INFO: rcu detected stall in call_timer_fn

Status: upstream: reported on 2025/09/20 00:57
Reported-by: syzbot+c4956fba553abbcc9f30@syzkaller.appspotmail.com
First crash: 394d, last: 9d16h
▶ ▼ Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: soft lockup in call_timer_fn net mm 1 19 811d 854d 0/29 auto-obsoleted due to no activity on 2024/10/08 10:43
linux-6.1 INFO: rcu detected stall in call_timer_fn 1 2 736d 808d 0/3 auto-obsoleted due to no activity on 2025/01/21 02:15
linux-4.19 INFO: rcu detected stall in call_timer_fn (2) 1 16 2175d 2449d 0/1 auto-closed as invalid on 2021/03/04 12:30
upstream INFO: rcu detected stall in call_timer_fn (5) net input usb 1 syz, C 9 466d 599d 0/29 upstream: reported C repro on 2025/02/27 04:11
linux-4.14 INFO: rcu detected stall in call_timer_fn (2) 1 1 2238d 2238d 0/1 auto-closed as invalid on 2020/12/31 22:00
upstream INFO: rcu detected stall in call_timer_fn (2) kernel 1 syz, C done error 47 1734d 2591d 0/29 closed as invalid on 2022/02/08 10:46
upstream INFO: rcu detected stall in call_timer_fn bpf net 1 2 2928d 2941d 0/29 closed as dup on 2019/01/02 16:26
linux-4.19 INFO: rcu detected stall in call_timer_fn 1 1 2589d 2589d 0/1 auto-closed as invalid on 2020/01/15 18:43
linux-6.1 INFO: rcu detected stall in call_timer_fn (2) 1 2 232d 252d 0/3 auto-obsoleted due to no activity on 2026/06/09 18:18
linux-4.14 INFO: rcu detected stall in call_timer_fn 1 5 2362d 2481d 0/1 auto-closed as invalid on 2020/08/29 09:07
upstream INFO: rcu detected stall in call_timer_fn (4) mm 1 1 992d 992d 0/29 auto-obsoleted due to no activity on 2024/03/31 10:44
upstream INFO: rcu detected stall in call_timer_fn (3) kernel 1 3 1474d 1489d 0/29 auto-obsoleted due to no activity on 2023/01/12 18:45
linux-6.1 INFO: rcu detected stall in call_timer_fn (3) 1 2 88d 101d 0/3 upstream: reported on 2026/07/10 22:14
linux-4.19 BUG: soft lockup in call_timer_fn 1 syz, C error 31 1325d 1927d 0/1 upstream: reported C repro on 2021/07/10 02:48
upstream BUG: soft lockup in call_timer_fn (2) trace 1 1 737d 733d 0/29 auto-obsoleted due to no activity on 2025/01/10 05:15

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P19093
	(detected by 0, t=10502 jiffies, g=58329, q=377)
task:syz.0.2996      state:R  running task     stack:24400 pid:19093 ppid: 14500 flags:0x0000400e
Call Trace:
 <IRQ>
 sched_show_task+0x459/0x580 kernel/sched/core.c:8659
 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:233 [inline]
 print_other_cpu_stall+0xec5/0x1270 kernel/rcu/tree_stall.h:573
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x845/0x1120 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+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x209/0x400 kernel/locking/lockdep.c:5741
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90000007a60 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 87f14f131a06c400
RDX: 0000000000000000 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4c00
RBP: ffffc90000007b68 R08: dffffc0000000000 R09: 1ffffffff2202a2b
R10: dffffc0000000000 R11: fffffbfff2202a2c R12: 1ffff92000000f58
R13: ffffc90000007bc0 R14: 0000000000000246 R15: dffffc0000000000
 call_timer_fn+0xe6/0x540 kernel/time/timer.c:1645
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 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:finish_lock_switch+0x12f/0x290 kernel/sched/core.c:4804
Code: 83 c7 18 be ff ff ff ff e8 be bc 6d 08 85 c0 74 46 4d 85 ff 75 62 0f 1f 44 00 00 48 89 df e8 58 2d 77 08 e8 a3 f2 2a 00 fb 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 2f 0e fe ff 43 80 3c 2c
RSP: 0018:ffffc9000319f2d8 EFLAGS: 00000286
RAX: 87f14f131a06c400 RBX: ffff888027743b80 RCX: 87f14f131a06c400
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4c00
RBP: 1ffff110171c7613 R08: ffffffff910150cf R09: 1ffffffff2202a19
R10: dffffc0000000000 R11: fffffbfff2202a1a R12: 1ffff110171c75c1
R13: dffffc0000000000 R14: ffff8880b8e3ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x650 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11cb/0x4350 kernel/sched/core.c:6395
 preempt_schedule_notrace+0xd9/0x120 kernel/sched/core.c:6650
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 rcu_is_watching+0x72/0xa0 kernel/rcu/tree.c:1124
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0xc7/0x400 kernel/locking/lockdep.c:5708
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 inet_twsk_purge+0x10d/0x820 net/ipv4/inet_timewait_sock.c:268
 ops_exit_list net/core/net_namespace.c:177 [inline]
 setup_net+0x842/0xa10 net/core/net_namespace.c:365
 copy_net_ns+0x33e/0x5b0 net/core/net_namespace.c:503
 create_new_namespaces+0x3ce/0x700 kernel/nsproxy.c:110
 copy_namespaces+0x378/0x3d0 kernel/nsproxy.c:178
 copy_process+0x17f0/0x3e70 kernel/fork.c:2295
 kernel_clone+0x23f/0x990 kernel/fork.c:2682
 __do_sys_clone kernel/fork.c:2799 [inline]
 __se_sys_clone kernel/fork.c:2783 [inline]
 __x64_sys_clone+0x19a/0x210 kernel/fork.c:2783
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4757b9e1d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4755df5fd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f4757e25fa0 RCX: 00007f4757b9e1d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000042164000
RBP: 00007f4757c35888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f4757e26038 R14: 00007f4757e25fa0 R15: 00007ffd65142938
 </TASK>

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/10 06:51 linux-5.15.y a051a4bf909f 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/09/27 06:20 linux-5.15.y 0248c33e835e a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/09/23 04:19 linux-5.15.y 0248c33e835e 5207b90e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/07/16 19:44 linux-5.15.y c86c4726e7f0 71b49442 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/07/02 10:03 linux-5.15.y eceeec79dbc6 27192279 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/06/07 20:23 linux-5.15.y dc027a595035 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/03/18 20:54 linux-5.15.y 91d48252ad4b 0199f9a1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/02/25 21:08 linux-5.15.y 3330a8d33e08 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2026/01/25 11:13 linux-5.15.y 9eec9a14ee10 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2025/11/30 15:21 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2025/11/30 11:57 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2025/10/23 14:22 linux-5.15.y ac56c046adf4 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
2025/09/20 00:57 linux-5.15.y 43bb85222e53 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in call_timer_fn
* Struck through repros no longer work on HEAD.