syzbot


INFO: rcu detected stall in batadv_dat_purge

Status: upstream: reported on 2025/11/22 07:27
Reported-by: syzbot+c06d79dd7c8f1ca76fe0@syzkaller.appspotmail.com
First crash: 1d09h, last: 1d09h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in batadv_dat_purge (3) batman 1 1 195d 195d 0/29 auto-obsoleted due to no activity on 2025/08/09 21:42
upstream INFO: rcu detected stall in batadv_dat_purge (2) kernel 1 1 1053d 1053d 0/29 auto-obsoleted due to no activity on 2023/04/12 18:40
upstream INFO: rcu detected stall in batadv_dat_purge batman 1 1 1503d 1503d 0/29 auto-closed as invalid on 2022/01/10 03:55
linux-5.15 BUG: soft lockup in batadv_dat_purge 1 1 909d 909d 0/3 auto-obsoleted due to no activity on 2023/09/06 15:35

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 ticks this GP) idle=4fd/1/0x4000000000000000 softirq=34534/34534 fqs=2100 
	(detected by 1, t=10504 jiffies, g=44837, q=2208)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6894 Comm: kworker/u4:8 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: bat_events batadv_dat_purge
RIP: 0010:check_preemption_disabled+0x6/0x110 lib/smp_processor_id.c:13
Code: dd 12 8a e8 2c 01 00 00 65 ff 0d 91 d6 59 76 5b c3 00 00 cc 48 c7 c7 20 e5 59 8a 48 c7 c6 60 e5 59 8a eb 00 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 49
RSP: 0018:ffffc90000006f58 EFLAGS: 00000003
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff815bfaab
RDX: 0000000000000000 RSI: ffffffff8a59e560 RDI: ffffffff8a59e520
RBP: ffffc900000070b8 R08: dffffc0000000000 R09: fffffbfff1ad33a6
R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffffffff8c11c760
R13: 1ffff92000000e00 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2b613b CR3: 000000000be8e000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:331 [inline]
 rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:1123
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0xcd/0x3f0 kernel/locking/lockdep.c:5594
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 __perf_event_output kernel/events/core.c:7800 [inline]
 perf_event_output_forward+0x9e/0x280 kernel/events/core.c:7822
 __perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
 perf_swevent_overflow kernel/events/core.c:9591 [inline]
 perf_swevent_event+0x4ad/0x530 kernel/events/core.c:9629
 perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2be/0x380 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+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ed 11 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc900000077a0 EFLAGS: 00000206
RAX: f0bc86f57cb15200 RBX: 1ffff92000000ef8 RCX: f0bc86f57cb15200
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: ffffffff8a59e580
RBP: ffffc90000007880 R08: dffffc0000000000 R09: fffffbfff1ff7c39
R10: fffffbfff1ff7c39 R11: 1ffffffff1ff7c38 R12: ffffffff8c120c00
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]
 ndisc_send_skb+0xdc4/0x14a0 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x2b8/0x600 net/ipv6/addrconf.c:3956
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 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:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x132/0x1b0 kernel/softirq.c:408
Code: 8a e8 92 0b 61 08 65 66 8b 05 8a 25 bb 7e 66 85 c0 75 54 bf 01 00 00 00 e8 ab fe 08 00 e8 66 76 35 00 fb 65 8b 05 36 fc b9 7e <85> c0 75 05 e8 e5 06 b8 ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc9000325fb40 EFLAGS: 00000286
RAX: 0000000080000000 RBX: 0000000000000201 RCX: f0bc86f57cb15200
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: ffffffff8a59e580
RBP: ffffc9000325fbc8 R08: dffffc0000000000 R09: fffffbfff1ff7c3e
R10: fffffbfff1ff7c3e R11: 1ffffffff1ff7c3d R12: ffffffff897c084b
R13: ffff88805ba39c58 R14: dffffc0000000000 R15: 1ffff9200064bf68
 spin_unlock_bh include/linux/spinlock.h:409 [inline]
 __batadv_dat_purge net/batman-adv/distributed-arp-table.c:186 [inline]
 batadv_dat_purge+0x2db/0x3c0 net/batman-adv/distributed-arp-table.c:205
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/22 07:27 linux-5.15.y cc5ec8769306 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in batadv_dat_purge
* Struck through repros no longer work on HEAD.