============================================ WARNING: possible recursive locking detected 6.16.0-rc4-syzkaller-00991-g6b9fd8857b9f #0 Not tainted -------------------------------------------- kworker/0:23/9176 is trying to acquire lock: ffff888046ed2f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff888046ed2f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220 net/hsr/hsr_device.c:234 but task is already holding lock: ffff88807b3c0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff88807b3c0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220 net/hsr/hsr_device.c:234 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/0:23/9176: #0: ffff88814c08a148 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline] #0: ffff88814c08a148 ((wq_completion)mld){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321 #1: ffffc90003c3fbc0 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #1: ffffc90003c3fbc0 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321 #2: ffff888045c53538 (&idev->mc_lock){+.+.}-{4:4}, at: mld_ifc_work+0x2d/0xde0 net/ipv6/mcast.c:2701 #3: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #3: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #3: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: mld_sendpack+0x1de/0xd80 net/ipv6/mcast.c:1840 #4: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #4: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x701/0x16a0 net/ipv6/ip6_output.c:126 #5: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #5: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27e/0x3a70 net/core/dev.c:4636 #6: ffff88807b3c0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #6: ffff88807b3c0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x19a/0x220 net/hsr/hsr_device.c:234 #7: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #7: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0x9e/0x2860 net/hsr/hsr_forward.c:728 #8: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #8: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27e/0x3a70 net/core/dev.c:4636 #9: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #9: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x185/0x1840 net/bridge/br_device.c:52 #10: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #10: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #10: ffffffff8e13ee80 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27e/0x3a70 net/core/dev.c:4636 stack backtrace: CPU: 0 UID: 0 PID: 9176 Comm: kworker/0:23 Not tainted 6.16.0-rc4-syzkaller-00991-g6b9fd8857b9f #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: mld mld_ifc_work Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3044 check_deadlock kernel/locking/lockdep.c:3096 [inline] validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3898 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __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+0x19a/0x220 net/hsr/hsr_device.c:234 __netdev_start_xmit include/linux/netdevice.h:5217 [inline] netdev_start_xmit include/linux/netdevice.h:5226 [inline] xmit_one net/core/dev.c:3828 [inline] dev_hard_start_xmit+0x2d4/0x830 net/core/dev.c:3844 __dev_queue_xmit+0x1adf/0x3a70 net/core/dev.c:4711 dev_queue_xmit include/linux/netdevice.h:3358 [inline] br_dev_queue_push_xmit+0x6c5/0x890 net/bridge/br_forward.c:53 NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:317 br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66 NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:317 __br_forward+0x41e/0x600 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb5/0x160 net/bridge/br_forward.c:190 br_flood+0x31a/0x6a0 net/bridge/br_forward.c:237 br_dev_xmit+0x11b3/0x1840 net/bridge/br_device.c:108 __netdev_start_xmit include/linux/netdevice.h:5217 [inline] netdev_start_xmit include/linux/netdevice.h:5226 [inline] xmit_one net/core/dev.c:3828 [inline] dev_hard_start_xmit+0x2d4/0x830 net/core/dev.c:3844 __dev_queue_xmit+0x1adf/0x3a70 net/core/dev.c:4711 dev_queue_xmit include/linux/netdevice.h:3358 [inline] hsr_xmit net/hsr/hsr_forward.c:430 [inline] hsr_forward_do net/hsr/hsr_forward.c:571 [inline] hsr_forward_skb+0x158b/0x2860 net/hsr/hsr_forward.c:733 hsr_dev_xmit+0x1a5/0x220 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5217 [inline] netdev_start_xmit include/linux/netdevice.h:5226 [inline] xmit_one net/core/dev.c:3828 [inline] dev_hard_start_xmit+0x2d4/0x830 net/core/dev.c:3844 __dev_queue_xmit+0x1adf/0x3a70 net/core/dev.c:4711 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x11fe/0x16a0 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:317 mld_sendpack+0x800/0xd80 net/ipv6/mcast.c:1868 mld_send_cr net/ipv6/mcast.c:2169 [inline] mld_ifc_work+0x835/0xde0 net/ipv6/mcast.c:2702 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245