rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=6357, q=64) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294953801-4294943298), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.4 R running task 24480 8189 8188 0x0000400a Call Trace: sched_show_task+0x40f/0x560 kernel/sched/core.c:5954 print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline] check_cpu_stall kernel/rcu/tree_stall.h:538 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0x1861/0x1ad0 kernel/rcu/tree.c:2271 update_process_times+0x12d/0x180 kernel/time/timer.c:1726 tick_sched_handle kernel/time/tick-sched.c:167 [inline] tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1514 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1576 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1638 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:check_kcov_mode kernel/kcov.c:79 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:102 Code: 64 02 3b 00 5b 5d c3 cc 48 8b 04 24 65 48 8b 0c 25 c0 1d 02 00 65 8b 15 b8 81 8b 7e f7 c2 00 01 1f 00 75 2c 8b 91 80 13 00 00 <83> fa 02 75 21 48 8b 91 88 13 00 00 48 8b 32 48 8d 7e 01 8b 89 84 RSP: 0018:ffffc900025878f0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81487326 RBX: ffffea0001af08c0 RCX: ffff888095c32300 RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea0001af08c0 RBP: ffffc90002587918 R08: 000000000003a768 R09: ffffed101327d327 R10: ffffed101327d327 R11: 0000000000000000 R12: ffff88806bc1fc20 R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff8880993e9928 free_thread_stack+0x168/0x590 kernel/fork.c:280 release_task_stack kernel/fork.c:440 [inline] put_task_stack+0xa3/0x130 kernel/fork.c:451 finish_task_switch+0x3f1/0x550 kernel/sched/core.c:3256 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x9a8/0xcc0 kernel/sched/core.c:4081 preempt_schedule_irq+0xc1/0x140 kernel/sched/core.c:4338 retint_kernel+0x1b/0x2b RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline] RIP: 0010:kfree+0x1a3/0x200 mm/slab.c:3758 Code: 48 83 3d 67 19 59 07 00 74 68 4c 89 f7 57 9d 0f 1f 44 00 00 eb 19 e8 ec b7 ca ff 48 83 3d 4c 19 59 07 00 74 51 4c 89 f7 57 9d <0f> 1f 44 00 00 5b 41 5c 41 5e 41 5f 5d c3 48 ff c9 48 89 c8 e9 c8 RSP: 0018:ffffc90002587b78 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: ffff888095c32b94 RBX: ffff8880aa800a80 RCX: ffff888095c32300 RDX: 0000000000000000 RSI: ffffffff86380c36 RDI: 0000000000000286 RBP: ffffc90002587b98 R08: ffff888095c32b58 R09: ffffc90002587974 R10: 000000000000000c R11: 0000000000000000 R12: ffff8880968be400 R13: 0000000000000000 R14: 0000000000000286 R15: ffffffff86380c36 skb_free_head net/core/skbuff.c:591 [inline] skb_release_data+0x726/0x8c0 net/core/skbuff.c:611 skb_release_all net/core/skbuff.c:665 [inline] __kfree_skb+0x59/0x1c0 net/core/skbuff.c:679 consume_skb+0x72/0x110 net/core/skbuff.c:838 skb_free_datagram+0x28/0xd0 net/core/datagram.c:328 netlink_recvmsg+0x5b1/0xfb0 net/netlink/af_netlink.c:1996 sock_recvmsg_nosec net/socket.c:873 [inline] sock_recvmsg net/socket.c:891 [inline] __sys_recvfrom+0x328/0x4b0 net/socket.c:2042 __do_sys_recvfrom net/socket.c:2060 [inline] __se_sys_recvfrom net/socket.c:2056 [inline] __x64_sys_recvfrom+0xe5/0x100 net/socket.c:2056 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41425d Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 8b 05 1e 42 66 00 85 c0 75 3e 45 31 c9 45 31 c0 4c 63 d1 48 63 ff b8 2d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0b c3 66 2e 0f 1f 84 00 00 00 00 00 48 c7 c2 RSP: 002b:00007ffce5a90f18 EFLAGS: 00000246 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 0000000000a72200 RCX: 000000000041425d RDX: 0000000000000400 RSI: 0000000000a72250 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000a72250 R15: 0000000000000003 rcu: rcu_preempt kthread starved for 10547 jiffies! g6357 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29032 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x9a0/0xcc0 kernel/sched/core.c:4081 schedule+0x181/0x210 kernel/sched/core.c:4155 schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0xed8/0x1770 kernel/rcu/tree.c:1821 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352