============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- kworker/u4:12/2976 is trying to acquire lock: ffff888030f04d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff888030f04d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: hsr_dev_xmit+0x1dc/0x350 net/hsr/hsr_device.c:237 but task is already holding lock: ffff88807e458d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff88807e458d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: send_hsr_supervision_frame+0x311/0xb90 net/hsr/hsr_device.c:323 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&hsr->seqnr_lock); lock(&hsr->seqnr_lock); *** DEADLOCK *** May be due to missing lock nesting notation 11 locks held by kworker/u4:12/2976: #0: ffff88814ca4a538 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #0: ffff88814ca4a538 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #1: ffffc9000bc57d00 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline] #1: ffffc9000bc57d00 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730 #2: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #2: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #2: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] #2: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: batadv_nc_worker+0xd2/0x610 net/batman-adv/network-coding.c:719 #3: ffffc900001f0c00 ((&hsr->announce_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd2/0x540 kernel/time/timer.c:1698 #4: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #4: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #4: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: hsr_announce+0x84/0x350 net/hsr/hsr_device.c:400 #5: ffff88807e458d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #5: ffff88807e458d80 (&hsr->seqnr_lock){+.-.}-{2:2}, at: send_hsr_supervision_frame+0x311/0xb90 net/hsr/hsr_device.c:323 #6: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #6: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #6: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: hsr_forward_skb+0xa5/0x2140 net/hsr/hsr_forward.c:621 #7: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #7: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:838 [inline] #7: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x265/0x3660 net/core/dev.c:4363 #8: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #8: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #8: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x196/0x1900 net/bridge/br_device.c:50 #9: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #9: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:838 [inline] #9: ffffffff8d1320c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x265/0x3660 net/core/dev.c:4363 #10: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #10: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #10: ffffffff8d132060 (rcu_read_lock){....}-{1:2}, at: hsr_dev_xmit+0x2d/0x350 net/hsr/hsr_device.c:231 stack backtrace: CPU: 1 PID: 2976 Comm: kworker/u4:12 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: bat_events batadv_nc_worker Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3856 [inline] __lock_acquire+0x5dbc/0x7d40 kernel/locking/lockdep.c:5137 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] hsr_dev_xmit+0x1dc/0x350 net/hsr/hsr_device.c:237 __netdev_start_xmit include/linux/netdevice.h:4943 [inline] netdev_start_xmit include/linux/netdevice.h:4957 [inline] xmit_one net/core/dev.c:3632 [inline] dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3648 __dev_queue_xmit+0x19a3/0x3660 net/core/dev.c:4442 dev_queue_xmit include/linux/netdevice.h:3113 [inline] br_dev_queue_push_xmit+0x6b3/0x870 net/bridge/br_forward.c:53 NF_HOOK+0x351/0x3e0 include/linux/netfilter.h:304 br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66 NF_HOOK+0x351/0x3e0 include/linux/netfilter.h:304 __br_forward+0x433/0x610 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb5/0x150 net/bridge/br_forward.c:191 br_flood+0x31b/0x670 net/bridge/br_forward.c:237 br_dev_xmit+0x127c/0x1900 net/bridge/br_device.c:106 __netdev_start_xmit include/linux/netdevice.h:4943 [inline] netdev_start_xmit include/linux/netdevice.h:4957 [inline] xmit_one net/core/dev.c:3632 [inline] dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3648 __dev_queue_xmit+0x19a3/0x3660 net/core/dev.c:4442 dev_queue_xmit include/linux/netdevice.h:3113 [inline] hsr_xmit net/hsr/hsr_forward.c:382 [inline] hsr_forward_do net/hsr/hsr_forward.c:473 [inline] hsr_forward_skb+0x1335/0x2140 net/hsr/hsr_forward.c:626 send_hsr_supervision_frame+0x5fb/0xb90 net/hsr/hsr_device.c:346 hsr_announce+0x198/0x350 net/hsr/hsr_device.c:402 call_timer_fn+0x189/0x540 kernel/time/timer.c:1701 expire_timers kernel/time/timer.c:1752 [inline] __run_timers+0x542/0x800 kernel/time/timer.c:2023 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036 handle_softirqs+0x280/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758 Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25 RSP: 0018:ffffc9000bc57a40 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: f4192f96c5f0a400 RDX: 0000000000000000 RSI: ffffffff8acadae0 RDI: ffffffff8b1c85a0 RBP: ffffc9000bc57b48 R08: dffffc0000000000 R09: 1ffffffff22382a0 R10: dffffc0000000000 R11: fffffbfff22382a1 R12: 1ffff9200178af54 R13: ffffffff8d132060 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:408 [inline] batadv_nc_worker+0xef/0x610 net/batman-adv/network-coding.c:719 process_one_work kernel/workqueue.c:2653 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 ---------------- Code disassembly (best guess): 0: f7 84 24 80 00 00 00 testl $0x200,0x80(%rsp) 7: 00 02 00 00 b: 43 c6 44 3c 04 f8 movb $0xf8,0x4(%r12,%r15,1) 11: 0f 85 f0 00 00 00 jne 0x107 17: 41 f7 c6 00 02 00 00 test $0x200,%r14d 1e: 74 01 je 0x21 20: fb sti 21: 48 c7 44 24 60 0e 36 movq $0x45e0360e,0x60(%rsp) 28: e0 45 * 2a: 4b c7 04 3c 00 00 00 movq $0x0,(%r12,%r15,1) <-- trapping instruction 31: 00 32: 43 c7 44 3c 08 00 00 movl $0x0,0x8(%r12,%r15,1) 39: 00 00 3b: 65 gs 3c: 48 rex.W 3d: 8b .byte 0x8b 3e: 04 25 add $0x25,%al