INFO: rcu detected stall in sys_clock_adjtime (2)

Status: upstream: reported on 2026/05/14 12:23
Reported-by: syzbot+781e8ba5e868d69673f4@syzkaller.appspotmail.com
First crash: 159d, last: 7h31m
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_clock_adjtime 1 28 855d 1306d 0/3 auto-obsoleted due to no activity on 2024/09/25 13:11
linux-6.1 INFO: rcu detected stall in sys_clock_adjtime (3) origin:upstream 1 syz error 11 47d 371d 0/3 upstream: reported syz repro on 2025/10/14 11:53
upstream INFO: rcu detected stall in sys_clock_adjtime kernel 1 syz, C done inconclusive 201 6h57m 2296d 0/29 upstream: reported C repro on 2020/07/07 15:13
linux-6.6 INFO: rcu detected stall in sys_clock_adjtime 1 2 336d 347d 0/2 auto-obsoleted due to no activity on 2026/02/26 19:58
linux-5.15 INFO: rcu detected stall in sys_clock_adjtime origin:upstream 1 syz, C error 61 26d 1293d 0/3 upstream: reported C repro on 2023/04/06 18:02
linux-6.1 INFO: rcu detected stall in sys_clock_adjtime (2) 1 3 673d 680d 0/3 auto-obsoleted due to no activity on 2025/03/26 12:12
upstream BUG: workqueue lockup (5) prio:low arm 1 syz, C done 18002 1h50m 2471d 0/29 upstream: reported C repro on 2020/01/14 22:04

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (0 ticks this GP) idle=4264/1/0x4000000000000000 softirq=35533/35533 fqs=1
rcu: 	(detected by 1, t=10502 jiffies, g=47437, q=116 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10957 Comm: syz.3.1697 Tainted: G S                 syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:lock_release+0x5c0/0x8c0 kernel/locking/lockdep.c:5814
Code: 04 2f 00 00 00 00 43 c7 44 2f 08 00 00 00 00 65 48 8b 04 25 28 00 00 00 48 3b 84 24 c0 00 00 00 0f 85 8b 00 00 00 48 8d 65 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b e9 bd fa ff ff 0f 0b 48 c7
RSP: 0018:ffffc90000007c50 EFLAGS: 00000046
RAX: 72c837c508d14000 RBX: 58cce5e7c8d5ebdc RCX: 72c837c508d14000
RDX: 0000000000000001 RSI: ffffffff8acae160 RDI: ffffffff8b1d5160
RBP: ffffc90000007c78 R08: ffffffff8f6c5aef R09: 1ffffffff1ed8b5d
R10: dffffc0000000000 R11: fffffbfff1ed8b5e R12: ffff88802490e510
R13: dffffc0000000000 R14: ffff88802490e4d8 R15: 1ffff92000000f78
FS:  00007f9f5d7a56c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000440 CR3: 0000000037aed000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
 _raw_spin_unlock+0x16/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 advance_sched+0x989/0xc70 net/sched/sch_taprio.c:998
 __run_hrtimer kernel/time/hrtimer.c:1754 [inline]
 __hrtimer_run_queues+0x525/0xc10 kernel/time/hrtimer.c:1818
 hrtimer_interrupt+0x39d/0x980 kernel/time/hrtimer.c:1880
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xc0/0x120 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> ab 35 c0 f6 65 8b 05 1c f3 66 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900034578c0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 72c837c508d14000
RDX: dffffc0000000000 RSI: ffffffff8acacfe0 RDI: 0000000000000001
RBP: ffffc90003457940 R08: ffffffff8f6c5aef R09: 1ffffffff1ed8b5d
R10: dffffc0000000000 R11: fffffbfff1ed8b5e R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888030e71c88 R15: 1ffff9200068af18
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 timerfd_clock_was_set+0x1cb/0x2c0 fs/timerfd.c:113
 clock_was_set+0x788/0x800 kernel/time/hrtimer.c:996
 timekeeping_inject_offset+0x5d0/0x670 kernel/time/timekeeping.c:1395
 do_adjtimex+0x47c/0xa10 kernel/time/timekeeping.c:2450
 do_clock_adjtime kernel/time/posix-timers.c:1160 [inline]
 __do_sys_clock_adjtime kernel/time/posix-timers.c:1172 [inline]
 __se_sys_clock_adjtime kernel/time/posix-timers.c:1163 [inline]
 __x64_sys_clock_adjtime+0x244/0x320 kernel/time/posix-timers.c:1163
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9f5c99f559
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:00007f9f5d7a5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000131
RAX: ffffffffffffffda RBX: 00007f9f5cc25fa0 RCX: 00007f9f5c99f559
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f9f5ca36b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f5cc26038 R14: 00007f9f5cc25fa0 R15: 00007ffda3a01198
 </TASK>
rcu: rcu_preempt kthread starved for 10495 jiffies! g47437 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:R  running task     stack:27848 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 7043 Comm: kworker/u4:14 Tainted: G S                 syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:311 [inline]
RIP: 0010:smp_call_function_many_cond+0xd85/0x1190 kernel/smp.c:855
Code: 45 8b 34 24 44 89 f6 83 e6 01 31 ff e8 34 01 0b 00 41 83 e6 01 49 be 00 00 00 00 00 fc ff df 75 07 e8 6f fd 0a 00 eb 38 f3 90 <42> 0f b6 04 33 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 53 fd
RSP: 0018:ffffc900190bf780 EFLAGS: 00000293
RAX: ffffffff817c935d RBX: 1ffff110171887a5 RCX: ffff88802c408000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900190bf900 R08: ffffffff91ff1507 R09: 1ffffffff23fe2a0
R10: dffffc0000000000 R11: fffffbfff23fe2a1 R12: ffff8880b8c43d28
R13: ffff8880b8d3d380 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd67a15da08 CR3: 000000000dd32000 CR4: 00000000003506e0
DR0: 0000000000010000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1022
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:2222 [inline]
 text_poke_bp_batch+0x31e/0x980 arch/x86/kernel/alternative.c:2432
 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x123/0x240 kernel/jump_label.c:207
 static_key_enable+0x1a/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xa8/0x260 mm/kfence/core.c:847
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/20 15:12 linux-6.6.y cecd39af8a1a df8746fb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/10/02 05:08 linux-6.6.y 79643295eba1 6d32eb1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/09/22 09:15 linux-6.6.y 79643295eba1 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/09/22 08:37 linux-6.6.y 79643295eba1 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/09/22 08:35 linux-6.6.y 79643295eba1 e12281bd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/09/02 19:00 linux-6.6.y 8b73de7da85f 85995287 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/09/02 18:58 linux-6.6.y 8b73de7da85f 85995287 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/07/28 06:17 linux-6.6.y c5596480c50e 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/07/08 13:13 linux-6.6.y da47cbc25466 88a4b44c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/06/14 05:37 linux-6.6.y 924b4a879cbb 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/05/23 14:59 linux-6.6.y 0a40c6fbd105 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/05/23 04:25 linux-6.6.y eac8889a3a1c c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/05/15 00:36 linux-6.6.y 3b9f64db0496 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
2026/05/14 12:23 linux-6.6.y 3b9f64db0496 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in sys_clock_adjtime
* Struck through repros no longer work on HEAD.