============================= 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.3.91/4472: #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_pte_range mm/memory.c:1342 [inline] #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_pmd_range mm/memory.c:1505 [inline] #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_pud_range mm/memory.c:1534 [inline] #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_p4d_range mm/memory.c:1555 [inline] #0: ffff0000cef37d38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: unmap_page_range+0x6d0/0x1958 mm/memory.c:1576 #1: ffff8000143311e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #2: ffff0000da0a4148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: qdisc_run+0x2c/0x1f8 include/net/pkt_sched.h:131 #3: ffff0000da0a4108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #3: ffff0000da0a4108 (&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: 4472 Comm: syz.3.91 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 cake_dequeue+0x1800/0x3afc net/sched/sch_cake.c:2189 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 __kasan_check_read+0x1c/0x54 mm/kasan/shadow.c:31 instrument_atomic_read include/linux/instrumented.h:71 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline] page_mapcount include/linux/mm.h:877 [inline] zap_pte_range mm/memory.c:1385 [inline] zap_pmd_range mm/memory.c:1505 [inline] zap_pud_range mm/memory.c:1534 [inline] zap_p4d_range mm/memory.c:1555 [inline] unmap_page_range+0xc24/0x1958 mm/memory.c:1576 unmap_single_vma+0x13c/0x1e4 mm/memory.c:1621 unmap_vmas+0x104/0x200 mm/memory.c:1653 exit_mmap+0x2a8/0x4e0 mm/mmap.c:3204 __mmput+0xec/0x3b8 kernel/fork.c:1127 mmput+0x80/0xc8 kernel/fork.c:1148 exit_mm+0x4a0/0x684 kernel/exit.c:550 do_exit+0x4e4/0x1f58 kernel/exit.c:861 do_group_exit+0x100/0x268 kernel/exit.c:996 get_signal+0x73c/0x1340 kernel/signal.c:2900 do_signal arch/arm64/kernel/signal.c:893 [inline] do_notify_resume+0x35c/0x3128 arch/arm64/kernel/signal.c:946 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