BUG: workqueue lockup in batadv_tt_purge

Status: upstream: reported on 2026/09/15 15:10
Subsystems: netfilter
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+61b202fdc410840f0198@syzkaller.appspotmail.com
First crash: 6d13h, last: 17h25m
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
8ee1d451 repro-c 💥 BUG: workqueue lockup in batadv_tt_purge 2026/09/14 21:13 2026/09/15 00:49 2026/09/15 04:05 81a27d1a
85bbb2e5 repro-c Reproduced: ✅ BUG: workqueue lockup in batadv_tt_purge 2026/09/14 14:12 2026/09/14 14:12 2026/09/14 17:03 81a27d1a
d15d28ef assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ BUG: workqueue lockup in batadv_tt_purge 2026/09/12 00:51 2026/09/12 00:51 2026/09/12 00:57 6816f32e
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [netfilter?] BUG: workqueue lockup in batadv_tt_purge 0 (1) 2026/09/15 15:10
Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/09/14 18:11 14m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 704340f1cd0dcef829eb62f5b48ae95a2ce17bdf report job log log

Sample crash report:
BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 37s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x100
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=18 refcnt=19
    pending: 5*nsim_dev_hwstats_traffic_work, free_obj_work, 4*psi_avgs_work, vmstat_shepherd, psi_avgs_work, 5*ovs_dp_masks_rebalance, drm_fb_helper_damage_work
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=7 refcnt=8
    pending: 5*nsim_dev_hwstats_traffic_work, psi_avgs_work, ovs_dp_masks_rebalance
workqueue events_unbound: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=15 refcnt=16
    in-flight: 1180:nsim_dev_trap_report_work for 3s ,7572:cfg80211_wiphy_work for 82s cfg80211_wiphy_work ,12:cfg80211_wiphy_work for 83s cfg80211_wiphy_work ,7577:cfg80211_wiphy_work for 84s cfg80211_wiphy_work ,189:cfg80211_wiphy_work for 59s cfg80211_wiphy_work
    pending: 6*macvlan_process_broadcast
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=20 refcnt=21
    in-flight: 40:linkwatch_event for 92s ,3331:cfg80211_wiphy_work for 79s cfg80211_wiphy_work ,7574:cfg80211_wiphy_work for 73s cfg80211_wiphy_work ,93:nsim_dev_trap_report_work for 21s ,42:cfg80211_wiphy_work for 82s cfg80211_wiphy_work ,7576:nsim_dev_trap_report_work for 11s ,13:cfg80211_wiphy_work for 89s cfg80211_wiphy_work
    pending: 2*nsim_dev_trap_report_work, toggle_allocation_gate, 5*nsim_dev_trap_report_work, flush_memcg_stats_dwork
workqueue events_power_efficient: flags=0x82
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=6 refcnt=7
    in-flight: 3484:neigh_periodic_work for 81s ,7573:reg_check_chans_work for 39s
    pending: fb_flashcursor, neigh_managed_work, gc_worker, wg_ratelimiter_gc_entries
workqueue events_dfl_long: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    pending: 2*defense_work_handler
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=4 refcnt=5
    pending: 4*defense_work_handler
workqueue mm_percpu_wq: flags=0x108
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
workqueue iou_exit: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    in-flight: 3240:io_ring_exit_work for 12s
workqueue ipv6_addrconf: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=9 MAYDAY
    in-flight: 2819(RESCUER):addrconf_verify_work for 38s
    inactive: 3*addrconf_verify_work
workqueue bat_events: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=47 MAYDAY
    in-flight: 2851(RESCUER):batadv_tt_purge for 16s
    inactive: 2*batadv_tt_purge, batadv_dat_purge, 2*batadv_bla_periodic_work, batadv_dat_purge, batadv_mcast_mla_update, batadv_bla_periodic_work, 2*batadv_dat_purge, 2*batadv_bla_periodic_work, batadv_dat_purge, 4*batadv_mcast_mla_update, batadv_purge_orig, 7*batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, 5*batadv_iv_send_outstanding_bat_ogm_packet, 2*batadv_purge_orig, 5*batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, 2*batadv_tt_purge
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    in-flight: 4804:wg_packet_tx_worker for 43s wg_packet_tx_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_encrypt_worker
workqueue wg-kex-wg1: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4811:wg_packet_handshake_receive_worker for 10s
workqueue wg-kex-wg1: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    in-flight: 7571:wg_packet_handshake_send_worker for 7s
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_decrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_encrypt_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_receive_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 24:wg_packet_handshake_receive_worker for 34s
