syzbot


INFO: rcu detected stall in clock_nanosleep

Status: upstream: reported syz repro on 2026/02/17 07:30
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+c81d16ad684073fabd5d@syzkaller.appspotmail.com
First crash: 1d21h, last: 1d21h
Bug presence (2)
Date Name Commit Repro Result
2026/02/17 linux-5.15.y (ToT) e45d5d41c134 syz [report] INFO: rcu detected stall in corrupted
2026/02/17 upstream (ToT) 970296997869 syz Didn't crash
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_clock_nanosleep (5) kernel 1 C error done 105 29d 916d 0/29 upstream: reported C repro on 2023/08/17 09:25
linux-6.1 INFO: rcu detected stall in clock_nanosleep 1 3 10d 59d 0/3 upstream: reported on 2025/12/21 12:05
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep (3) 1 6 129d 392d 0/3 auto-obsoleted due to no activity on 2026/01/20 16:04
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep 1 1 891d 891d 0/3 auto-obsoleted due to no activity on 2023/12/20 18:13
linux-6.1 INFO: rcu detected stall in sys_clock_nanosleep (2) 1 4 615d 770d 0/3 auto-obsoleted due to no activity on 2024/09/21 09:26
upstream INFO: rcu detected stall in sys_clock_nanosleep (4) kernel 1 6 1240d 1360d 0/29 auto-obsoleted due to no activity on 2022/12/31 21:43
upstream INFO: rcu detected stall in sys_clock_nanosleep (3) kernel 1 3 1537d 1547d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_clock_nanosleep kernel 1 1 1792d 1792d 0/29 auto-closed as invalid on 2021/06/22 18:23
linux-6.1 INFO: rcu detected stall in sys_clock_nanosleep 1 1 1067d 1067d 0/3 auto-obsoleted due to no activity on 2023/07/17 12:13
upstream INFO: rcu detected stall in sys_clock_nanosleep (2) kernel 1 1 1670d 1670d 0/29 auto-closed as invalid on 2021/10/22 22:53
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep (2) 1 2 694d 767d 0/3 auto-obsoleted due to no activity on 2024/07/04 20:17
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/02/17 15:01 1m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 ticks this GP) idle=999/1/0x4000000000000002 softirq=7180/7180 fqs=2100 
	(detected by 1, t=10503 jiffies, g=6825, q=1085)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4329 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__lock_release kernel/locking/lockdep.c:5311 [inline]
RIP: 0010:lock_release+0x242/0x8a0 kernel/locking/lockdep.c:5643
Code: 8d 74 24 24 4c 89 f0 48 c1 e8 03 42 0f b6 04 28 84 c0 0f 85 a7 04 00 00 41 83 3e 00 0f 85 dd 03 00 00 4d 8d 74 24 20 4c 89 f3 <48> c1 eb 03 42 0f b6 04 2b 84 c0 4c 8b 7c 24 20 0f 85 a3 04 00 00
RSP: 0018:ffffc90000007000 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff88802a172920 RCX: 0000000000000001
RDX: 0000000000000002 RSI: ffffffff8c31eaa0 RDI: ffff88802a172900
RBP: ffffc90000007110 R08: ffffffff8d89db2f R09: 1ffffffff1b13b65
R10: dffffc0000000000 R11: fffffbfff1b13b66 R12: ffff88802a172900
R13: dffffc0000000000 R14: ffff88802a172920 R15: 0000000000000002
FS:  0000555584e11500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33263fff CR3: 000000001f61d000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_read_unlock include/linux/rcupdate.h:773 [inline]
 __perf_event_output kernel/events/core.c:7813 [inline]
 perf_event_output_forward+0x261/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_swevent_overflow kernel/events/core.c:9591 [inline]
 perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9629
 perf_tp_event+0x383/0xbf0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 e2 f0 9c 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900000077c0 EFLAGS: 00000206
RAX: 5272ae83816e0500 RBX: 1ffff92000000efc RCX: 5272ae83816e0500
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f740
RBP: ffffc900000078a0 R08: ffffffff901d21e7 R09: 1ffffffff203a43c
R10: dffffc0000000000 R11: fffffbfff203a43d R12: ffffffff8c322f00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 ndisc_send_skb+0xde0/0x1500 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x2d1/0x630 net/ipv6/addrconf.c:3956
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x339/0x830 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+0x134/0x280 kernel/sched/core.c:4804
Code: be ff ff ff ff e8 6c b1 67 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 16 1d 71 08 e8 21 e4 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 c9 09 fe ff 43 80 3c
RSP: 0018:ffffc90002fff948 EFLAGS: 00000286
RAX: 5272ae83816e0500 RBX: ffff8880b903a340 RCX: 5272ae83816e0500
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f740
RBP: 1ffff11017207613 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11f7/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 freezable_schedule include/linux/freezer.h:172 [inline]
 do_nanosleep+0x1f1/0x770 kernel/time/hrtimer.c:2026
 hrtimer_nanosleep+0x33e/0x590 kernel/time/hrtimer.c:2079
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1314 [inline]
 __se_sys_clock_nanosleep+0x30b/0x3a0 kernel/time/posix-timers.c:1291
 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: 0033:0x7f664e77f84e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffeda15d328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 0000555584e11500 RCX: 00007f664e77f84e
RDX: 00007ffeda15d380 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffeda15d3ec R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000001388
R13: 00000000000927c0 R14: 000000000002a9d9 R15: 00007ffeda15d440
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/17 07:30 linux-5.15.y e45d5d41c134 e439b951 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in clock_nanosleep
* Struck through repros no longer work on HEAD.