rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (11 ticks this GP) idle=d06/0/0x3 softirq=11716/11716 fqs=0 (detected by 0, t=14483 jiffies, g=12109, q=110) ============================================ WARNING: possible recursive locking detected 5.13.0-rc6-syzkaller #0 Not tainted -------------------------------------------- syz-executor951/8952 is trying to acquire lock: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0xd0/0x3f0 kernel/rcu/tree_stall.h:336 but task is already holding lock: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:542 [inline] ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:708 [inline] ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3911 [inline] ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq+0xc63/0x2080 kernel/rcu/tree.c:2649 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-executor951/8952: #0: ffffffff8d6a9228 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline] #0: ffffffff8d6a9228 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3f9/0xb70 net/core/rtnetlink.c:5571 #1: ffff888031f82108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline] #1: ffff888031f82108 (&sch->q.lock){+.-.}-{2:2}, at: dev_reset_queue+0x8a/0x130 net/sched/sch_generic.c:1226 #2: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:542 [inline] #2: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:708 [inline] #2: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3911 [inline] #2: ffffffff8bf82218 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq+0xc63/0x2080 kernel/rcu/tree.c:2649 stack backtrace: CPU: 0 PID: 8952 Comm: syz-executor951 Not tainted 5.13.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_deadlock_bug kernel/locking/lockdep.c:2831 [inline] check_deadlock kernel/locking/lockdep.c:2874 [inline] validate_chain kernel/locking/lockdep.c:3663 [inline] __lock_acquire.cold+0x22f/0x3b4 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __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:336 print_other_cpu_stall kernel/rcu/tree_stall.h:560 [inline] check_cpu_stall kernel/rcu/tree_stall.h:708 [inline] rcu_pending kernel/rcu/tree.c:3911 [inline] rcu_sched_clock_irq+0x1a79/0x2080 kernel/rcu/tree.c:2649 update_process_times+0x16d/0x200 kernel/time/timer.c:1796 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1374 __run_hrtimer kernel/time/hrtimer.c:1537 [inline] __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0x146/0x540 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:647 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 kernel/locking/spinlock.c:191 Code: 74 24 10 e8 ca fa 3c f8 48 89 ef e8 62 73 3d f8 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 d3 69 31 f8 65 8b 05 cc 6b e4 76 85 c0 74 0a 5b 5d c3 e8 10 65 RSP: 0018:ffffc90002817260 EFLAGS: 00000206 RAX: 0000000000000002 RBX: 0000000000000200 RCX: 1ffffffff2058112 RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000001 RBP: ffff8880b9d26380 R08: 0000000000000001 R09: ffffffff9026f977 R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000246 R14: ffff8880b9d26580 R15: dffffc0000000000 unlock_hrtimer_base kernel/time/hrtimer.c:915 [inline] hrtimer_try_to_cancel kernel/time/hrtimer.c:1188 [inline] hrtimer_try_to_cancel+0x14c/0x1e0 kernel/time/hrtimer.c:1168 hrtimer_cancel+0x13/0x40 kernel/time/hrtimer.c:1295 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+0x551/0xc30 net/sched/sch_generic.c:1294 dev_deactivate+0xe9/0x1b0 net/sched/sch_generic.c:1317 qdisc_graft+0xdc1/0x1260 net/sched/sch_api.c:1055 tc_modify_qdisc+0xb5a/0x1a50 net/sched/sch_api.c:1674 rtnetlink_rcv_msg+0x44e/0xb70 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+0x856/0xd90 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:702 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:722 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2385 ___sys_sendmsg+0xf3/0x170 net/socket.c:2439 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2468 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x443ba9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffde5751ec8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443ba9 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d R10: 000000000000000d R11: 0000000000000246 R12: 00007ffde5751ee0 R13: 00000000000f4240 R14: 000000000006ce54 R15: 00007ffde5751ed4