hi, Paul,
the similar issue still exists on this dev.2025.08.21a branch.
again, if the issue is already fixed on later branches, please just ignore.
thanks
Hello,
kernel test robot noticed
"WARNING:possible_circular_locking_dependency_detected" on:
commit: 8bd9383727068a5a18acfecefbdfa44a7d6bd838 ("rcu: Re-implement RCU Tasks
Trace in terms of SRCU-fast")
https://github.com/paulmckrcu/linux dev.2025.08.21a
in testcase: rcutorture
version:
with following parameters:
runtime: 300s
test: default
torture_type: tasks-tracing
config: x86_64-randconfig-003-20250824
compiler: clang-20
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
(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.s...@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202508261642.b15eefbb-...@intel.com
[ 42.365933][ T393] WARNING: possible circular locking dependency detected
[ 42.366428][ T393] 6.17.0-rc1-00035-g8bd938372706 #1 Tainted: G
T
[ 42.366985][ T393] ------------------------------------------------------
[ 42.367490][ T393] rcu_torture_rea/393 is trying to acquire lock:
[ 42.367952][ T393] ffffffffad41dc88
(rcu_tasks_trace_srcu_struct.srcu_wq.lock){....}-{2:2}, at: swake_up_one
(kernel/sched/swait.c:52 (discriminator 1))
[ 42.368775][ T393]
[ 42.368775][ T393] but task is already holding lock:
[ 42.369278][ T393] ffff88813d1ff2e8 (&p->pi_lock){-.-.}-{2:2}, at:
rcutorture_one_extend (kernel/rcu/rcutorture.c:?) rcutorture
[ 42.370043][ T393]
[ 42.370043][ T393] which lock already depends on the new lock.
[ 42.370043][ T393]
[ 42.370755][ T393]
[ 42.370755][ T393] the existing dependency chain (in reverse order) is:
[ 42.371388][ T393]
[ 42.371388][ T393] -> #1 (&p->pi_lock){-.-.}-{2:2}:
[ 42.371903][ T393] _raw_spin_lock_irqsave
(include/linux/spinlock_api_smp.h:110 kernel/locking/spinlock.c:162)
[ 42.372309][ T393] try_to_wake_up (include/linux/spinlock.h:557 (discriminator
1) kernel/sched/core.c:4216 (discriminator 1))
[ 42.372669][ T393] swake_up_locked (include/linux/list.h:111)
[ 42.373029][ T393] swake_up_one (kernel/sched/swait.c:54 (discriminator 1))
[ 42.373380][ T393] tasks_tracing_torture_read_unlock (include/linux/srcu.h:408
(discriminator 1) include/linux/rcupdate_trace.h:81 (discriminator 1)
kernel/rcu/rcutorture.c:1112 (discriminator 1)) rcutorture
[ 42.373952][ T393] rcutorture_one_extend (kernel/rcu/rcutorture.c:2141)
rcutorture
[ 42.374452][ T393] rcu_torture_one_read_end (kernel/rcu/rcutorture.c:2357)
rcutorture
[ 42.374976][ T393] rcu_torture_one_read (kernel/rcu/rcutorture.c:?) rcutorture
[ 42.375460][ T393] rcu_torture_reader (kernel/rcu/rcutorture.c:2443)
rcutorture
[ 42.375920][ T393] kthread (kernel/kthread.c:465)
[ 42.376241][ T393] ret_from_fork (arch/x86/kernel/process.c:154)
[ 42.376603][ T393] ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
[ 42.376973][ T393]
[ 42.376973][ T393] -> #0
(rcu_tasks_trace_srcu_struct.srcu_wq.lock){....}-{2:2}:
[ 42.377657][ T393] __lock_acquire (kernel/locking/lockdep.c:3166)
[ 42.378031][ T393] lock_acquire (kernel/locking/lockdep.c:5868)
[ 42.378378][ T393] _raw_spin_lock_irqsave
(include/linux/spinlock_api_smp.h:110 kernel/locking/spinlock.c:162)
[ 42.378794][ T393] swake_up_one (kernel/sched/swait.c:52 (discriminator 1))
[ 42.379152][ T393] tasks_tracing_torture_read_unlock (include/linux/srcu.h:408
(discriminator 1) include/linux/rcupdate_trace.h:81 (discriminator 1)
kernel/rcu/rcutorture.c:1112 (discriminator 1)) rcutorture
[ 42.379714][ T393] rcutorture_one_extend (kernel/rcu/rcutorture.c:2141)
rcutorture
[ 42.380217][ T393] rcu_torture_one_read_end (kernel/rcu/rcutorture.c:2357)
