392][ T23] ret_from_fork (x86/kernel/process.c:158)
[ 102.189397][ T23] ? kthread_unuse_mm (kthread.c:?)
[ 102.189402][ T23] ret_from_fork_asm (x86/entry/entry_64.S:245)
[ 102.189416][ T23] </TASK>
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260523/202605232131.cfcd45a2-lkp@xxxxxxxxx
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki