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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: 68d, last: 13d
▶ ▼ Similar bugs (6)
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 764d 1215d 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 5 7d15h 280d 0/3 upstream: reported syz repro on 2025/10/14 11:53
upstream INFO: rcu detected stall in sys_clock_adjtime kernel 1 C done inconclusive 174 1d22h 2205d 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 244d 256d 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 C error 58 11d 1202d 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 582d 589d 0/3 auto-obsoleted due to no activity on 2025/03/26 12:12

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=428c/1/0x4000000000000000 softirq=79706/79709 fqs=0
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P17757/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=113181, q=164 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 21217 Comm: syz.1.3864 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:check_preemption_disabled+0x47/0x110 lib/smp_processor_id.c:55
Code: 77 75 65 8b 0d d2 da 77 75 f7 c1 ff ff ff 7f 74 1f 65 48 8b 0c 25 28 00 00 00 48 3b 4c 24 08 0f 85 c4 00 00 00 48 83 c4 10 5b <41> 5e 41 5f 5d c3 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00
RSP: 0018:ffffc90000007c30 EFLAGS: 00000086
RAX: 0000000000000000 RBX: ffff888028840000 RCX: 8b55080f681a4100
RDX: ffff888028840000 RSI: ffffffff8acadce0 RDI: ffffffff8b1cfa20
RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f84 R12: 0000000000000000
R13: 0000000000000046 R14: ffff88802f594300 R15: ffff888028840ae0
FS:  00007f2a6e0076c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d615ff8 CR3: 000000004bda7000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
 lock_is_held_type+0x104/0x190 kernel/locking/lockdep.c:5826
 lock_is_held include/linux/lockdep.h:288 [inline]
 advance_sched+0x152/0xc70 net/sched/sch_taprio.c:944
 __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> 9b ed c6 f6 65 8b 05 6c 3c 6e 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900101a7a20 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: 8b55080f681a4100
RDX: dffffc0000000000 RSI: ffffffff8acacb60 RDI: 0000000000000001
RBP: ffffc900101a7ab0 R08: ffffffff8e8c6b2f R09: 1ffffffff1d18d65
R10: dffffc0000000000 R11: fffffbfff1d18d66 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff8d14b5c0 R15: 1ffff92002034f44
 timekeeping_inject_offset+0x5c6/0x670 kernel/time/timekeeping.c:1392
 do_adjtimex+0x47c/0xa10 kernel/time/timekeeping.c:2444
 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: 0033:0x7f2a6d19de59
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:00007f2a6e007028 EFLAGS: 00000246 ORIG_RAX: 0000000000000131
RAX: ffffffffffffffda RBX: 00007f2a6d426360 RCX: 00007f2a6d19de59
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000000
RBP: 00007f2a6d233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2a6d4263f8 R14: 00007f2a6d426360 R15: 00007ffe52fba638
 </TASK>
task:kworker/u4:26   state:R  running task     stack:22664 pid:17757 ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692
RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
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: 0000:ffffc900185ffa40 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: b0f774b8c954bf00
RDX: 0000000000000000 RSI: ffffffff8acadce0 RDI: ffffffff8b1cfa20
RBP: ffffc900185ffb48 R08: dffffc0000000000 R09: 1ffffffff223cea0
R10: dffffc0000000000 R11: fffffbfff223cea1 R12: 1ffff920030bff54
R13: ffffffff8d131da0 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline]
 batadv_nc_worker+0xef/0x600 net/batman-adv/network-coding.c:719
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
 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: rcu_preempt kthread starved for 10502 jiffies! g113181 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:27832 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 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: 8442 Comm: kworker/u4:13 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215
Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d ec 87 05 0d 48 89 de 5b e9 23 a7 57 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d c0 d2 7c 7e 65 8b 15 c1 d2 7c 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc9001861f778 EFLAGS: 00000202
RAX: ffffffff817bf7fd RBX: 1ffff110171c87a9 RCX: ffff88807a983c00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9001861f900 R08: ffffffff911e7507 R09: 1ffffffff223cea0
R10: dffffc0000000000 R11: fffffbfff223cea1 R12: ffff8880b8e43d48
R13: ffff8880b8f3d3c0 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe5ebc27dac CR3: 000000000cf32000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:311 [inline]
 smp_call_function_many_cond+0xd9d/0x1190 kernel/smp.c:855
 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:2653 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2730
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2811
 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 (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.