============================================ WARNING: possible recursive locking detected 6.1.84-syzkaller #0 Not tainted -------------------------------------------- syz-executor.1/8470 is trying to acquire lock: ffff0000cc77a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000cc77a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3884 [inline] ffff0000cc77a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1e3c/0x38d8 net/core/dev.c:4259 but task is already holding lock: ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline] ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b4/0x38d8 net/core/dev.c:4259 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** May be due to missing lock nesting notation 9 locks held by syz-executor.1/8470: #0: ffff0000d94360e0 (&type->s_umount_key#46/1){+.+.}-{3:3}, at: alloc_super+0x1b4/0x824 fs/super.c:228 #1: ffff0000cb018938 ((wq_completion)xfs_iwalk-8470){+.+.}-{0:0}, at: __flush_workqueue+0x120/0x11c4 kernel/workqueue.c:2812 #2: ffff800008017c80 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #2: ffff800008017c80 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd0/0xa1c kernel/time/timer.c:1494 #3: ffff800015a14ca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #4: ffff800015a14ca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #5: ffff800015a14d00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #6: ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #6: ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #6: ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline] #6: ffff0000edbc7258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b4/0x38d8 net/core/dev.c:4259 #7: ffff800015a14ca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #8: ffff800015a14d00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 stack backtrace: CPU: 1 PID: 8470 Comm: syz-executor.1 Not tainted 6.1.84-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 __lock_acquire+0x6310/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __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:351 [inline] __dev_xmit_skb net/core/dev.c:3884 [inline] __dev_queue_xmit+0x1e3c/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xc58/0x1198 net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x268 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x330/0x49c net/ipv4/ip_output.c:430 dst_output include/net/dst.h:444 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126 iptunnel_xmit+0x40c/0x8ec net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x19a0/0x28bc net/ipv4/ip_tunnel.c:840 __gre_xmit net/ipv4/ip_gre.c:469 [inline] gre_tap_xmit+0x400/0x5e0 net/ipv4/ip_gre.c:746 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3854 [inline] __dev_queue_xmit+0x1658/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip6_finish_output2+0xd78/0x1a88 net/ipv6/ip6_output.c:134 __ip6_finish_output net/ipv6/ip6_output.c:201 [inline] ip6_finish_output+0x5a4/0x940 net/ipv6/ip6_output.c:212 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip6_output+0x270/0x594 net/ipv6/ip6_output.c:233 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xc38/0x179c net/ipv6/ndisc.c:509 ndisc_send_rs+0x47c/0x5d4 net/ipv6/ndisc.c:719 addrconf_rs_timer+0x300/0x58c net/ipv6/addrconf.c:3961 call_timer_fn+0x1c0/0xa1c kernel/time/timer.c:1504 expire_timers kernel/time/timer.c:1549 [inline] __run_timers+0x554/0x718 kernel/time/timer.c:1820 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1833 __do_softirq+0x314/0xe38 kernel/softirq.c:571 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:893 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85 invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0x264/0x4d4 kernel/softirq.c:650 irq_exit_rcu+0x14/0x84 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:581 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] lock_acquire+0x2ac/0x7cc kernel/locking/lockdep.c:5665 __flush_workqueue+0x14c/0x11c4 kernel/workqueue.c:2812 drain_workqueue+0xb8/0x32c kernel/workqueue.c:2977 destroy_workqueue+0x80/0xa34 kernel/workqueue.c:4423 xfs_pwork_destroy+0x40/0x94 fs/xfs/xfs_pwork.c:105 xfs_iwalk_threaded+0x4f0/0x584 fs/xfs/xfs_iwalk.c:689 xfs_qm_quotacheck+0x224/0x58c fs/xfs/xfs_qm.c:1314 xfs_qm_mount_quotas+0x2c4/0x590 fs/xfs/xfs_qm.c:1437 xfs_mountfs+0x1368/0x18fc fs/xfs/xfs_mount.c:945 xfs_fs_fill_super+0xe28/0x1080 fs/xfs/xfs_super.c:1681 get_tree_bdev+0x360/0x54c fs/super.c:1355 xfs_fs_get_tree+0x28/0x38 fs/xfs/xfs_super.c:1728 vfs_get_tree+0x90/0x274 fs/super.c:1562 do_new_mount+0x278/0x8fc fs/namespace.c:3051 path_mount+0x590/0xe5c fs/namespace.c:3381 do_mount fs/namespace.c:3394 [inline] __do_sys_mount fs/namespace.c:3602 [inline] __se_sys_mount fs/namespace.c:3579 [inline] __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3579 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585