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: 99d, last: 2d07h
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 127d 1014d 0/29 upstream: reported C repro on 2023/08/17 09:25
linux-6.1 INFO: rcu detected stall in clock_nanosleep 1 6 55d 157d 0/3 upstream: reported on 2025/12/21 12:05
linux-5.15 INFO: rcu detected stall in sys_clock_nanosleep (3) 1 6 227d 490d 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 989d 989d 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 713d 868d 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 1337d 1458d 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 1635d 1645d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_clock_nanosleep kernel 1 1 1890d 1890d 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 1165d 1165d 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 1768d 1768d 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 792d 865d 0/3 auto-obsoleted due to no activity on 2024/07/04 20:17
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/05/06 06:42 19m retest repro linux-5.15.y report log
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/04/25 02:52 15m fix candidate upstream error job log
2026/03/20 08:31 1m fix candidate upstream error job log
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-....: (0 ticks this GP) idle=9a5/1/0x4000000000000002 softirq=7200/7200 fqs=5249 
	(detected by 1, t=10502 jiffies, g=7305, q=1492)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4561 Comm: syz.3.50 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:85 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x84/0x290 mm/kasan/generic.c:189
Code: 49 c1 e9 03 4b 8d 1c 21 49 89 df 4d 29 df 49 83 ff 10 7f 29 4d 85 ff 0f 84 38 01 00 00 4c 89 cb 48 f7 d3 4c 01 f3 41 80 3b 00 <0f> 85 86 01 00 00 49 ff c3 48 ff c3 75 ee e9 18 01 00 00 44 89 dd
RSP: 0018:ffffc90000007370 EFLAGS: 00000046
RAX: ffffffff81981901 RBX: fffffffffffffffc RCX: ffffffff81981992
RDX: 0000000000000001 RSI: 0000000000000038 RDI: ffffc90000007400
RBP: 0000000000000000 R08: ffffc90000007437 R09: 1ffff92000000e86
R10: dffffc0000000000 R11: fffff52000000e83 R12: dffffc0000000001
R13: 1ffff92000000e7c R14: 1ffff92000000e80 R15: 0000000000000007
FS:  000055558b5a2500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffbef7f2158 CR3: 000000001b7f9000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 memset+0x1e/0x40 mm/kasan/shadow.c:44
 __perf_event_output kernel/events/core.c:7795 [inline]
 perf_event_output_forward+0x172/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 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 d2 df 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:ffffc90000007a00 EFLAGS: 00000206
RAX: 956c9c9ab989e000 RBX: 1ffff92000000f44 RCX: 956c9c9ab989e000
RDX: dffffc0000000000 RSI: ffffffff8a2b3100 RDI: ffffffff8a7a0700
RBP: ffffc90000007ae0 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: ffffffff8c323800
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]
 process_backlog+0x3ef/0x790 net/core/dev.c:6543
 __napi_poll+0xc0/0x430 net/core/dev.c:7101
 napi_poll net/core/dev.c:7168 [inline]
 net_rx_action+0x4d4/0xa10 net/core/dev.c:7258
 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 dc 60 68 08 85 c0 74 4a 4d 85 ff 75 66 0f 1f 44 00 00 48 89 df e8 86 cc 71 08 e8 81 e6 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:ffffc90004a4f948 EFLAGS: 00000286
RAX: 956c9c9ab989e000 RBX: ffff8880b903a340 RCX: 956c9c9ab989e000
RDX: dffffc0000000000 RSI: ffffffff8a2b3100 RDI: ffffffff8a7a0700
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: 0033:0x7f6e495a568e
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:00007ffdcdad4608 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 000055558b5a2500 RCX: 00007f6e495a568e
RDX: 00007ffdcdad4660 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f6e4985fda0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000004fa2b
R13: 00007f6e4985e09c R14: 000000000004f751 R15: 00007f6e4985e090
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/25 16:00 linux-5.15.y 241d66fa280c c69befb3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in clock_nanosleep
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
2026/03/02 22:11 linux-5.15.y 3330a8d33e08 b9dd6534 .config console log report info [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.