syzbot


INFO: rcu detected stall in gc_worker

Status: upstream: reported C repro on 2023/07/03 02:12
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+458308355e7401f2f4c5@syzkaller.appspotmail.com
First crash: 839d, last: 7d19h
Bug presence (2)
Date Name Commit Repro Result
2025/10/11 linux-6.1.y (ToT) 882efbdd9d34 C [report] INFO: rcu detected stall in corrupted
2025/10/11 upstream (ToT) 0739473694c4 C Didn't crash
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in gc_worker (2) netfilter 1 C unreliable 4 1372d 1409d 0/29 closed as invalid on 2022/02/08 10:33
upstream INFO: rcu detected stall in gc_worker (3) netfilter 1 C done done 228 1d09h 1308d 0/29 upstream: reported C repro on 2022/03/20 12:02
upstream INFO: rcu detected stall in gc_worker netfilter 1 8 2376d 2461d 0/29 auto-closed as invalid on 2019/10/14 16:34
linux-5.15 INFO: rcu detected stall in gc_worker origin:upstream 1 C error 98 2d07h 804d 0/3 upstream: reported C repro on 2023/08/06 21:00
linux-4.19 INFO: rcu detected stall in gc_worker 1 syz error 1 1275d 1275d 0/1 upstream: reported syz repro on 2022/04/22 15:43
Fix bisection attempts (9)
Created Duration User Patch Repo Result
2025/06/04 07:50 2h06m bisect fix linux-6.1.y OK (0) job log log
2025/02/13 23:57 1h28m bisect fix linux-6.1.y OK (0) job log log
2025/01/11 18:43 2h07m bisect fix linux-6.1.y OK (0) job log log
2024/04/24 07:31 2h33m bisect fix linux-6.1.y OK (0) job log log
2024/02/16 22:50 2h26m bisect fix linux-6.1.y OK (0) job log log
2024/01/07 17:15 2h06m bisect fix linux-6.1.y OK (0) job log log
2023/11/26 07:58 2h12m bisect fix linux-6.1.y OK (0) job log log
2023/10/24 21:30 2h00m bisect fix linux-6.1.y OK (0) job log log
2023/09/18 17:35 2h25m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7/1:b..l
	(detected by 1, t=10502 jiffies, g=8797, q=128 ncpus=2)
task:kworker/0:0     state:R  running task     stack:25096 pid:7     ppid:2      flags:0x00004000
Workqueue: events_power_efficient gc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:seqcount_lockdep_reader_access+0x17b/0x1c0 include/linux/seqlock.h:105
Code: f9 4d 85 e4 75 16 e8 84 39 1f f9 eb 15 e8 7d 39 1f f9 e8 08 bc b5 01 4d 85 e4 74 ea e8 6e 39 1f f9 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 66 43 c7 44 3e 09 00 00 43 c6 44 3e 0b 00
RSP: 0018:ffffc900000c7a20 EFLAGS: 00000293
RAX: ffffffff886196b2 RBX: 0000000000000000 RCX: ffff88813fe4bb80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000c7ad0 R08: dffffc0000000000 R09: fffffbfff215c45a
R10: fffffbfff215c45a R11: 1ffffffff215c459 R12: 0000000000000200
R13: ffffffff9700de60 R14: 1ffff92000018f44 R15: dffffc0000000000
 nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:354 [inline]
 gc_worker+0x30c/0x13d0 net/netfilter/nf_conntrack_core.c:1517
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 10523 jiffies! g8797 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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4299 Comm: syz-executor291 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:101 [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+0x58/0x290 mm/kasan/generic.c:189
Code: 00 00 49 bf 01 00 00 00 00 fc ff df 49 89 fb 49 c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 <4e> 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 4d 85 f6 0f 84 39
RSP: 0018:ffffc90003c77a20 EFLAGS: 00000807
RAX: 0000000000000001 RBX: 1ffffffff1c3ee4d RCX: ffffffff8162f209
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e1f7268
RBP: ffffc90003c77b48 R08: dffffc0000000000 R09: fffffbfff1c3ee4d
R10: ffffed100f8cd863 R11: 1ffffffff1c3ee4d R12: 0000000000000000
R13: 1ffff9200078ef54 R14: 0000000000000000 R15: dffffc0000000001
FS:  0000555565d0c3c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff6bc8c9ba0 CR3: 00000000765d3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:444 [inline]
 cpu_online include/linux/cpumask.h:1030 [inline]
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0xd9/0x490 kernel/locking/lockdep.c:5633
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 dequeue_signal+0x1cd/0x4b0 kernel/signal.c:705
 get_signal+0x547/0x1350 kernel/signal.c:2751
 arch_do_signal_or_restart+0xb0/0x1230 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff6bc8b2249
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 1b 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdde2d28f8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007ff6bc8b2249
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007ff6bc86a990 R09: 00007ff6bc86a990
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdde2d291c
R13: 00007ffdde2d2950 R14: 00007ffdde2d2930 R15: 0000000000000002
 </TASK>

