syzbot

 sign-in | mailing list | source | docs
🐞 Open [1457]
≡ Subsystems
🐞 Fixed [6857]
🐞 Invalid [17791]
⬇ Missing Backports [225]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

INFO: rcu detected stall in sys_timerfd_settime (6)

Status: auto-obsoleted due to no activity on 2025/11/21 04:18
Subsystems: fs
[Documentation on labels]
First crash: 114d, last: 114d
▶ ▼ Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in sys_timerfd_settime (2) 1 3 526d 566d 0/3 auto-obsoleted due to no activity on 2024/11/14 05:49
upstream INFO: rcu detected stall in sys_timerfd_settime fs 1 3 1524d 1591d 0/29 closed as invalid on 2022/02/08 09:50
upstream INFO: rcu detected stall in sys_timerfd_settime (4) fs 1 1 641d 641d 0/29 auto-obsoleted due to no activity on 2024/06/12 13:14
upstream INFO: rcu detected stall in sys_timerfd_settime (2) net 1 1 1093d 1093d 0/29 auto-obsoleted due to no activity on 2023/04/25 06:19
linux-6.1 INFO: rcu detected stall in sys_timerfd_settime (3) 1 3 138d 273d 0/3 auto-obsoleted due to no activity on 2025/12/06 18:33
linux-5.15 INFO: rcu detected stall in sys_timerfd_settime (4) 1 5 159d 222d 0/3 auto-obsoleted due to no activity on 2025/11/16 15:42
upstream INFO: rcu detected stall in sys_timerfd_settime (3) fs 1 2 735d 788d 0/29 auto-obsoleted due to no activity on 2024/04/09 00:01
upstream INFO: rcu detected stall in sys_timerfd_settime (5) fs 1 17 340d 545d 0/29 auto-obsoleted due to no activity on 2025/05/09 08:53
linux-5.15 INFO: rcu detected stall in sys_timerfd_settime 1 1 945d 945d 0/3 auto-obsoleted due to no activity on 2023/09/22 02:06
linux-6.1 INFO: rcu detected stall in sys_timerfd_settime 1 1 937d 937d 0/3 auto-obsoleted due to no activity on 2023/09/29 23:03
linux-5.15 INFO: rcu detected stall in sys_timerfd_settime (3) 1 1 419d 419d 0/3 auto-obsoleted due to no activity on 2025/03/01 03:09
linux-6.1 INFO: rcu detected stall in sys_timerfd_settime (2) 1 1 391d 391d 0/3 auto-obsoleted due to no activity on 2025/03/29 01:59

