rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (1 GPs behind) idle=b8a/1/0x4000000000000002 softirq=12441/12442 fqs=1 (t=10501 jiffies g=6393 q=388) rcu: rcu_preempt kthread starved for 10500 jiffies! g6393 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29104 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 NMI backtrace for cpu 1 CPU: 1 PID: 8135 Comm: blkid Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaf/0x1a0 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x174/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x15a/0x220 kernel/rcu/tree_stall.h:254 print_cpu_stall kernel/rcu/tree_stall.h:455 [inline] check_cpu_stall kernel/rcu/tree_stall.h:529 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq+0xe25/0x1ad0 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:__read_once_size include/linux/compiler.h:199 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:70 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x50 kernel/kcov.c:102 Code: cc 07 48 89 de e8 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 RSP: 0018:ffffc90002247720 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81487326 RBX: ffffea00025b8a00 RCX: ffff88809b0c4340 RDX: 0000000000000001 RSI: 00000000fffffffc RDI: ffffea00025b8a00 RBP: ffffc90002247748 R08: dffffc0000000000 R09: fffffbfff120248a R10: fffffbfff120248a R11: 0000000000000000 R12: ffff88808b674aa0 R13: dffffc0000000000 R14: 00000000fffffffc R15: ffff888098e51868 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:kmem_cache_free+0xc8/0xf0 mm/slab.c:3695 Code: 58 07 00 74 42 4c 89 f7 57 9d 0f 1f 44 00 00 e8 0e 98 ca ff eb 19 e8 a7 95 ca ff 48 83 3d 07 f7 58 07 00 74 24 4c 89 f7 57 9d <0f> 1f 44 00 00 4c 89 e7 4c 89 fe e8 58 01 00 00 5b 41 5c 41 5e 41 RSP: 0018:ffffc900022479a0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: ffff88809b0c4bd4 RBX: ffff8880aa812a80 RCX: ffff88809b0c4340 RDX: 0000000000000000 RSI: ffffffff81a3c074 RDI: 0000000000000286 RBP: ffffc900022479c0 R08: ffff88809b0c4b98 R09: ffffc900022477d4 R10: 0000000000000012 R11: 0000000000000000 R12: ffffffff81a3c074 R13: ffffea00022d8440 R14: 0000000000000286 R15: ffff8880a8ddf580 ptlock_free+0x44/0x50 mm/memory.c:4756 pgtable_pte_page_dtor include/linux/mm.h:1951 [inline] ___pte_free_tlb+0x2c/0x190 arch/x86/mm/pgtable.c:48 __pte_free_tlb arch/x86/include/asm/pgalloc.h:60 [inline] free_pte_range mm/memory.c:218 [inline] free_pmd_range mm/memory.c:236 [inline] free_pud_range mm/memory.c:270 [inline] free_p4d_range mm/memory.c:304 [inline] free_pgd_range+0x7ff/0xea0 mm/memory.c:384 free_pgtables+0x2c8/0x300 mm/memory.c:416 exit_mmap+0x28a/0x530 mm/mmap.c:3141 __mmput+0x120/0x3a0 kernel/fork.c:1082 mmput+0x5d/0x70 kernel/fork.c:1103 exit_mm+0x50a/0x590 kernel/exit.c:485 do_exit+0x544/0x2020 kernel/exit.c:784 do_group_exit+0x15c/0x2b0 kernel/exit.c:895 __do_sys_exit_group+0x17/0x20 kernel/exit.c:906 __se_sys_exit_group+0x14/0x20 kernel/exit.c:904 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:904 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7ff122b9e1e8 Code: Bad RIP value. RSP: 002b:00007ffe5f5ad3e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007ff122b9e1e8 RDX: 0000000000000002 RSI: 000000000000003c RDI: 0000000000000002 RBP: 00007ff122e73840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007ff122e79740 R11: 0000000000000246 R12: 00007ff122e73840 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000