Crashes (91):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/08 21:04 linux-6.1.y 28c695c365e1 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/05/04 11:17 linux-6.1.y b6736e03756f b0714e37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/05/03 21:02 linux-6.1.y b6736e03756f b0714e37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/04/13 09:26 linux-6.1.y 420102835862 0bd6db41 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/27 12:08 linux-6.1.y 344a09659766 20510e88 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/22 12:58 linux-6.1.y 344a09659766 c6512ef7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/21 13:54 linux-6.1.y 344a09659766 62330552 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/10/27 12:04 linux-6.1.y 7ec6f9fa3d97 65e8686b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/03/24 18:18 linux-6.1.y d7543167affd 0ea90952 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/02/24 05:36 linux-6.1.y 81e1dc2f7001 8d446f15 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2023/07/03 02:12 linux-6.1.y 0f4ac6b4c5f0 bfc47836 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/04/12 13:29 linux-6.1.y 420102835862 0bd6db41 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: rcu detected stall in gc_worker
2025/10/11 07:58 linux-6.1.y 882efbdd9d34 ff1712fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/10/08 15:14 linux-6.1.y 882efbdd9d34 7e2882b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/10/02 18:44 linux-6.1.y 882efbdd9d34 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/09/25 17:21 linux-6.1.y 7b34dc04e4ff 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/08/12 02:52 linux-6.1.y 3594f306da12 c06e8995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/08/09 11:04 linux-6.1.y 3594f306da12 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/07/18 07:48 linux-6.1.y 3369c6df2fae 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/07/07 02:47 linux-6.1.y 04d1ccaa9c28 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/07/02 11:21 linux-6.1.y 7e69c33e4858 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/06/24 10:30 linux-6.1.y 58485ff1a74f e2f27c35 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/06/16 00:16 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/06/05 07:03 linux-6.1.y 58485ff1a74f 6b6b5f21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/04/11 13:59 linux-6.1.y 420102835862 94486846 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/04/06 11:36 linux-6.1.y 8e60a714ba3b 1c65791e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/21 07:33 linux-6.1.y 344a09659766 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/20 01:40 linux-6.1.y 344a09659766 e20d7b13 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/03/07 08:03 linux-6.1.y 3a8358583626 831e3629 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/02/28 09:49 linux-6.1.y 3a8358583626 6a8fcbc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2025/02/25 12:17 linux-6.1.y 3a8358583626 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/11/22 13:59 linux-6.1.y b67dc5c9ade9 4b25d554 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/11/15 20:55 linux-6.1.y 59d7b1a7104a cfe3a04a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/10/06 14:50 linux-6.1.y aa4cd140bba5 d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/09/21 03:40 linux-6.1.y e526b12bf916 6f888b75 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in gc_worker
2024/09/19 09:21 linux-6.1.y e526b12bf916 c673ca06 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/09/07 06:48 linux-6.1.y 699506173494 9750182a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/08/21 21:11 linux-6.1.y ee5e09825b81 db5852f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/08/15 20:37 linux-6.1.y 117ac406ba90 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/08/13 23:10 linux-6.1.y 36790ef5e00b f21a18ca .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/08/12 18:26 linux-6.1.y 36790ef5e00b 842184b3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/08/10 01:19 linux-6.1.y 48d525b0e463 a83d9288 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/27 15:10 linux-6.1.y c1cec4dad96b 46eb10b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/26 23:52 linux-6.1.y c18e82d3ee44 46eb10b7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/19 11:57 linux-6.1.y 9b3f9a5b12dc ee4e11c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/18 09:31 linux-6.1.y cac15753b8ce 0f902625 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/15 07:49 linux-6.1.y 266ee8e06d5b c605e6a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/11 01:48 linux-6.1.y 7753af06eebf 6f7fa383 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/10 01:13 linux-6.1.y 7753af06eebf 79d68ada .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/06 09:42 linux-6.1.y 7753af06eebf 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/07/06 05:37 linux-6.1.y 7753af06eebf 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/06/28 11:29 linux-6.1.y 99e6a620de00 6ef39602 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/06/26 13:09 linux-6.1.y eb44d83053d6 c6d33a01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/06/26 07:03 linux-6.1.y eb44d83053d6 dec8bc94 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2024/06/08 04:33 linux-6.1.y 88690811da69 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
2023/07/03 08:44 linux-6.1.y 0f4ac6b4c5f0 bfc47836 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in gc_worker
* Struck through repros no longer work on HEAD.