syzbot


INFO: rcu detected stall in nsim_fib_event_work

Status: upstream: reported syz repro on 2024/09/01 09:18
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+e5beaea4288bdc45b1fe@syzkaller.appspotmail.com
First crash: 314d, last: 13d
Bug presence (3)
Date Name Commit Repro Result
2024/10/16 linux-5.15.y (ToT) 3a5928702e71 C [report] INFO: rcu detected stall in corrupted
2024/09/01 upstream (ToT) 431c1646e1f8 C [report] BUG: workqueue lockup
2024/10/16 upstream (ToT) c964ced77262 C Didn't crash
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in nsim_fib_event_work 1 1 396d 396d 0/3 auto-obsoleted due to no activity on 2024/09/19 04:15
linux-6.1 INFO: rcu detected stall in nsim_fib_event_work (2) 1 1 279d 279d 0/3 auto-obsoleted due to no activity on 2025/01/14 20:10
linux-6.1 INFO: rcu detected stall in nsim_fib_event_work (3) origin:lts-only 1 syz error 3 21d 118d 0/3 upstream: reported syz repro on 2025/03/16 03:46
upstream INFO: rcu detected stall in nsim_fib_event_work mm 1 C error 3 18d 72d 0/29 upstream: reported C repro on 2025/05/01 18:02
Last patch testing requests (9)
Created Duration User Patch Repo Result
2025/05/30 03:01 13m retest repro linux-5.15.y report log
2025/05/30 03:01 14m retest repro linux-5.15.y report log
2025/05/27 11:41 13m retest repro linux-5.15.y report log
2025/05/27 11:41 13m retest repro linux-5.15.y report log
2025/03/20 07:12 1h12m retest repro linux-5.15.y report log
2025/03/20 07:12 13m retest repro linux-5.15.y report log
2025/03/05 01:32 14m retest repro linux-5.15.y report log
2024/12/27 09:05 16m retest repro linux-5.15.y report log
2024/12/27 09:05 15m retest repro linux-5.15.y report log
Fix bisection attempts (4)
Created Duration User Patch Repo Result
2025/06/18 11:47 1h38m fix candidate upstream error job log
2025/05/06 17:59 1h14m fix candidate upstream error job log
2025/01/19 16:50 5m fix candidate upstream error job log
2024/10/26 09:57 5m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4129/1:b..l
	(detected by 1, t=10502 jiffies, g=7017, q=191)
task:kworker/0:12    state:R  running task     stack:    0 pid: 4129 ppid:     2 flags:0x00000008
Workqueue: events nsim_fib_event_work
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0xe00/0x1c0c kernel/sched/core.c:6376
 preempt_schedule_irq+0x90/0x214 kernel/sched/core.c:6780
 arm64_preempt_schedule_irq+0x14c/0x21c arch/arm64/kernel/entry-common.c:260
 el1_interrupt+0x40/0x58 arch/arm64/kernel/entry-common.c:463
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470
 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522
 arch_local_irq_enable arch/arm64/include/asm/irqflags.h:35 [inline]
 __local_bh_enable_ip+0x200/0x380 kernel/softirq.c:406
 local_bh_enable+0x28/0x34 include/linux/bottom_half.h:32
 rht_assign_unlock+0xa0/0xc0 include/linux/rhashtable.h:404
 __rhashtable_insert_fast include/linux/rhashtable.h:788 [inline]
 rhashtable_insert_fast+0x570/0xb70 include/linux/rhashtable.h:825
 nsim_fib6_rt_add drivers/net/netdevsim/fib.c:684 [inline]
 nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:757 [inline]
 nsim_fib6_event drivers/net/netdevsim/fib.c:854 [inline]
 nsim_fib_event drivers/net/netdevsim/fib.c:887 [inline]
 nsim_fib_event_work+0x1798/0x2704 drivers/net/netdevsim/fib.c:1483
 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310
 process_scheduled_works kernel/workqueue.c:2373 [inline]
 worker_thread+0xb64/0x101c kernel/workqueue.c:2459
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855
rcu: rcu_preempt kthread starved for 10503 jiffies! g7017 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:    0 pid:   15 ppid:     2 flags:0x00000008
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0xe00/0x1c0c kernel/sched/core.c:6376
 schedule+0x11c/0x1c8 kernel/sched/core.c:6459
 schedule_timeout+0x180/0x2c8 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x25c/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xc4/0x2a8 kernel/rcu/tree.c:2145
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 0:
task:syz.1.77        state:R  running task     stack:    0 pid: 4356 ppid:  4142 flags:0x00000001
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 0xffff0000d377b680

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/29 10:26 linux-5.15.y 3dea0e7f549e fc9d8ee5 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in nsim_fib_event_work
2025/05/11 19:44 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in nsim_fib_event_work
2025/03/05 01:32 linux-5.15.y c16c81c81336 c3901742 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in nsim_fib_event_work
2024/09/19 00:13 linux-5.15.y 3a5928702e71 c673ca06 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in nsim_fib_event_work
2024/09/01 09:17 linux-5.15.y fa93fa65db6e 1eda0d14 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in nsim_fib_event_work
* Struck through repros no longer work on HEAD.