syzbot

 sign-in | mailing list | source | docs
🐞 Open [1586]
≡ Subsystems
🐞 Fixed [6359]
🐞 Invalid [16222]
⬇ Missing Backports [194]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

INFO: rcu detected stall in wait4 (2)

Status: auto-obsoleted due to no activity on 2022/10/24 16:24
Subsystems: kernel
[Documentation on labels]
First crash: 1159d, last: 1077d
▶ ▼ Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in wait4 (3) kernel 2 875d 880d 0/29 auto-obsoleted due to no activity on 2023/05/14 12:43
upstream INFO: rcu detected stall in wait4 kernel 2 1493d 1549d 0/29 auto-closed as invalid on 2021/09/04 10:15
upstream INFO: rcu detected stall in wait4 (5) fs 6 249d 280d 0/29 auto-obsoleted due to no activity on 2025/01/30 05:34
upstream INFO: rcu detected stall in wait4 (4) kernel C error done 35 392d 721d 0/29 auto-obsoleted due to no activity on 2024/09/18 16:22
upstream INFO: rcu detected stall in wait4 (6) kernel 1 130d 130d 0/29 auto-obsoleted due to no activity on 2025/05/29 01:55

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=885/1/0x4000000000000000 softirq=49214/49216 fqs=9 
	(detected by 1, t=10502 jiffies, g=78705, q=365 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3652 Comm: syz-executor.5 Not tainted 5.19.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
RIP: 0010:div64_u64 include/linux/math64.h:69 [inline]
RIP: 0010:taprio_set_budget net/sched/sch_taprio.c:554 [inline]
RIP: 0010:advance_sched+0x3ce/0x9a0 net/sched/sch_taprio.c:760
Code: 38 d0 7c 08 84 d2 0f 85 5d 05 00 00 41 8b 44 24 2c 4d 8d 74 24 20 31 d2 be 04 00 00 00 4c 89 f7 48 69 c0 e8 03 00 00 48 f7 f5 <48> 89 c5 e8 ea bc 3c fa 4c 89 f2 48 b8 00 00 00 00 00 fc ff df 48
RSP: 0018:ffffc90000007dd0 EFLAGS: 00000006
RAX: 0000000140000002 RBX: ffff8880793ce340 RCX: ffff888021b8feac
RDX: 00000000000000c8 RSI: 0000000000000004 RDI: ffff888021b8fea0
RBP: 0000000000000190 R08: 0000000000000000 R09: ffff8880793ce2e7
R10: ffffed100f279c5c R11: 0000000000000001 R12: ffff888021b8fe80
R13: 17cd431baf9a8637 R14: ffff888021b8fea0 R15: 17cd431baf9a8637
FS:  0000555556f9c400(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0d7b9a0000 CR3: 0000000030188000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1112
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1106
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:__raw_write_unlock_irq include/linux/rwlock_api_smp.h:274 [inline]
RIP: 0010:_raw_write_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:358
Code: 0f 1f 44 00 00 55 48 8b 74 24 08 48 89 fd 48 83 c7 18 e8 1e 13 e3 f7 48 89 ef e8 e6 9b e3 f7 e8 81 80 05 f8 fb bf 01 00 00 00 <e8> a6 9c d6 f7 65 8b 05 4f 03 88 76 85 c0 74 02 5d c3 e8 9b d9 85
RSP: 0018:ffffc900037e7a38 EFLAGS: 00000202
RAX: 0000000000611c43 RBX: ffff8880745d00c0 RCX: 1ffffffff1b75cf9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffffff8ba0a080 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88801c1d0b10
R13: ffff8880745d00c0 R14: dffffc0000000000 R15: ffff88801c1d0b00
 release_task+0xca3/0x17e0 kernel/exit.c:224
 wait_task_zombie kernel/exit.c:1111 [inline]
 wait_consider_task+0x2fda/0x3bf0 kernel/exit.c:1338
 do_wait_thread kernel/exit.c:1401 [inline]
 do_wait+0x6ca/0xce0 kernel/exit.c:1518
 kernel_wait4+0x14c/0x260 kernel/exit.c:1681
 __do_sys_wait4+0x13f/0x150 kernel/exit.c:1709
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd95ba876a7
Code: 89 7c 24 10 48 89 4c 24 18 e8 35 50 02 00 4c 8b 54 24 18 8b 54 24 14 41 89 c0 48 8b 74 24 08 8b 7c 24 10 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 89 44 24 10 e8 65 50 02 00 8b 44
