rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (10499 ticks this GP) idle=5da/1/0x4000000000000002 softirq=13058/13058 fqs=2712 (t=10500 jiffies g=6401 q=886) rcu: rcu_preempt kthread starved for 5061 jiffies! g6401 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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 0 CPU: 0 PID: 8421 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:__memcg_kmem_uncharge+0xc/0x1a0 mm/memcontrol.c:2908 Code: 48 81 c3 08 02 00 00 48 89 df 4c 89 f6 e8 8c 85 ff ff 5b 41 5e 5d c3 0f 1f 80 00 00 00 00 55 48 89 e5 41 57 41 56 41 55 41 54 <53> 50 89 f3 49 89 fc 48 b8 00 00 00 00 00 fc ff df 4c 8d 77 38 4d RSP: 0018:ffffc900021074a0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: ffffffff81489244 RBX: ffffea0002775900 RCX: ffff88809db66500 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0002775900 RBP: ffffc900021074c0 R08: 000000000003a728 R09: ffffed1014eb2701 R10: ffffed1014eb2701 R11: 0000000000000000 R12: ffff8880a284fa20 R13: dffffc0000000000 R14: 1ffff11014509f44 R15: ffff8880a75937f8 memcg_kmem_uncharge include/linux/memcontrol.h:1402 [inline] free_thread_stack+0x12e/0x590 kernel/fork.c:284 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_notrace+0xdb/0x120 kernel/sched/core.c:4309 ___preempt_schedule_notrace+0x16/0x27 arch/x86/entry/thunk_64.S:51 rcu_is_watching+0x82/0xa0 kernel/rcu/tree.c:923 rcu_read_unlock include/linux/rcupdate.h:667 [inline] memcg_kmem_get_cache+0x2e8/0x570 mm/memcontrol.c:2807 slab_pre_alloc_hook mm/slab.h:572 [inline] slab_alloc mm/slab.c:3306 [inline] kmem_cache_alloc+0x86/0x2e0 mm/slab.c:3484 proc_alloc_inode+0x1f/0xe0 fs/proc/inode.c:62 alloc_inode fs/inode.c:230 [inline] new_inode_pseudo+0x68/0x240 fs/inode.c:926 new_inode+0x28/0x1c0 fs/inode.c:955 proc_pid_make_inode+0x27/0x1d0 fs/proc/base.c:1754 proc_pid_instantiate+0x4f/0x1a0 fs/proc/base.c:3227 proc_pid_lookup+0x21f/0x300 fs/proc/base.c:3262 proc_root_lookup+0x22/0x50 fs/proc/root.c:248 __lookup_slow+0x285/0x380 fs/namei.c:1665 lookup_slow fs/namei.c:1682 [inline] walk_component+0x2d2/0x5f0 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:00007fff20a8cfc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007fff20a8cff4 RCX: 0000000000414cc0 RDX: 00007fff20a8cffa RSI: 0000000000080001 RDI: 00000000004c0a49 RBP: 00007fff20a8cff0 R08: 0000000000000000 R09: 0000000000000004 R10: 0000000000000075 R11: 0000000000000246 R12: 00000000004c0a49 R13: 00007fff20a8d510 R14: 0000000000000000 R15: 00007fff20a8d520