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: 5d11h, last: 5h30m
✨ 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=1 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=8 refcnt=9
    in-flight: 6264:reg_todo for 27s
    pending: 6*nsim_dev_hwstats_traffic_work, psi_avgs_work
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=11 refcnt=12
    pending: 4*nsim_dev_hwstats_traffic_work, 2*psi_avgs_work, 2*ovs_dp_masks_rebalance, free_obj_work, 2*psi_avgs_work
workqueue events_unbound: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=20 refcnt=21
    in-flight: 56:cfg80211_wiphy_work for 64s cfg80211_wiphy_work ,4950:cfg80211_wiphy_work for 68s cfg80211_wiphy_work ,7165:nsim_dev_trap_report_work for 9s ,12:cfg80211_wiphy_work for 69s cfg80211_wiphy_work ,1457:cfg80211_wiphy_work for 63s cfg80211_wiphy_work
    pending: nsim_dev_trap_report_work, toggle_allocation_gate, 5*nsim_dev_trap_report_work, flush_memcg_stats_dwork, 3*nsim_dev_trap_report_work
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=8 refcnt=9
    in-flight: 52:cfg80211_wiphy_work for 67s cfg80211_wiphy_work ,13:cfg80211_wiphy_work for 67s cfg80211_wiphy_work ,40:cfg80211_wiphy_work for 62s cfg80211_wiphy_work ,264:cfg80211_wiphy_work for 34s cfg80211_wiphy_work
workqueue events_power_efficient: flags=0x82
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=8 refcnt=9
    in-flight: 1188:neigh_periodic_work for 41s ,7164:gc_worker for 2s
    pending: crda_timeout_work, neigh_periodic_work, wg_ratelimiter_gc_entries, reg_check_chans_work, 2*neigh_managed_work
workqueue events_dfl_long: flags=0x2
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=6 refcnt=7
    pending: 6*defense_work_handler
workqueue mm_percpu_wq: flags=0x108
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=1 refcnt=2
    pending: vmstat_update
workqueue bat_events: flags=0x6000a
  pwq 8: cpus=0-1 flags=0x6 nice=0 active=1 refcnt=45 MAYDAY
    in-flight: 2852(RESCUER):batadv_tt_purge for 11s
    pending: mayday_cursor_func
    inactive: 2*batadv_tt_purge, batadv_dat_purge, 2*batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, batadv_bla_periodic_work, batadv_dat_purge, 4*batadv_mcast_mla_update, 2*batadv_iv_send_outstanding_bat_ogm_packet, 2*batadv_purge_orig, 6*batadv_iv_send_outstanding_bat_ogm_packet, 2*batadv_purge_orig, batadv_dat_purge, batadv_bla_periodic_work, 4*batadv_iv_send_outstanding_bat_ogm_packet, batadv_purge_orig, batadv_tt_purge, batadv_mcast_mla_update, 3*batadv_iv_send_outstanding_bat_ogm_packet, 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 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_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 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
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 6: cpus=1 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-crypt-wg0: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_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 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 6: cpus=1 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-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 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg1: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=3 refcnt=4
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker, wg_packet_decrypt_worker
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 6: cpus=1 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 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_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 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
workqueue wg-crypt-wg2: flags=0x128
  pwq 6: cpus=1 node=0 flags=0x0 nice=0 active=2 refcnt=3
    pending: wg_packet_encrypt_worker, wg_packet_tx_worker
pool 2: cpus=0 node=0 flags=0x0 nice=0 hung=0s workers=10 idle: 4833 9 4790 6306 5581 4834 6772 10 1009
pool 8: cpus=0-1 flags=0x6 nice=0 hung=2s workers=12 manager: 7166
Showing backtraces of busy workers in stalled worker pools:
pool 6: no worker in running state, cpu=1 is busy (nr_workers=11 nr_idle=11)
The pool might have trouble waking an idle worker.