rcutorture
[ 42.380731][ T393] rcu_torture_one_read (kernel/rcu/rcutorture.c:?) rcutorture
[ 42.381220][ T393] rcu_torture_reader (kernel/rcu/rcutorture.c:2443)
rcutorture
[ 42.381714][ T393] kthread (kernel/kthread.c:465)
[ 42.382060][ T393] ret_from_fork (arch/x86/kernel/process.c:154)
[ 42.382420][ T393] ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
[ 42.382796][ T393]
[ 42.382796][ T393] other info that might help us debug this:
[ 42.382796][ T393]
[ 42.383515][ T393] Possible unsafe locking scenario:
[ 42.383515][ T393]
[ 42.384052][ T393] CPU0 CPU1
[ 42.384428][ T393] ---- ----
[ 42.384799][ T393] lock(&p->pi_lock);
[ 42.385083][ T393]
lock(rcu_tasks_trace_srcu_struct.srcu_wq.lock);
[ 42.385707][ T393] lock(&p->pi_lock);
[ 42.386180][ T393] lock(rcu_tasks_trace_srcu_struct.srcu_wq.lock);
[ 42.386663][ T393]
[ 42.386663][ T393] *** DEADLOCK ***
[ 42.386663][ T393]
[ 42.387236][ T393] 1 lock held by rcu_torture_rea/393:
[ 42.387626][ T393] #0: ffff88813d1ff2e8 (&p->pi_lock){-.-.}-{2:2}, at:
rcutorture_one_extend (kernel/rcu/rcutorture.c:?) rcutorture
[ 42.388419][ T393]
[ 42.388419][ T393] stack backtrace:
[ 42.388852][ T393] CPU: 0 UID: 0 PID: 393 Comm: rcu_torture_rea Tainted: G
T 6.17.0-rc1-00035-g8bd938372706 #1 PREEMPT(full)
[ 42.389758][ T393] Tainted: [T]=RANDSTRUCT
[ 42.390057][ T393] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[ 42.390786][ T393] Call Trace:
[ 42.391020][ T393] <TASK>
[ 42.391225][ T393] dump_stack_lvl (lib/dump_stack.c:123 (discriminator 2))
[ 42.391544][ T393] print_circular_bug (kernel/locking/lockdep.c:2045)
[ 42.391898][ T393] check_noncircular (kernel/locking/lockdep.c:?)
[ 42.392242][ T393] __lock_acquire (kernel/locking/lockdep.c:3166)
[ 42.392594][ T393] ? __schedule (kernel/sched/sched.h:1531 (discriminator 1)
kernel/sched/core.c:6969 (discriminator 1))
[ 42.392930][ T393] ? lock_release (kernel/locking/lockdep.c:470 (discriminator
3))
[ 42.393272][ T393] ? swake_up_one (kernel/sched/swait.c:52 (discriminator 1))
[ 42.393610][ T393] lock_acquire (kernel/locking/lockdep.c:5868)
[ 42.393930][ T393] ? swake_up_one (kernel/sched/swait.c:52 (discriminator 1))
[ 42.394264][ T393] _raw_spin_lock_irqsave
(include/linux/spinlock_api_smp.h:110 kernel/locking/spinlock.c:162)
[ 42.394640][ T393] ? swake_up_one (kernel/sched/swait.c:52 (discriminator 1))
[ 42.394969][ T393] swake_up_one (kernel/sched/swait.c:52 (discriminator 1))
[ 42.395281][ T393] tasks_tracing_torture_read_unlock (include/linux/srcu.h:408
(discriminator 1) include/linux/rcupdate_trace.h:81 (discriminator 1)
kernel/rcu/rcutorture.c:1112 (discriminator 1)) rcutorture
[ 42.395814][ T393] rcutorture_one_extend (kernel/rcu/rcutorture.c:2141)
rcutorture
[ 42.396276][ T393] rcu_torture_one_read_end (kernel/rcu/rcutorture.c:2357)
rcutorture
[ 42.396756][ T393] rcu_torture_one_read (kernel/rcu/rcutorture.c:?) rcutorture
[ 42.397219][ T393] ? __cfi_rcu_torture_reader (kernel/rcu/rcutorture.c:2426)
rcutorture
[ 42.397690][ T393] rcu_torture_reader (kernel/rcu/rcutorture.c:2443)
rcutorture
[ 42.398126][ T393] ? __cfi_rcu_torture_timer (kernel/rcu/rcutorture.c:2405)
rcutorture
[ 42.398565][ T393] kthread (kernel/kthread.c:465)
[ 42.398857][ T393] ? __cfi_kthread (kernel/kthread.c:412)
[ 42.399169][ T393] ret_from_fork (arch/x86/kernel/process.c:154)
[ 42.399491][ T393] ? __cfi_kthread (kernel/kthread.c:412)
[ 42.399815][ T393] ret_from_fork_asm (arch/x86/entry/entry_64.S:255)
[ 42.400151][ T393] </TASK>
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250826/202508261642.b15eefbb-...@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