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=879c/1/0x4000000000000000 softirq=60025/60025 fqs=10
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11815/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=52929, q=164 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 11817 Comm: syz.3.1503 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:124 [inline]
RIP: 0010:lock_acquire+0xb2/0x360 kernel/locking/lockdep.c:5844
Code: e8 63 d1 86 00 83 3d 7c 4d 26 0e 00 0f 84 fa 00 00 00 65 8b 05 6f 57 26 11 85 c0 0f 85 eb 00 00 00 65 48 8b 04 25 08 90 c3 92 <83> b8 2c 0b 00 00 00 0f 85 d5 00 00 00 48 c7 44 24 30 00 00 00 00
RSP: 0018:ffffc90000a08bc0 EFLAGS: 00000046
RAX: ffff8880636c5ac0 RBX: 0000000000000000 RCX: c4f7c2a2b4079a00
RDX: 0000000000000000 RSI: ffffffff8b8773be RDI: 1ffff1100a83e260
RBP: ffffffff89a337c4 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff89a33700 R12: 0000000000000000
R13: ffff8880541f1300 R14: 0000000000000000 R15: 0000000000000001
FS:  00007f3d28b366c0(0000) GS:ffff888125ae7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3d25ff5f98 CR3: 000000005b838000 CR4: 00000000003526f0
DR0: 0000000000000008 DR1: 0000000000000002 DR2: 0000000000000081
DR3: ffffffffefffff14 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 advance_sched+0xc4/0xc90 net/sched/sch_taprio.c:929
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x52c/0xc60 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ba 11 16 f6 48 89 df e8 12 a9 16 f6 e8 2d 0b 40 f6 fb bf 01 00 00 00 <e8> f2 9f 08 f6 65 8b 05 3b 18 3c 07 85 c0 74 07 5b c3 cc cc cc cc
RSP: 0018:ffffc900041cfce8 EFLAGS: 00000282
RAX: c4f7c2a2b4079a00 RBX: ffff88805adf4488 RCX: c4f7c2a2b4079a00
RDX: 0000000000000000 RSI: ffffffff8dba2d53 RDI: 0000000000000001
RBP: 7fffffffffffffff R08: ffffffff8fc39677 R09: 1ffffffff1f872ce
R10: dffffc0000000000 R11: fffffbfff1f872cf R12: ffff88805adf4488
R13: dffffc0000000000 R14: ffff88803370b500 R15: 7fffffffffffffff
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 do_timerfd_settime+0xd4c/0xf90 fs/timerfd.c:522
 __do_sys_timerfd_settime fs/timerfd.c:568 [inline]
 __se_sys_timerfd_settime fs/timerfd.c:559 [inline]
 __x64_sys_timerfd_settime+0x161/0x220 fs/timerfd.c:559
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3d27d8ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3d28b36038 EFLAGS: 00000246 ORIG_RAX: 000000000000011e
RAX: ffffffffffffffda RBX: 00007f3d27fd5fa0 RCX: 00007f3d27d8ec29
RDX: 0000200000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 00007f3d27e11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3d27fd6038 R14: 00007f3d27fd5fa0 R15: 00007ffc01b0a908
 </TASK>
task:syz.6.1502      state:R  running task     stack:25960 pid:11815 tgid:11813 ppid:10548  task_flags:0x400140 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7291
 irqentry_exit+0x6f/0x90 kernel/entry/common.c:211
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:104 [inline]
RIP: 0010:__local_bh_enable_ip+0x135/0x1c0 kernel/softirq.c:457
Code: 8b e8 4f 13 00 0a 65 66 8b 05 1f a7 3e 11 66 85 c0 75 5a bf 01 00 00 00 e8 b8 2e 0b 00 e8 e3 99 42 00 fb 65 8b 05 fb a6 3e 11 <85> c0 75 05 e8 e2 ee ae ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc9000422f920 EFLAGS: 00000282
RAX: 0000000080000000 RBX: 0000000000000200 RCX: 945dd45540bdf400
RDX: 0000000000000000 RSI: ffffffff8dba2d53 RDI: ffffffff8c03aa60
RBP: ffffc9000422f9b0 R08: ffffffff8fc39677 R09: 1ffffffff1f872ce
R10: dffffc0000000000 R11: fffffbfff1f872cf R12: ffffffff89aba2d7
R13: ffffc90002f30030 R14: dffffc0000000000 R15: 1ffff92000845f24
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 bpf_test_run+0x376/0x7b0 net/bpf/test_run.c:437
 bpf_prog_test_run_skb+0xb30/0x1560 net/bpf/test_run.c:1099
 bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4590
 __sys_bpf+0x581/0x870 kernel/bpf/syscall.c:6047
 __do_sys_bpf kernel/bpf/syscall.c:6139 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6137 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6137
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f98ed58ec29
RSP: 002b:00007f98ee366038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f98ed7d6090 RCX: 00007f98ed58ec29
RDX: 0000000000000050 RSI: 0000200000000600 RDI: 000000000000000a
RBP: 00007f98ed611e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f98ed7d6128 R14: 00007f98ed7d6090 R15: 00007ffc6388b078
 </TASK>
rcu: rcu_preempt kthread starved for 10482 jiffies! g52929 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:26464 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7046 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7061
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 6502 Comm: kworker/u8:19 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd44/0x12d0 kernel/smp.c:877
Code: 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 e1 74 0b 00 eb 38 f3 90 42 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 <74> 1e e8 c5 74 0b 00 eb e4 44 89 e1 80 e1 07 80 c1 03 38 c1 7c e2
RSP: 0018:ffffc9000b367640 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 1ffff110170e7ffd RCX: ffff88801eb70000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000b3677c0 R08: ffffffff8fc39677 R09: 1ffffffff1f872ce
R10: dffffc0000000000 R11: fffffbfff1f872cf R12: ffff8880b873ffe8
R13: dffffc0000000000 R14: ffff8880b863b200 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881259e7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000000e138000 CR4: 00000000003526f0
DR0: 0000000000000008 DR1: 0000000000000002 DR2: 0000000000000081
DR3: ffffffffefffff14 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043
 on_each_cpu include/linux/smp.h:71 [inline]
 smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2713 [inline]
 smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2923
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210
 static_key_enable+0x1a/0x20 kernel/jump_label.c:223
 toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:852
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/22 04:11 linux-next 846bd2225ec3 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: rcu detected stall in sys_timerfd_settime
* Struck through repros no longer work on HEAD.