Backtrace of last woken worker:
task:kworker/1:1     state:R  running task     stack:0     pid:26    tgid:26    ppid:2      task_flags:0x4208060 flags:0x00000010
Workqueue:  0x0 (wg-crypt-wg0)
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
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 2852 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
Workqueue: bat_events batadv_tt_purge
pstate: 03400005 (nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : in_softirq_really kernel/kcov.c:167 [inline]
pc : check_kcov_mode+0x18/0x54 kernel/kcov.c:179
lr : write_comp_data+0x38/0x84 kernel/kcov.c:242
sp : ffff80008ec46dd0
x29: ffff80008ec46dd0 x28: dfff800000000000 x27: 000000000000224e
x26: dfff800000000000 x25: ffff700011d88dc8 x24: 1ffff00011d88dfa
x23: ffff0000c8e9d880 x22: 0000000000000007 x21: 0000000000000002
x20: ffff000023a0f400 x19: ffff800085709eb4 x18: 0000000011264820
x17: 0000000001320140 x16: 0140000800000000 x15: 0000000000000000
x14: 00000000850ade10 x13: 0000000000000007 x12: 0000000000000000
x11: 0000000000000000 x10: 000000000000000f x9 : 0000000000000101
x8 : ffff0000c8e9d880 x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : 0000000000000000 x3 : ffff800085709eb4
x2 : ffff000023a0f400 x1 : ffff0000c8e9d880 x0 : 0000000000000003
Call trace:
 preempt_count arch/arm64/include/asm/preempt.h:12 [inline] (P)
 in_softirq_really kernel/kcov.c:167 [inline] (P)
 check_kcov_mode+0x18/0x54 kernel/kcov.c:179 (P)
 __sanitizer_cov_trace_const_cmp8+0x24/0x30 kernel/kcov.c:317
 __xfrm_decode_session+0x484/0x8a8 net/xfrm/xfrm_policy.c:3524
 xfrm_decode_session include/net/xfrm.h:1357 [inline]
 ip_route_me_harder+0x7c4/0xd80 net/ipv4/netfilter.c:67
 synproxy_send_tcp+0x2d4/0x5a4 net/netfilter/nf_synproxy_core.c:434
 synproxy_send_client_synack+0x3b0/0x640 net/netfilter/nf_synproxy_core.c:487
 nft_synproxy_eval_v4+0x16c/0x278 net/netfilter/nft_synproxy.c:59
 nft_synproxy_do_eval+0x2d8/0x4a4 net/netfilter/nft_synproxy.c:141
 nft_synproxy_eval+0x34/0x48 net/netfilter/nft_synproxy.c:247
 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
 nft_do_chain+0x418/0x13c8 net/netfilter/nf_tables_core.c:285
 nft_do_chain_inet+0x284/0x3d4 net/netfilter/nft_chain_filter.c:162
 nf_hook_entry_hookfn include/linux/netfilter.h:165 [inline]
 nf_hook_slow+0xc8/0x224 net/netfilter/core.c:619
 nf_hook include/linux/netfilter.h:280 [inline]
 NF_HOOK+0x1f0/0x398 include/linux/netfilter.h:323
 ip_local_deliver+0x128/0x188 net/ipv4/ip_input.c:262
 dst_input include/net/dst.h:480 [inline]
 ip_rcv_finish+0x20c/0x230 net/ipv4/ip_input.c:492
 NF_HOOK+0x308/0x398 include/linux/netfilter.h:325
 ip_rcv+0x7c/0x9c net/ipv4/ip_input.c:612
 __netif_receive_skb_one_core+0xc8/0x110 net/core/dev.c:6264
 __netif_receive_skb+0x34/0x128 net/core/dev.c:6377
 process_backlog+0x5f4/0x16f8 net/core/dev.c:6728
 __napi_poll+0xb4/0x328 net/core/dev.c:7787
 napi_poll net/core/dev.c:7850 [inline]
 net_rx_action+0x5b0/0xc14 net/core/dev.c:8007
 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 (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.