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: 162d, last: 2d20h
▶ ▼ 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 858d 1309d 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 50d 374d 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 3d04h 2299d 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 339d 350d 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 29d 1296d 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 676d 683d 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 18020 1h10m 2473d 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=cd2c/1/0x4000000000000000 softirq=64081/64081 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=81341, q=406 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14534 Comm: syz.1.2576 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:65
Code: 48 89 da e8 02 62 f4 ff 48 8b 74 24 30 48 c7 c7 e0 51 1d 8b e8 f1 61 f4 ff e8 cc 7f ff ff eb a8 e8 75 e8 ff ff 0f 1f 44 00 00 <f3> 0f 1e fa 48 89 fe 48 c7 c7 60 51 1d 8b e9 dd fe ff ff cc cc cc
RSP: 0018:ffffc90000007b98 EFLAGS: 00000096
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8168b2a1
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8acae160
RBP: ffffc90000007ca8 R08: dffffc0000000000 R09: 1ffffffff23fe2a1
R10: dffffc0000000000 R11: fffffbfff23fe2a2 R12: 1ffff92000000f80
R13: ffff8880b8c2b758 R14: 0000000000000046 R15: dffffc0000000000
FS:  00007f6e390c46c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e390c3ff8 CR3: 0000000067e9f000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
 lock_acquire+0x1ae/0x420 kernel/locking/lockdep.c:5792
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xaf/0xf0 kernel/locking/spinlock.c:170
 __run_hrtimer kernel/time/hrtimer.c:1758 [inline]
 __hrtimer_run_queues+0x5da/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:ffffc900040ff900 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 0e19bf380f0c6f00
RDX: dffffc0000000000 RSI: ffffffff8acacfe0 RDI: 0000000000000001
RBP: ffffc900040ff990 R08: ffffffff91ff1507 R09: 1ffffffff23fe2a0
R10: dffffc0000000000 R11: fffffbfff23fe2a1 R12: dffffc0000000000
R13: ffff8880b8c2b740 R14: ffff8880b8c2b740 R15: 1ffff9200081ff20
 clock_was_set+0x689/0x800 kernel/time/hrtimer.c:986
 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: 0033:0x7f6e3819f559
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:00007f6e390c4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000131
RAX: ffffffffffffffda RBX: 00007f6e38425fa0 RCX: 00007f6e3819f559
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007f6e38236b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e38426038 R14: 00007f6e38425fa0 R15: 00007ffe4b24e638
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g81341 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=37961
rcu: rcu_preempt kthread starved for 10502 jiffies! g81341 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:26504 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 14534 Comm: syz.1.2576 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:check_region_inline mm/kasan/generic.c:-1 [inline]
RIP: 0010:kasan_check_range+0x14/0x290 mm/kasan/generic.c:187
Code: b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 cc cc cc cc cc cc cc cc 66 0f 1f 00 b0 01 48 85 f6 0f 84 b4 01 00 00 55 41 57 41 56 <41> 55 41 54 53 4c 8d 04 37 49 39 f8 0f 82 13 02 00 00 49 89 f9 49
RSP: 0018:ffffc90000007b40 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff816899c7
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8f6c5ae8
RBP: ffffc90000007c80 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100f9e145e R12: 1ffff92000000f78
R13: ffffffff8df320e0 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f6e390c46c0(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6e390c3ff8 CR3: 0000000067e9f000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:504 [inline]
 cpu_online include/linux/cpumask.h:1082 [inline]
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0xb7/0x420 kernel/locking/lockdep.c:5761
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 advance_sched+0x9f3/0xc70 net/sched/sch_taprio.c:1002
 __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:ffffc900040ff900 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 0e19bf380f0c6f00
RDX: dffffc0000000000 RSI: ffffffff8acacfe0 RDI: 0000000000000001
RBP: ffffc900040ff990 R08: ffffffff91ff1507 R09: 1ffffffff23fe2a0
R10: dffffc0000000000 R11: fffffbfff23fe2a1 R12: dffffc0000000000
R13: ffff8880b8c2b740 R14: ffff8880b8c2b740 R15: 1ffff9200081ff20
 clock_was_set+0x689/0x800 kernel/time/hrtimer.c:986
 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: 0033:0x7f6e3819f559
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:00007f6e390c4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000131
RAX: ffffffffffffffda RBX: 00007f6e38425fa0 RCX: 00007f6e3819f559
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000000
RBP: 00007f6e38236b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6e38426038 R14: 00007f6e38425fa0 R15: 00007ffe4b24e638
 </TASK>

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/20 23:54 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
2026/10/20 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.