INFO: rcu detected stall in __hrtimer_run_queues

Status: upstream: reported on 2026/08/07 07:45
Reported-by: syzbot+2fd45289cdffd739600c@syzkaller.appspotmail.com
First crash: 96d, last: 13d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in __hrtimer_run_queues kernel 1 syz, C inconclusive done 22 1543d 2089d 0/29 auto-obsoleted due to no activity on 2022/12/19 03:45
upstream INFO: rcu detected stall in __hrtimer_run_queues (3) prio:high kernel 1 syz, C error 72 3d20h 94d 0/29 upstream: reported C repro on 2026/08/08 20:09
upstream INFO: rcu detected stall in __hrtimer_run_queues (2) kernel 1 1 497d 497d 0/29 auto-obsoleted due to no activity on 2025/09/29 21:02
upstream BUG: soft lockup in __hrtimer_run_queues (4) kernel 1 1 588d 584d 0/29 auto-obsoleted due to no activity on 2025/06/30 23:58
upstream BUG: soft lockup in __hrtimer_run_queues (2) kernel 1 1 864d 860d 0/29 auto-obsoleted due to no activity on 2024/09/27 22:42
upstream BUG: soft lockup in __hrtimer_run_queues (3) kernel 1 1 681d 677d 0/29 auto-obsoleted due to no activity on 2025/03/30 03:09
linux-6.1 BUG: soft lockup in __hrtimer_run_queues 1 1 39d 39d 0/3 upstream: reported on 2026/10/02 17:39

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (10501 ticks this GP) idle=8cb/1/0x4000000000000000 softirq=152509/152509 fqs=0 
	(t=10502 jiffies g=250161 q=1377)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10502 jiffies! g250161 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=76509
rcu: rcu_preempt kthread starved for 10505 jiffies! g250161 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:27424 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_cpu_stall+0x31a/0x5f0 kernel/rcu/tree_stall.h:631
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x6ec/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> af 17 80 f7 65 8b 05 30 2e 30 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90000d37a80 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 6cd128d429299700
RDX: dffffc0000000000 RSI: ffffffff8a2b2b60 RDI: 0000000000000001
RBP: ffffc90000d37b10 R08: ffff8880b8e2a243 R09: 1ffff110171c5448
R10: dffffc0000000000 R11: ffffed10171c5449 R12: dffffc0000000000
R13: ffff888024326170 R14: ffff8880b8e2a240 R15: 1ffff920001a6f50
 __run_hrtimer kernel/time/hrtimer.c:1681 [inline]
 __hrtimer_run_queues+0x402/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
 smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
NMI backtrace for cpu 0
CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x22d/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31f/0x5f0 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x6ec/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> af 17 80 f7 65 8b 05 30 2e 30 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90000d37a80 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 6cd128d429299700
RDX: dffffc0000000000 RSI: ffffffff8a2b2b60 RDI: 0000000000000001
RBP: ffffc90000d37b10 R08: ffff8880b8e2a243 R09: 1ffff110171c5448
R10: dffffc0000000000 R11: ffffed10171c5449 R12: dffffc0000000000
R13: ffff888024326170 R14: ffff8880b8e2a240 R15: 1ffff920001a6f50
 __run_hrtimer kernel/time/hrtimer.c:1681 [inline]
 __hrtimer_run_queues+0x402/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
 smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/29 03:39 linux-5.15.y 792fbe1537d8 b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in __hrtimer_run_queues
2026/10/21 05:38 linux-5.15.y 792fbe1537d8 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in __hrtimer_run_queues
2026/10/17 00:20 linux-5.15.y 792fbe1537d8 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in __hrtimer_run_queues
2026/08/07 07:44 linux-5.15.y aabd761612db c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in __hrtimer_run_queues
* Struck through repros no longer work on HEAD.