rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (10 ticks this GP) idle=3ae/1/0x4000000000000000 softirq=8207/8207 fqs=0 (detected by 1, t=10563 jiffies, g=10445, q=543) ============================================ WARNING: possible recursive locking detected 5.14.0-rc5-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/5969 is trying to acquire lock: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0xd0/0x3f0 kernel/rcu/tree_stall.h:337 but task is already holding lock: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:543 [inline] ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:709 [inline] ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3922 [inline] ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq+0xc9a/0x20c0 kernel/rcu/tree.c:2641 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rcu_node_0); lock(rcu_node_0); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor.0/5969: #0: ffffffff8d0cd4e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline] #0: ffffffff8d0cd4e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3be/0xb80 net/core/rtnetlink.c:5571 #1: ffff88802d07a908 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] #1: ffff88802d07a908 (&sch->q.lock){+.-.}-{2:2}, at: dev_reset_queue+0x8a/0x130 net/sched/sch_generic.c:1226 #2: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:543 [inline] #2: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:709 [inline] #2: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3922 [inline] #2: ffffffff8b985018 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq+0xc9a/0x20c0 kernel/rcu/tree.c:2641 stack backtrace: CPU: 1 PID: 5969 Comm: syz-executor.0 Not tainted 5.14.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_deadlock_bug kernel/locking/lockdep.c:2944 [inline] check_deadlock kernel/locking/lockdep.c:2987 [inline] validate_chain kernel/locking/lockdep.c:3776 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159 rcu_dump_cpu_stacks+0xd0/0x3f0 kernel/rcu/tree_stall.h:337 print_other_cpu_stall kernel/rcu/tree_stall.h:561 [inline] check_cpu_stall kernel/rcu/tree_stall.h:709 [inline] rcu_pending kernel/rcu/tree.c:3922 [inline] rcu_sched_clock_irq+0x1cc6/0x20c0 kernel/rcu/tree.c:2641 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x13/0x60 kernel/kcov.c:196 Code: 00 4d 8b 03 48 0f bd ca 49 8b 45 00 48 63 c9 e9 64 ff ff ff 0f 1f 00 65 8b 05 39 37 8c 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 <65> 48 8b 14 25 00 f0 01 00 a9 00 01 ff 00 74 0e 85 c9 74 35 8b 82 RSP: 0018:ffffc90001a9f210 EFLAGS: 00000246 RAX: 0000000000000201 RBX: 00000000028311d6 RCX: 0000000000000000 RDX: ffff88801a873880 RSI: ffffffff816539ca RDI: ffff8880b9c26608 RBP: ffff8880b9c265c0 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff81653947 R11: 0000000000000000 R12: 0000000000000001 R13: ffff88802d07ab40 R14: dffffc0000000000 R15: 0000000000000010 hrtimer_active+0x17a/0x1f0 kernel/time/hrtimer.c:1615 hrtimer_try_to_cancel+0x21/0x1e0 kernel/time/hrtimer.c:1328 hrtimer_cancel+0x13/0x40 kernel/time/hrtimer.c:1443 taprio_reset+0x72/0x280 net/sched/sch_taprio.c:1622 qdisc_reset+0xdb/0x730 net/sched/sch_generic.c:977 dev_reset_queue+0x92/0x130 net/sched/sch_generic.c:1228 netdev_for_each_tx_queue include/linux/netdevice.h:2337 [inline] dev_deactivate_many+0x51c/0xc40 net/sched/sch_generic.c:1294 dev_deactivate+0xe9/0x1b0 net/sched/sch_generic.c:1317 qdisc_graft+0xdac/0x1260 net/sched/sch_api.c:1055 tc_modify_qdisc+0xba4/0x1a60 net/sched/sch_api.c:1674 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5574 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:723 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2392 ___sys_sendmsg+0xf3/0x170 net/socket.c:2446 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2475 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665d9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f141db04188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffd8eafafcf R14: 00007f141db04300 R15: 0000000000022000