workqueue wg-kex-wg2: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_encrypt_worker
workqueue wg-kex-wg1: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    pending: wg_packet_handshake_send_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg2: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=2 refcnt=3
    pending: 2*wg_packet_handshake_send_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: wg_packet_encrypt_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg0: flags=0x124
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4814:wg_packet_handshake_receive_worker for 45s
workqueue wg-kex-wg0: flags=0x6
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=2
    in-flight: 7570:wg_packet_handshake_send_worker for 4s
workqueue wg-crypt-wg0: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4837:wg_packet_encrypt_worker for 4s
workqueue wg-crypt-wg1: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_decrypt_worker, wg_packet_tx_worker
workqueue wg-kex-wg2: flags=0x124
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4716:wg_packet_handshake_receive_worker for 10s
workqueue wg-crypt-wg2: flags=0x128
  pwq 2: cpus=0 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    in-flight: 4466:wg_packet_encrypt_worker for 11s
pool 6: cpus=1 node=0 flags=0x0 nice=0 hung=4s workers=10 idle: 26 4797 1870
pool 8: cpus=0-1 flags=0x6 nice=0 hung=3s workers=18 manager: 10563
Showing backtraces of busy workers in stalled worker pools:
pool 2: no worker in running state, cpu=0 is busy (nr_workers=10 nr_idle=10)
The pool might have trouble waking an idle worker.
Backtrace of last woken worker:
task:kworker/0:2     state:R  running task     stack:0     pid:866   tgid:866   ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue:  0x0 (events)
Call trace:
 __switch_to+0x2b4/0x6e4 arch/arm64/kernel/process.c:775 (T)
 context_switch kernel/sched/core.c:5520 [inline]
 __schedule+0x1370/0x2d80 kernel/sched/core.c:7270
 __schedule_loop kernel/sched/core.c:7347 [inline]
 schedule+0x13c/0x20c kernel/sched/core.c:7362
 worker_thread+0x924/0xbd0 kernel/workqueue.c:3566
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 2851 Comm: kworker/R-bat_e Tainted: G             L      syzkaller #0 PREEMPT 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
Workqueue: bat_events batadv_tt_purge
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x270/0x2b8 lib/nmi_backtrace.c:123
 nmi_trigger_cpumask_backtrace+0x1c0/0x430 lib/nmi_backtrace.c:66
 arch_trigger_cpumask_backtrace+0x30/0x40 arch/arm64/kernel/smp.c:972
 cpumask_backtrace+0x28/0x38 lib/nmi_backtrace.c:136
 trigger_single_cpu_backtrace include/linux/nmi.h:182 [inline]
 show_cpu_pool_busy_workers kernel/workqueue.c:7876 [inline]
 show_cpu_pools_busy_workers+0x640/0x830 kernel/workqueue.c:7890
 wq_watchdog_timer_fn+0x648/0x740 kernel/workqueue.c:8006
 call_timer_fn+0x194/0xa4c kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x530/0x744 kernel/time/timer.c:2386
 run_timer_base+0x84/0x1b8 kernel/time/timer.c:2395
 run_timer_softirq+0x28/0x48 kernel/time/timer.c:2406
 handle_softirqs+0x2ec/0xd98 kernel/softirq.c:645
 __do_softirq+0x14/0x20 kernel/softirq.c:679
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:78
 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:885
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:83
 do_softirq+0x90/0xf8 kernel/softirq.c:546
 __local_bh_enable_ip+0x240/0x35c kernel/softirq.c:473
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x3c/0x4c kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 batadv_tt_global_purge net/batman-adv/translation-table.c:2390 [inline]
 batadv_tt_purge+0x3e4/0x7b4 net/batman-adv/translation-table.c:3754
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0x91c/0x1250 kernel/workqueue.c:3470
 rescuer_thread+0x68c/0xd90 kernel/workqueue.c:3694
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/16 05:21 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/16 02:26 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/15 15:09 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/15 11:25 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/15 03:32 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 924033e8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/13 04:33 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
2026/09/10 09:39 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 5445d6419962 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 BUG: workqueue lockup in batadv_tt_purge
* Struck through repros no longer work on HEAD.