============================================ WARNING: possible recursive locking detected 6.12.0-rc7-syzkaller-00012-g3022e9d00ebe #0 Not tainted -------------------------------------------- kworker/1:4/5849 is trying to acquire lock: ffff8880276fd918 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880276fd918 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4371 [inline] ffff8880276fd918 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1a7/0x5d0 net/sched/sch_generic.c:341 but task is already holding lock: ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4371 [inline] ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x17ca/0x3ed0 net/core/dev.c:4428 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&qdisc_xmit_lock_key#2); lock(&qdisc_xmit_lock_key#2); *** DEADLOCK *** May be due to missing lock nesting notation 10 locks held by kworker/1:4/5849: #0: ffff88802f90f548 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88802f90f548 ((wq_completion)mld){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310 #1: ffffc90003d27d00 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc90003d27d00 ((work_completion)(&(&idev->mc_ifc_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310 #2: ffff888078919538 (&idev->mc_lock){+.+.}-{3:3}, at: mld_ifc_work+0x2d/0xd90 net/ipv6/mcast.c:2650 #3: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #3: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: mld_sendpack+0x1e8/0xdb0 net/ipv6/mcast.c:1791 #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #4: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x75c/0x1730 net/ipv6/ip6_output.c:126 #5: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:901 [inline] #5: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2da/0x3ed0 net/core/dev.c:4357 #6: ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #6: ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4371 [inline] #6: ffff88805a40cd18 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x17ca/0x3ed0 net/core/dev.c:4428 #7: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline] #7: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #7: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x45f/0x1390 net/ipv4/ip_output.c:229 #8: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:901 [inline] #8: ffffffff8e937e00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2da/0x3ed0 net/core/dev.c:4357 #9: ffff88807e8ea258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #9: ffff88807e8ea258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:197 [inline] #9: ffff88807e8ea258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3812 [inline] #9: ffff88807e8ea258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: __dev_queue_xmit+0x1364/0x3ed0 net/core/dev.c:4398 stack backtrace: CPU: 1 UID: 0 PID: 5849 Comm: kworker/1:4 Not tainted 6.12.0-rc7-syzkaller-00012-g3022e9d00ebe #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Workqueue: mld mld_ifc_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3037 check_deadlock kernel/locking/lockdep.c:3089 [inline] validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3891 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __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:351 [inline] __netif_tx_lock include/linux/netdevice.h:4371 [inline] sch_direct_xmit+0x1a7/0x5d0 net/sched/sch_generic.c:341 __dev_xmit_skb net/core/dev.c:3825 [inline] __dev_queue_xmit+0x1a2d/0x3ed0 net/core/dev.c:4398 NF_HOOK+0x3a5/0x450 include/linux/netfilter.h:314 arp_solicit+0xc64/0xe90 net/ipv4/arp.c:392 neigh_probe net/core/neighbour.c:1077 [inline] __neigh_event_send+0xed4/0x15b0 net/core/neighbour.c:1244 neigh_event_send_probe include/net/neighbour.h:466 [inline] neigh_event_send include/net/neighbour.h:472 [inline] neigh_resolve_output+0x1b5/0x740 net/core/neighbour.c:1549 neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xe70/0x1390 net/ipv4/ip_output.c:236 iptunnel_xmit+0x540/0x9b0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1fb0/0x26a0 net/ipv4/ip_tunnel.c:858 __gre_xmit net/ipv4/ip_gre.c:484 [inline] ipgre_xmit+0x8d6/0xc90 net/ipv4/ip_gre.c:688 __netdev_start_xmit include/linux/netdevice.h:4928 [inline] netdev_start_xmit include/linux/netdevice.h:4937 [inline] xmit_one net/core/dev.c:3588 [inline] dev_hard_start_xmit+0x27a/0x7e0 net/core/dev.c:3604 __dev_queue_xmit+0x1b11/0x3ed0 net/core/dev.c:4432 neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0x1001/0x1730 net/ipv6/ip6_output.c:141 ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:226 NF_HOOK+0x9e/0x430 include/linux/netfilter.h:314 mld_sendpack+0x843/0xdb0 net/ipv6/mcast.c:1819 mld_send_cr net/ipv6/mcast.c:2120 [inline] mld_ifc_work+0x7d9/0xd90 net/ipv6/mcast.c:2651 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244