rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-....: (10499 ticks this GP) idle=c02/1/0x4000000000000002 softirq=14037/14037 fqs=2731 (t=10500 jiffies g=6669 q=1115) rcu: rcu_preempt kthread starved for 5019 jiffies! g6669 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 28984 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: 8513 Comm: syz-executor.0 Not tainted 5.5.0-rc5-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:1517 [inline] __hrtimer_run_queues+0x403/0x840 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x38c/0xda0 kernel/time/hrtimer.c:1641 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:free_thread_stack+0x18b/0x590 kernel/fork.c:284 Code: ff ff e8 28 04 00 00 43 80 3c 2e 00 74 08 4c 89 e7 e8 39 94 6a 00 49 8b 1c 24 48 83 c3 08 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 1b 94 6a 00 48 8b 1b e9 82 ff ff ff e8 be 2b 2e RSP: 0018:ffffc900026a76d8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 1ffff11011f71671 RBX: ffff88808fb8b388 RCX: ffff8880a87e2100 RDX: 0000000000000000 RSI: 00000000fffffffc RDI: ffffea00026f9240 RBP: ffffc900026a7710 R08: dffffc0000000000 R09: fffffbfff124248a R10: fffffbfff124248a R11: 0000000000000000 R12: ffff88808fb8b1a0 R13: dffffc0000000000 R14: 1ffff11011f71634 R15: ffff88808f2455f8 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:lock_acquire+0x1b2/0x250 kernel/locking/lockdep.c:4488 Code: c1 e8 03 42 80 3c 30 00 74 0c 48 c7 c7 68 95 2a 89 e8 02 7a 57 00 48 83 3d 92 e8 ce 07 00 0f 84 9c 00 00 00 48 8b 7d c0 57 9d <0f> 1f 44 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 44 89 RSP: 0018:ffffc900026a7928 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff12552ad RBX: 0000000000000000 RCX: ffffffff815c83e2 RDX: dffffc0000000000 RSI: 0000000000000008 RDI: 0000000000000286 RBP: ffffc900026a7980 R08: dffffc0000000000 R09: fffffbfff140cf1f R10: fffffbfff140cf1f R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8880aa008ad8 down_read+0x39/0x50 kernel/locking/rwsem.c:1495 inode_lock_shared include/linux/fs.h:801 [inline] lookup_slow fs/namei.c:1681 [inline] walk_component+0x2c2/0x5f0 fs/namei.c:1802 link_path_walk+0x75b/0x1410 fs/namei.c:2114 path_openat+0x139/0x4240 fs/namei.c:3536 do_filp_open+0x192/0x3d0 fs/namei.c:3567 do_sys_open+0x29f/0x560 fs/open.c:1097 __do_sys_open fs/open.c:1115 [inline] __se_sys_open fs/open.c:1110 [inline] __x64_sys_open+0x87/0x90 fs/open.c:1110 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x414cc0 Code: 05 48 3d 01 f0 ff ff 0f 83 2d 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 3d ad 37 66 00 00 75 14 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff RSP: 002b:00007ffe4a3cff48 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffe4a3cff74 RCX: 0000000000414cc0 RDX: 00007ffe4a3cff7a RSI: 0000000000080001 RDI: 00000000004c0a49 RBP: 00007ffe4a3cff70 R08: 0000000000000000 R09: 0000000000000004 R10: 0000000000000075 R11: 0000000000000246 R12: 00000000004c0a49 R13: 00007ffe4a3d0490 R14: 0000000000000000 R15: 00007ffe4a3d04a0