rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6589/1:b..l (detected by 1, t=10502 jiffies, g=462717, q=13555) task:syz-executor.2 state:R running task stack:23728 pid: 6589 ppid: 1 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4983 [inline] __schedule+0xab2/0x4d90 kernel/sched/core.c:6293 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6459 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 __raw_read_unlock include/linux/rwlock_api_smp.h:233 [inline] _raw_read_unlock+0x36/0x40 kernel/locking/spinlock.c:260 zap_pid_ns_processes+0x271/0x660 kernel/pid_namespace.c:207 find_child_reaper kernel/exit.c:548 [inline] forget_original_parent kernel/exit.c:637 [inline] exit_notify kernel/exit.c:674 [inline] do_exit+0x243d/0x2b40 kernel/exit.c:852 do_group_exit+0x125/0x310 kernel/exit.c:929 __do_sys_exit_group kernel/exit.c:940 [inline] __se_sys_exit_group kernel/exit.c:938 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:938 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f4a4c106ae9 RSP: 002b:00007fffa7b98138 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f4a4c106ae9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000043 RBP: 0000000000000000 R08: 000000000000002e R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4a4c160fd3 R13: 000000000000000b R14: 0000000000000001 R15: 00007fffa7b98320 rcu: rcu_preempt kthread timer wakeup didn't happen for 1217 jiffies! g462717 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=170238 rcu: rcu_preempt kthread starved for 1218 jiffies! g462717 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:27984 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4983 [inline] __schedule+0xab2/0x4d90 kernel/sched/core.c:6293 schedule+0xd2/0x260 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1963 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2136 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 26503 Comm: syz-executor.2 Not tainted 5.16.0-rc2-next-20211124-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:458 print_other_cpu_stall kernel/rcu/tree_stall.h:563 [inline] check_cpu_stall kernel/rcu/tree_stall.h:706 [inline] rcu_pending kernel/rcu/tree.c:3919 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2617 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5605 Code: a7 a5 7e 83 f8 01 0f 85 b4 02 00 00 9c 58 f6 c4 02 0f 85 9f 02 00 00 48 83 7c 24 08 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24 RSP: 0018:ffffc900215775d0 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: 1ffff920042aeebc RCX: 17ed837246550812 RDX: 1ffff1102f87fc44 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ff7ba07 R10: fffffbfff1fef740 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: ffffffff8bb843e0 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:268 [inline] rcu_read_lock include/linux/rcupdate.h:694 [inline] folio_memcg_lock+0x3a/0x3e0 mm/memcontrol.c:2034 page_remove_rmap+0x25/0x1480 mm/rmap.c:1348 zap_pte_range mm/memory.c:1357 [inline] zap_pmd_range mm/memory.c:1467 [inline] zap_pud_range mm/memory.c:1496 [inline] zap_p4d_range mm/memory.c:1517 [inline] unmap_page_range+0xf0e/0x29f0 mm/memory.c:1538 unmap_single_vma+0x198/0x310 mm/memory.c:1583 unmap_vmas+0x16b/0x2f0 mm/memory.c:1615 exit_mmap+0x1d0/0x630 mm/mmap.c:3176 __mmput+0x122/0x4b0 kernel/fork.c:1115 mmput+0x56/0x60 kernel/fork.c:1136 exit_mm kernel/exit.c:507 [inline] do_exit+0xb27/0x2b40 kernel/exit.c:819 do_group_exit+0x125/0x310 kernel/exit.c:929 get_signal+0x34c/0x28b0 kernel/signal.c:2859 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f4a4c106ae9 Code: Unable to access opcode bytes at RIP 0x7f4a4c106abf. RSP: 002b:00007f4a4965b218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f4a4c21a028 RCX: 00007f4a4c106ae9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f4a4c21a028 RBP: 00007f4a4c21a020 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4a4c21a02c R13: 00007fffa7b9800f R14: 00007f4a4965b300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: a7 cmpsl %es:(%rdi),%ds:(%rsi) 1: a5 movsl %ds:(%rsi),%es:(%rdi) 2: 7e 83 jle 0xffffff87 4: f8 clc 5: 01 0f add %ecx,(%rdi) 7: 85 b4 02 00 00 9c 58 test %esi,0x589c0000(%rdx,%rax,1) e: f6 c4 02 test $0x2,%ah 11: 0f 85 9f 02 00 00 jne 0x2b6 17: 48 83 7c 24 08 00 cmpq $0x0,0x8(%rsp) 1d: 74 01 je 0x20 1f: fb sti 20: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 27: fc ff df * 2a: 48 01 c3 add %rax,%rbx <-- trapping instruction 2d: 48 c7 03 00 00 00 00 movq $0x0,(%rbx) 34: 48 c7 43 08 00 00 00 movq $0x0,0x8(%rbx) 3b: 00 3c: 48 rex.W 3d: 8b .byte 0x8b 3e: 84 .byte 0x84 3f: 24 .byte 0x24