============================= 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.4.128/4660: #0: ffff0000d4c9c0e0 (&type->s_umount_key#57/1){+.+.}-{3:3}, at: alloc_super+0x1a8/0x824 fs/super.c:229 #1: ffff8000143311e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:311 #2: ffff0000cf362148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: qdisc_run+0x2c/0x1f8 include/net/pkt_sched.h:131 #3: ffff0000cf362108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #3: ffff0000cf362108 (&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: 1 PID: 4660 Comm: syz.4.128 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 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] seqcount_lockdep_reader_access+0x21c/0x2c4 include/linux/seqlock.h:105 timekeeping_get_delta kernel/time/timekeeping.c:254 [inline] timekeeping_get_ns kernel/time/timekeeping.c:388 [inline] ktime_get+0xa8/0x268 kernel/time/timekeeping.c:831 ktime_get_ns include/linux/timekeeping.h:154 [inline] bio_issue_init include/linux/blk_types.h:207 [inline] blkcg_bio_issue_init include/linux/blk-cgroup.h:537 [inline] submit_bio_checks+0xba0/0x17c0 block/blk-core.c:884 __submit_bio+0x420/0x624 block/blk-core.c:911 __submit_bio_noacct_mq block/blk-core.c:997 [inline] submit_bio_noacct+0x52c/0x624 block/blk-core.c:1027 submit_bio+0x374/0x5e0 block/blk-core.c:1089 __submit_bio+0x7e8/0xcb8 fs/f2fs/data.c:494 f2fs_submit_page_bio+0x464/0x680 fs/f2fs/data.c:688 f2fs_ra_meta_pages+0x5ac/0x80c fs/f2fs/checkpoint.c:282 build_sit_entries+0x1d0/0x155c fs/f2fs/segment.c:4525 f2fs_build_segment_manager+0x3484/0x44dc fs/f2fs/segment.c:5220 f2fs_fill_super+0x3d3c/0x5d84 fs/f2fs/super.c:4239 mount_bdev+0x264/0x358 fs/super.c:1400 f2fs_mount+0x44/0x58 fs/f2fs/super.c:4519 legacy_get_tree+0xd4/0x16c fs/fs_context.c:611 vfs_get_tree+0x90/0x274 fs/super.c:1530 do_new_mount+0x228/0x810 fs/namespace.c:3010 path_mount+0x5b4/0x1000 fs/namespace.c:3340 do_mount fs/namespace.c:3353 [inline] __do_sys_mount fs/namespace.c:3561 [inline] __se_sys_mount fs/namespace.c:3538 [inline] __arm64_sys_mount+0x514/0x5e4 fs/namespace.c:3538 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584