syzbot


INFO: rcu detected stall in batadv_mcast_mla_update (2)

Status: upstream: reported on 2025/08/30 12:06
Reported-by: syzbot+551695bf01bd0a4a6385@syzkaller.appspotmail.com
First crash: 204d, last: 11d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in batadv_mcast_mla_update 1 1 391d 391d 0/3 auto-obsoleted due to no activity on 2025/06/04 18:56
upstream INFO: rcu detected stall in batadv_mcast_mla_update batman 1 6 543d 638d 0/29 auto-obsoleted due to no activity on 2024/12/24 16:54
upstream INFO: rcu detected stall in batadv_mcast_mla_update (2) batman 1 C error error 7 39d 90d 0/29 upstream: reported C repro on 2025/12/22 05:27

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=723/1/0x4000000000000000 softirq=25068/25070 fqs=5247 
	(detected by 1, t=10502 jiffies, g=30433, q=1060)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 144 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: bat_events batadv_mcast_mla_update
RIP: 0010:perf_tp_event_match kernel/events/core.c:9995 [inline]
RIP: 0010:perf_tp_event+0x244/0xbf0 kernel/events/core.c:10046
Code: e8 a1 4d cc ff 84 c0 0f 84 c5 02 00 00 e8 64 9f e0 ff e9 0c 03 00 00 48 8b 44 24 20 4c 8d a0 88 00 00 00 4c 89 e3 48 c1 eb 03 <4d> 8d bd d8 01 00 00 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc
RSP: 0018:ffffc90000007640 EFLAGS: 00000046
RAX: ffffffff81988342 RBX: 1ffff11017206a4a RCX: ffff888017a83b80
RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc900000078c8 R08: ffff888017a83b87 R09: 1ffff11002f50770
R10: dffffc0000000000 R11: ffffed1002f50771 R12: ffff8880b9035250
R13: ffff8880721723d0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f110eeb7dac CR3: 000000007a8cb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 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 12 f2 9c 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:ffffc90000007b00 EFLAGS: 00000206
RAX: 5359c00e008b5700 RBX: 1ffff92000000f64 RCX: 5359c00e008b5700
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: ffffffff8a79f980
RBP: ffffc90000007bd8 R08: ffffffff901d41b7 R09: 1ffffffff203a836
R10: dffffc0000000000 R11: fffffbfff203a837 R12: ffffffff8c322f00
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_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4f2/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 handle_softirqs+0x339/0x830 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:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:206
Code: a4 4e 89 7e 65 8b 15 a5 4e 89 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 10 16 00 00 <83> fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 48 8d 7e 01 8b 89 14
RSP: 0018:ffffc9000155f9b8 EFLAGS: 00000246
RAX: ffffffff8135fbad RBX: ffff888056df3780 RCX: ffff888017a83b80
RDX: 0000000000000000 RSI: ffff888056df3780 RDI: ffff888056df3780
RBP: 0000000000000001 R08: 0000000000000000 R09: 1ffffffff203a836
R10: dffffc0000000000 R11: fffffbfff203a837 R12: ffffffff81bd979f
R13: ffff888056df3780 R14: ffff888016c41500 R15: 0000000000000000
 __phys_addr+0xd/0x170 arch/x86/mm/physaddr.c:16
 virt_to_head_page include/linux/mm.h:911 [inline]
 ____kasan_slab_free+0x1e/0x110 mm/kasan/common.c:344
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 batadv_mcast_mla_list_free net/batman-adv/multicast.c:638 [inline]
 __batadv_mcast_mla_update net/batman-adv/multicast.c:893 [inline]
 batadv_mcast_mla_update+0x2da9/0x3150 net/batman-adv/multicast.c:915
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 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 (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/11 20:09 linux-5.15.y 91d48252ad4b 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in batadv_mcast_mla_update
2025/12/04 00:09 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in batadv_mcast_mla_update
2025/11/24 19:57 linux-5.15.y cc5ec8769306 bf6fe8fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in batadv_mcast_mla_update
2025/08/30 12:05 linux-5.15.y 01879f56bdde 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in batadv_mcast_mla_update
* Struck through repros no longer work on HEAD.