============================================ WARNING: possible recursive locking detected 6.2.0-rc3-syzkaller-16369-g358a161a6a9e #0 Not tainted -------------------------------------------- dhcpcd-run-hook/4558 is trying to acquire lock: ffff0000c4525338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000c4525338 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_query net/bridge/br_multicast.c:3351 [inline] ffff0000c4525338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_ipv6_rcv net/bridge/br_multicast.c:3747 [inline] ffff0000c4525338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_rcv+0x5f4/0x2c38 net/bridge/br_multicast.c:3802 but task is already holding lock: ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1752 [inline] ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_port_query_expired+0x38/0x160 net/bridge/br_multicast.c:1780 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 6 locks held by dhcpcd-run-hook/4558: #0: ffff0000c0e74b88 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline] #0: ffff0000c0e74b88 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0xa0/0x1d0 mm/util.c:518 #1: ffff800008003e20 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:31 [inline] #1: ffff800008003e20 ((&pmctx->ip6_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0x54/0x144 kernel/time/timer.c:1690 #2: ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #2: ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1752 [inline] #2: ffff0000c4527338 (&br->multicast_lock){+.-.}-{2:2}, at: br_ip6_multicast_port_query_expired+0x38/0x160 net/bridge/br_multicast.c:1780 #3: ffff80000d645548 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:324 #4: ffff80000d645548 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:324 #5: ffff80000d645520 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:324 stack backtrace: CPU: 0 PID: 4558 Comm: dhcpcd-run-hook Not tainted 6.2.0-rc3-syzkaller-16369-g358a161a6a9e #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 __lock_acquire+0x808/0x3084 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5668 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] br_ip6_multicast_query net/bridge/br_multicast.c:3351 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:3747 [inline] br_multicast_rcv+0x5f4/0x2c38 net/bridge/br_multicast.c:3802 br_dev_xmit+0x4ac/0x924 net/bridge/br_device.c:89 __netdev_start_xmit include/linux/netdevice.h:4865 [inline] netdev_start_xmit include/linux/netdevice.h:4879 [inline] xmit_one net/core/dev.c:3583 [inline] dev_hard_start_xmit+0xd4/0x1ec net/core/dev.c:3599 __dev_queue_xmit+0x83c/0xdb8 net/core/dev.c:4249 dev_queue_xmit include/linux/netdevice.h:3035 [inline] vlan_dev_hard_start_xmit+0x110/0x260 net/8021q/vlan_dev.c:124 __netdev_start_xmit include/linux/netdevice.h:4865 [inline] netdev_start_xmit include/linux/netdevice.h:4879 [inline] xmit_one net/core/dev.c:3583 [inline] dev_hard_start_xmit+0xd4/0x1ec net/core/dev.c:3599 __dev_queue_xmit+0x83c/0xdb8 net/core/dev.c:4249 dev_queue_xmit include/linux/netdevice.h:3035 [inline] br_dev_queue_push_xmit+0x318/0x388 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:302 [inline] __br_multicast_send_query+0xf60/0x11d0 net/bridge/br_multicast.c:1656 br_multicast_send_query+0x254/0x298 net/bridge/br_multicast.c:1735 br_multicast_port_query_expired net/bridge/br_multicast.c:1760 [inline] br_ip6_multicast_port_query_expired+0x140/0x160 net/bridge/br_multicast.c:1780 call_timer_fn+0x90/0x144 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x284/0x384 kernel/time/timer.c:2022 run_timer_softirq+0x34/0x5c kernel/time/timer.c:2035 _stext+0x168/0x37c ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80 call_on_irq_stack+0x2c/0x54 arch/arm64/kernel/entry.S:892 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85 invoke_softirq+0x70/0xbc kernel/softirq.c:452 __irq_exit_rcu+0xf0/0x140 kernel/softirq.c:650 irq_exit_rcu+0x10/0x40 kernel/softirq.c:662 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline] el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:580 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] put_cpu_partial+0x164/0x1b4 mm/slub.c:2710 __slab_free+0x184/0x250 mm/slub.c:3653 do_slab_free mm/slub.c:3731 [inline] slab_free mm/slub.c:3788 [inline] kmem_cache_free+0x2a8/0x3a4 mm/slub.c:3809 vm_area_free+0x38/0xe8 kernel/fork.c:485 remove_vma mm/mmap.c:144 [inline] remove_mt mm/mmap.c:2163 [inline] do_mas_align_munmap+0x710/0x894 mm/mmap.c:2443 do_mas_munmap mm/mmap.c:2498 [inline] mmap_region+0x434/0x1064 mm/mmap.c:2546 do_mmap+0x6e0/0xa28 mm/mmap.c:1411 vm_mmap_pgoff+0xe8/0x1d0 mm/util.c:520 ksys_mmap_pgoff+0xa0/0x278 mm/mmap.c:1457 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0x58/0x6c arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall arch/arm64/kernel/syscall.c:52 [inline] el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584