rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10500 ticks this GP) idle=3d6/1/0x4000000000000000 softirq=88641/88641 fqs=5 (t=10502 jiffies g=171121 q=208) rcu: rcu_preempt kthread starved for 10493 jiffies! g171121 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29120 10 2 0x00004000 Call Trace: context_switch kernel/sched/core.c:3430 [inline] __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4155 schedule+0xd0/0x2a0 kernel/sched/core.c:4230 schedule_timeout+0x148/0x250 kernel/time/timer.c:1897 rcu_gp_fqs_loop kernel/rcu/tree.c:1856 [inline] rcu_gp_kthread+0xae5/0x1b50 kernel/rcu/tree.c:2026 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 NMI backtrace for cpu 0 CPU: 0 PID: 1217 Comm: syz-executor.4 Not tainted 5.8.0-rc2-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+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x194/0x1cf kernel/rcu/tree_stall.h:320 print_cpu_stall kernel/rcu/tree_stall.h:553 [inline] check_cpu_stall kernel/rcu/tree_stall.h:627 [inline] rcu_pending kernel/rcu/tree.c:3471 [inline] rcu_sched_clock_irq.cold+0x5b3/0xccc kernel/rcu/tree.c:2486 update_process_times+0x25/0x60 kernel/time/timer.c:1726 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176 tick_sched_timer+0x108/0x290 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x1d5/0xfc0 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x32a/0x930 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x142/0x5e0 arch/x86/kernel/apic/apic.c:1097 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:50 [inline] sysvec_apic_timer_interrupt+0x128/0x220 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596 RIP: 0010:qdisc_root_sleeping include/net/sch_generic.h:519 [inline] RIP: 0010:pie_timer+0x6c/0x180 net/sched/sch_pie.c:427 Code: ea 03 80 3c 02 00 0f 85 03 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 40 49 8d 7c 24 10 48 89 fa 48 c1 ea 03 80 3c 02 00 <0f> 85 f3 00 00 00 4d 8b 64 24 10 49 81 c4 f0 00 00 00 4c 89 e7 e8 RSP: 0018:ffffc90000007d10 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffff88802a52a800 RCX: ffffffff816342c8 RDX: 1ffff1100ad2fc02 RSI: ffffffff8660550c RDI: ffff88805697e010 RBP: ffff88802a52ab38 R08: 0000000000000000 R09: ffff8880ae636cdb R10: 0000000000000000 R11: 0000000000000000 R12: ffff88805697e000 R13: 0000000000000000 R14: 1ffff92000000fa9 R15: dffffc0000000000 call_timer_fn+0x1ac/0x760 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers.part.0+0x54c/0xa20 kernel/time/timer.c:1773 __run_timers kernel/time/timer.c:1745 [inline] run_timer_softirq+0xae/0x1a0 kernel/time/timer.c:1786 __do_softirq+0x34c/0xa60 kernel/softirq.c:292 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline] do_softirq_own_stack+0x111/0x170 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:387 [inline] __irq_exit_rcu kernel/softirq.c:417 [inline] irq_exit_rcu+0x229/0x270 kernel/softirq.c:429 sysvec_apic_timer_interrupt+0x12d/0x220 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596 RIP: 0010:__mnt_want_write+0x43/0x2a0 fs/namespace.c:323 Code: 5f 89 ff 4c 8d 75 28 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 80 3c 02 00 0f 85 1b 02 00 00 48 8b 45 28 65 ff 40 04 83 44 24 fc 00 4c 8d 6d 10 48 b8 00 00 00 00 00 fc ff df 4c 89 RSP: 0018:ffffc90004997a98 EFLAGS: 00000206 RAX: 0000607f51685690 RBX: ffff8880930993a0 RCX: 1ffffffff1921234 RDX: 1ffff11012613279 RSI: ffffffff81c5c2e2 RDI: ffff8880212ab5b8 RBP: ffff8880930993a0 R08: 0000000000000000 R09: ffff8880ae636cdb R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: ffffc90004997c50 R14: ffff8880930993c8 R15: dffffc0000000000 mnt_want_write+0x42/0xb0 fs/namespace.c:355 open_last_lookups fs/namei.c:3156 [inline] path_openat+0x23df/0x2750 fs/namei.c:3357 do_filp_open+0x17e/0x3c0 fs/namei.c:3387 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179 do_sys_open fs/open.c:1195 [inline] ksys_open include/linux/syscalls.h:1388 [inline] __do_sys_open fs/open.c:1201 [inline] __se_sys_open fs/open.c:1199 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1199 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x416911 Code: Bad RIP value. RSP: 002b:00007f5d5cf21bb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 000000000050af80 RCX: 0000000000416911 RDX: 00007f5d5cf21be4 RSI: 0000000000000002 RDI: 00007f5d5cf21bd0 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000014 R10: 0000000000000009 R11: 0000000000000293 R12: 00000000ffffffff R13: 0000000000000c66 R14: 00000000004cec2a R15: 00007f5d5cf226d4