INFO: rcu detected stall in nsim_dev_trap_report_work (3)

Status: upstream: reported C repro on 2025/08/20 06:57
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+adf3d9d216d554ccac29@syzkaller.appspotmail.com
First crash: 386d, last: 4d03h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/12/08 linux-5.15.y (ToT) 68efe5a6c16a C [report] INFO: rcu detected stall in corrupted
2025/12/08 upstream (ToT) c2f2b01b74be C Didn't crash
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in nsim_dev_trap_report_work 1 2 796d 819d 0/3 auto-obsoleted due to no activity on 2024/10/13 18:52
linux-5.15 INFO: rcu detected stall in nsim_dev_trap_report_work (2) 1 1 583d 583d 0/3 auto-obsoleted due to no activity on 2025/05/14 15:54
upstream INFO: rcu detected stall in nsim_dev_trap_report_work (2) net 1 syz done 17 556d 1044d 0/29 auto-obsoleted due to no activity on 2025/09/25 13:43
upstream INFO: rcu detected stall in nsim_dev_trap_report_work net 1 syz 4 1099d 1142d 23/29 fixed on 2023/10/12 12:48
linux-6.1 INFO: rcu detected stall in nsim_dev_trap_report_work (3) 1 1 82d 82d 0/3 upstream: reported on 2026/06/20 12:13
upstream INFO: rcu detected stall in nsim_dev_trap_report_work (3) net 1 2 269d 269d 0/29 auto-obsoleted due to no activity on 2026/03/15 13:28
linux-6.1 INFO: rcu detected stall in nsim_dev_trap_report_work 1 2 849d 894d 0/3 auto-obsoleted due to no activity on 2024/08/22 01:13
linux-6.1 INFO: rcu detected stall in nsim_dev_trap_report_work (2) 1 1 503d 503d 0/3 auto-obsoleted due to no activity on 2025/08/03 09:20
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/05/25 04:11 26m retest repro linux-5.15.y report log
2026/02/28 20:22 14m retest repro linux-5.15.y report log
2025/12/06 16:49 54m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2026/09/02 09:26 0m fix candidate upstream error
2026/05/25 02:40 14m fix candidate upstream error job log
2026/04/13 14:52 9m fix candidate upstream error job log
2026/03/14 08:34 1m fix candidate upstream error job log
2026/02/12 04:36 1m fix candidate upstream error job log
2026/01/13 00:08 20m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=bd1/1/0x4000000000000002 softirq=7565/7566 fqs=5244 
	(detected by 1, t=10502 jiffies, g=9173, q=966)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:36 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:132 [inline]
RIP: 0010:rcu_read_unlock_special+0x3b2/0x4a0 kernel/rcu/tree_plugin.h:670
Code: 41 f7 c6 00 02 00 00 74 05 e8 9a d8 19 00 42 c6 44 2b 04 00 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 f7 44 24 40 00 02 00 00 <42> c6 44 2b 04 f8 75 24 f7 44 24 10 00 02 00 00 0f 84 b7 fc ff ff
RSP: 0018:ffffc900000073a0 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 1ffff92000000e78 RCX: ffffffff816561be
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88813fe28000
RBP: ffffc90000007480 R08: ffff88813fe28007 R09: 1ffff11027fc5000
R10: dffffc0000000000 R11: ffffed1027fc5001 R12: ffff8880b903b208
R13: dffffc0000000000 R14: ffff8880b903b1c0 R15: 1ffff11017207641
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000004 CR3: 000000000c08e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 __perf_event_output kernel/events/core.c:7823 [inline]
 perf_event_output_forward+0x255/0x2e0 kernel/events/core.c:7832
 __perf_event_overflow+0x35f/0x550 kernel/events/core.c:9525
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10057
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10031
 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 f2 0f 9d 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:ffffc90000007ae0 EFLAGS: 00000206
RAX: 6b80b2f6b4a1b100 RBX: 1ffff92000000f60 RCX: 6b80b2f6b4a1b100
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4540
RBP: ffffc90000007bc0 R08: ffffffff901ef1d7 R09: 1ffffffff203de3a
R10: dffffc0000000000 R11: fffffbfff203de3b R12: ffffffff8c323400
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]
 ieee80211_rx_napi+0x216/0x390 net/mac80211/rx.c:5021
 ieee80211_rx include/net/mac80211.h:4573 [inline]
 ieee80211_handle_queued_frames+0x104/0x1a0 net/mac80211/main.c:237
 tasklet_action_common+0x2ad/0x410 kernel/softirq.c:806
 handle_softirqs+0x336/0x830 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:crng_make_state+0x516/0x670 drivers/char/random.c:393
Code: 8e 72 05 e9 25 fd ff ff e8 97 b7 21 fd e8 22 1c 69 05 4d 85 f6 0f 84 ef fe ff ff e8 84 b7 21 fd fb 48 c7 44 24 20 0e 36 e0 45 <4b> c7 04 2c 00 00 00 00 4b c7 44 2c 08 00 00 00 00 4b c7 44 2c 10
RSP: 0018:ffffc90000d278e0 EFLAGS: 00000293
RAX: ffffffff8457581c RBX: 0000000000000000 RCX: ffff88813fe28000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000d27a10 R08: ffffffff901ef1d7 R09: 1ffffffff203de3a
R10: dffffc0000000000 R11: fffffbfff203de3b R12: 1ffff920001a4f20
R13: dffffc0000000000 R14: 0000000000000200 R15: ffffc90000d27a40
 _get_random_bytes+0xfc/0x250 drivers/char/random.c:405
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:691 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:721 [inline]
 nsim_dev_trap_report_work+0x646/0xab0 drivers/net/netdevsim/dev.c:762
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/06 11:06 linux-5.15.y 0996e0926f6b 4f7b22a0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/11/22 09:28 linux-5.15.y cc5ec8769306 4fb8ef37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/08/23 11:08 linux-5.15.y 0eb903b5b519 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/07/30 05:03 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/07/08 05:05 linux-5.15.y c86c4726e7f0 76cdc0c0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/05/10 15:23 linux-5.15.y de8dfb3f0278 29233ece .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/05/02 23:43 linux-5.15.y ef251c45f1cd a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/04/22 04:19 linux-5.15.y b9d57c40a767 0b6ab7ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2026/02/14 19:00 linux-5.15.y e45d5d41c134 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/12/31 04:22 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/12/28 21:00 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/12/25 10:50 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/12/25 08:54 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/12/08 00:30 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in nsim_dev_trap_report_work
2025/11/17 17:55 linux-5.15.y cc5ec8769306 ef766cd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in nsim_dev_trap_report_work
2025/10/21 01:13 linux-5.15.y ac56c046adf4 d422939c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in nsim_dev_trap_report_work
2025/08/20 06:56 linux-5.15.y c79648372d02 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in nsim_dev_trap_report_work
* Struck through repros no longer work on HEAD.