============================================ WARNING: possible recursive locking detected 6.4.0-rc1-next-20230512-syzkaller #0 Not tainted -------------------------------------------- dhcpcd-run-hook/5080 is trying to acquire lock: ffff88807d721330 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff88807d721330 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_query net/bridge/br_multicast.c:3518 [inline] ffff88807d721330 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] ffff88807d721330 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x202d/0x6850 net/bridge/br_multicast.c:3969 but task is already holding lock: ffff888142b25330 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff888142b25330 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x61/0x360 net/bridge/br_multicast.c:1900 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&br->multicast_lock); lock(&br->multicast_lock); *** DEADLOCK *** May be due to missing lock nesting notation 5 locks held by dhcpcd-run-hook/5080: #0: ffffc90003b9fcb8 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:31 [inline] #0: ffffc90003b9fcb8 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd5/0x580 kernel/time/timer.c:1690 #1: ffff888142b25330 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #1: ffff888142b25330 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired+0x61/0x360 net/bridge/br_multicast.c:1900 #2: ffffffff8c799160 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22c/0x3c10 net/core/dev.c:4161 #3: ffffffff8c799160 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22c/0x3c10 net/core/dev.c:4161 #4: ffffffff8c7991c0 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x4/0x16d0 net/bridge/br_device.c:29 stack backtrace: CPU: 0 PID: 5080 Comm: dhcpcd-run-hook Not tainted 6.4.0-rc1-next-20230512-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:3006 [inline] check_deadlock kernel/locking/lockdep.c:3049 [inline] validate_chain kernel/locking/lockdep.c:3834 [inline] __lock_acquire+0x13eb/0x5f30 kernel/locking/lockdep.c:5088 lock_acquire.part.0+0x11c/0x370 kernel/locking/lockdep.c:5705 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] br_ip6_multicast_query net/bridge/br_multicast.c:3518 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] br_multicast_rcv+0x202d/0x6850 net/bridge/br_multicast.c:3969 br_dev_xmit+0x726/0x16d0 net/bridge/br_device.c:89 __netdev_start_xmit include/linux/netdevice.h:4915 [inline] netdev_start_xmit include/linux/netdevice.h:4929 [inline] xmit_one net/core/dev.c:3578 [inline] dev_hard_start_xmit+0x187/0x700 net/core/dev.c:3594 __dev_queue_xmit+0x2c57/0x3c10 net/core/dev.c:4244 dev_queue_xmit include/linux/netdevice.h:3085 [inline] vlan_dev_hard_start_xmit+0x1bc/0x5c0 net/8021q/vlan_dev.c:125 __netdev_start_xmit include/linux/netdevice.h:4915 [inline] netdev_start_xmit include/linux/netdevice.h:4929 [inline] xmit_one net/core/dev.c:3578 [inline] dev_hard_start_xmit+0x187/0x700 net/core/dev.c:3594 __dev_queue_xmit+0x2c57/0x3c10 net/core/dev.c:4244 dev_queue_xmit include/linux/netdevice.h:3085 [inline] br_dev_queue_push_xmit+0x26e/0x7b0 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:303 [inline] __br_multicast_send_query+0x11c6/0x3c10 net/bridge/br_multicast.c:1804 br_multicast_send_query+0x266/0x4b0 net/bridge/br_multicast.c:1883 br_multicast_port_query_expired+0x2c3/0x360 net/bridge/br_multicast.c:1908 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700 expire_timers+0x234/0x330 kernel/time/timer.c:1751 __run_timers kernel/time/timer.c:2022 [inline] __run_timers kernel/time/timer.c:1995 [inline] run_timer_softirq+0x326/0x910 kernel/time/timer.c:2035 __do_softirq+0x1d4/0x905 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x114/0x190 kernel/softirq.c:650 irq_exit_rcu+0x9/0x20 kernel/softirq.c:662 sysvec_apic_timer_interrupt+0x49/0xc0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0033:0x7f1e4376e460 Code: c9 ba 01 00 00 00 48 8d 3d 91 cf 00 00 48 89 fe e8 35 0b ff ff 48 89 c3 48 85 c0 74 c6 48 8b 05 0e 59 01 00 31 ff 48 8b 50 20 <0f> b7 70 38 48 01 c2 66 89 b3 b8 02 00 00 48 89 93 a8 02 00 00 48 RSP: 002b:00007ffebbb36740 EFLAGS: 00000246 RAX: 00007ffebbbbe000 RBX: 00007f1e43785850 RCX: 00007f1e43785bc0 RDX: 0000000000000040 RSI: 00007f1e43784ab0 RDI: 0000000000000000 RBP: 00007ffebbb369e0 R08: 0000000000000000 R09: 0000000000000000 R10: 00007f1e43785df8 R11: 00007f1e4377b3d4 R12: 0000000070000022 R13: 00000000effffef5 R14: 0000000000000000 R15: 00007f1e437852a0