============================= WARNING: suspicious RCU usage 5.15.185-syzkaller #0 Not tainted ----------------------------- net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 5 locks held by syz-executor/4040: #0: ffff0000d51740e0 (&type->s_umount_key#50){+.+.}-{3:3}, at: deactivate_super+0xf0/0x118 fs/super.c:365 #1: ffff8000143311e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #2: ffff0000d7d6d948 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: qdisc_run+0x2c/0x1f8 include/net/pkt_sched.h:131 #3: ffff0000d7d6d908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #3: ffff0000d7d6d908 (&sch->q.lock){+.-.}-{2:2}, at: sch_direct_xmit+0x1e4/0x3bc net/sched/sch_generic.c:354 #4: ffff8000143311e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:311 stack backtrace: CPU: 0 PID: 4040 Comm: syz-executor Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 lockdep_rcu_suspicious+0x140/0x198 kernel/locking/lockdep.c:6574 qdisc_lookup+0xc8/0x64c net/sched/sch_api.c:304 qdisc_tree_reduce_backlog+0x204/0x4a0 net/sched/sch_api.c:800 codel_qdisc_dequeue+0x1194/0x1b3c net/sched/sch_codel.c:102 qdisc_peek_dequeued+0x78/0x1ec include/net/sch_generic.h:1115 tbf_dequeue+0x90/0xc5c net/sched/sch_tbf.c:265 dequeue_skb net/sched/sch_generic.c:292 [inline] qdisc_restart net/sched/sch_generic.c:397 [inline] __qdisc_run+0x1bc/0x1170 net/sched/sch_generic.c:415 qdisc_run+0x40/0x1f8 include/net/pkt_sched.h:132 net_tx_action+0x630/0x81c net/core/dev.c:5128 handle_softirqs+0x344/0xbf0 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline] invoke_softirq kernel/softirq.c:457 [inline] __irq_exit_rcu+0x240/0x440 kernel/softirq.c:659 irq_exit+0x14/0x88 kernel/softirq.c:683 handle_domain_irq+0x14c/0x1fc kernel/irq/irqdesc.c:711 gic_handle_irq+0x78/0x1c8 drivers/irqchip/irq-gic-v3.c:765 call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:899 do_interrupt_handler+0x6c/0x88 arch/arm64/kernel/entry-common.c:267 el1_interrupt+0x30/0x58 arch/arm64/kernel/entry-common.c:454 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] lockdep_unregister_key+0x30c/0x38c kernel/locking/lockdep.c:6332 wq_unregister_lockdep kernel/workqueue.c:3518 [inline] destroy_workqueue+0x780/0x9ac kernel/workqueue.c:4485 xfs_destroy_mount_workqueues+0x74/0xdc fs/xfs/xfs_super.c:574 xfs_fs_put_super+0x1d4/0x250 fs/xfs/xfs_super.c:1102 generic_shutdown_super+0x130/0x2f0 fs/super.c:475 kill_block_super+0x70/0xdc fs/super.c:1427 deactivate_locked_super+0xb8/0x13c fs/super.c:335 deactivate_super+0xf8/0x118 fs/super.c:366 cleanup_mnt+0x3a4/0x458 fs/namespace.c:1139 __cleanup_mnt+0x20/0x30 fs/namespace.c:1146 task_work_run+0x12c/0x1e0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x24b4/0x3128 arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584