syzbot


INFO: rcu detected stall in clock_nanosleep

Status: upstream: reported on 2025/12/21 12:05
Reported-by: syzbot+7f2ffeff791dbe94e0a7@syzkaller.appspotmail.com
First crash: 96d, last: 5d00h
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 66d 953d 0/29 upstream: reported C repro on 2023/08/17 09:25
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep (3) 1 6 166d 429d 0/3 auto-obsoleted due to no activity on 2026/01/20 16:04
linux-5.15 INFO: rcu detected stall in clock_nanosleep origin:lts-only 1 syz error 2 25d 38d 0/3 upstream: reported syz repro on 2026/02/17 07:30
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep 1 1 928d 928d 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 652d 807d 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 1277d 1397d 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 1574d 1584d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_clock_nanosleep kernel 1 1 1829d 1829d 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 1104d 1104d 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 1707d 1707d 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 731d 804d 0/3 auto-obsoleted due to no activity on 2024/07/04 20:17

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2675 jiffies s: 20149 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7810 Comm: syz.2.962 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
RIP: 0010:rcu_is_watching+0x36/0xa0 kernel/rcu/tree.c:721
Code: e8 4f aa c0 08 89 c3 83 f8 08 73 60 49 bf 00 00 00 00 00 fc ff df 4c 8d 34 dd 80 09 65 8c 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 <74> 08 4c 89 f7 e8 b0 ed 66 00 48 c7 c3 08 58 03 00 49 03 1e 48 89
RSP: 0018:ffffc900001e0460 EFLAGS: 00000046
RAX: 1ffffffff18ca131 RBX: 0000000000000001 RCX: d564bac16267dd00
RDX: 0000000000000000 RSI: ffffffff8adf0f40 RDI: ffffffff8adf0f00
RBP: 0000000000000000 R08: ffffffff8e1fd76f R09: 1ffffffff1c3faed
R10: dffffc0000000000 R11: fffffbfff1c3faee R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8c650988 R15: dffffc0000000000
FS:  000055558c6f8500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f786392b9c0 CR3: 0000000018aa1000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 trace_irq_work_entry arch/x86/include/asm/trace/irq_vectors.h:64 [inline]
 __sysvec_irq_work+0xaa/0x350 arch/x86/kernel/irq_work.c:20
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x4a/0xc0 arch/x86/kernel/irq_work.c:17
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
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 33 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900001e0560 EFLAGS: 00000206
RAX: d564bac16267dd00 RBX: 1ffff9200003c0b4 RCX: d564bac16267dd00
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0f60
RBP: ffffc900001e0660 R08: ffffffff90af634f R09: 1ffffffff215ec69
R10: dffffc0000000000 R11: fffffbfff215ec6a R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 __icmp_send+0x612/0x1410 net/ipv4/icmp.c:803
 ipv4_send_dest_unreach net/ipv4/route.c:1263 [inline]
 ipv4_link_failure+0x667/0xa20 net/ipv4/route.c:1270
 dst_link_failure include/net/dst.h:423 [inline]
 arp_error_report+0x10e/0x160 net/ipv4/arp.c:296
 neigh_invalidate+0x22c/0x450 net/core/neighbour.c:1064
 neigh_timer_handler+0x911/0x1080 net/core/neighbour.c:1151
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/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> 0f cc 21 f7 65 8b 05 d0 50 cb 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc900034bfca0 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: d564bac16267dd00
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: 0000000000000001
RBP: ffffc900034bfd30 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: dffffc0000000000
R13: ffffc900034bfd80 R14: ffffffff96eadea8 R15: 1ffff92000697f94
 hrtimer_init_sleeper_on_stack kernel/time/hrtimer.c:473 [inline]
 hrtimer_nanosleep+0xbe/0x370 kernel/time/hrtimer.c:2134
 __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:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7a8ef5cfce
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:00007fffd0319168 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 000055558c6f8500 RCX: 00007f7a8ef5cfce
RDX: 00007fffd03191c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f7a8f217da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000038f29
R13: 00007f7a8f21609c R14: 0000000000038e7e R15: 00007f7a8f216090
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/23 06:20 linux-6.1.y f2ddafa93a25 5b92003d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in clock_nanosleep
2026/03/20 09:01 linux-6.1.y f2ddafa93a25 2f245add .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in clock_nanosleep
2026/02/09 02:10 linux-6.1.y 0182cb5b74ee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in clock_nanosleep
2026/02/03 17:23 linux-6.1.y cd9b81672742 6df4c87a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in clock_nanosleep
2025/12/21 12:04 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in clock_nanosleep
* Struck through repros no longer work on HEAD.