RSP: 002b:00007ffc6f669af0 EFLAGS: 00000293 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 00000000000007eb RCX: 00007fd95ba876a7
RDX: 0000000040000001 RSI: 00007ffc6f669b7c RDI: 00000000ffffffff
RBP: 00007ffc6f669b7c R08: 0000000000000000 R09: 00007ffc6f7f0080
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032
R13: 00000000000ab1cf R14: 000000000000000e R15: 00007ffc6f669be0
 </TASK>
rcu: rcu_preempt kthread starved for 10484 jiffies! g78705 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:28864 pid:   16 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5146 [inline]
 __schedule+0xa00/0x4b50 kernel/sched/core.c:6458
 schedule+0xd2/0x1f0 kernel/sched/core.c:6530
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1935
 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1999
 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2187
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 7108 Comm: kworker/u4:14 Not tainted 5.19.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: events_unbound toggle_allocation_gate
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1e6/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:518
 print_other_cpu_stall kernel/rcu/tree_stall.h:623 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:769 [inline]
 rcu_pending kernel/rcu/tree.c:3977 [inline]
 rcu_sched_clock_irq+0x2311/0x2370 kernel/rcu/tree.c:2675
 update_process_times+0x11a/0x1a0 kernel/time/timer.c:1839
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:243
 tick_sched_timer+0xee/0x120 kernel/time/tick-sched.c:1480
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1112
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1106
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:csd_lock_wait kernel/smp.c:414 [inline]
RIP: 0010:smp_call_function_many_cond+0x499/0x1110 kernel/smp.c:988
Code: 01 89 ee e8 49 98 0a 00 85 ed 74 47 48 8b 04 24 49 89 c4 83 e0 07 49 c1 ec 03 48 89 c5 4d 01 fc 83 c5 03 e8 e9 9b 0a 00 f3 90 <41> 0f b6 04 24 40 38 c5 7c 08 84 c0 0f 85 21 0a 00 00 8b 43 08 31
RSP: 0018:ffffc90004f8f950 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffffe8ffffc0bd20 RCX: 0000000000000000
RDX: ffff88803d004240 RSI: ffffffff816f0127 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: fffff91ffff817a5
R13: 0000000000000000 R14: 0000000000000001 R15: dffffc0000000000
 on_each_cpu_cond_mask+0x56/0xa0 kernel/smp.c:1154
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1302 [inline]
 text_poke_bp_batch+0x233/0x6c0 arch/x86/kernel/alternative.c:1490
 text_poke_flush arch/x86/kernel/alternative.c:1660 [inline]
 text_poke_flush arch/x86/kernel/alternative.c:1657 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1667
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x32f/0x410 kernel/jump_label.c:830
 static_key_enable_cpuslocked+0x1b1/0x260 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 toggle_allocation_gate mm/kfence/core.c:811 [inline]
 toggle_allocation_gate+0x100/0x390 mm/kfence/core.c:803
 process_one_work+0x996/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
vkms_vblank_simulate: vblank timer overrun

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/07/26 16:17 upstream e0dccc3b76fb 34795c51 .config console log report info ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in wait4
2022/05/06 03:38 upstream fe27d189e3f4 efeff0a5 .config console log report info ci-upstream-kasan-gce-root INFO: rcu detected stall in wait4
* Struck through repros no longer work on HEAD.