rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2971/1:b..l (detected by 1, t=10502 jiffies, g=81641, q=79) task:systemd-udevd state:R running task stack:22920 pid: 2971 ppid: 1 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6459 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:403 [inline] fast_dput fs/dcache.c:767 [inline] fast_dput fs/dcache.c:740 [inline] dput+0x503/0xbc0 fs/dcache.c:875 path_put+0x2d/0x60 fs/namei.c:557 vfs_statx+0x244/0x390 fs/stat.c:231 vfs_fstatat fs/stat.c:243 [inline] vfs_lstat include/linux/fs.h:3356 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:398 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: 0033:0x7ffaa9605335 RSP: 002b:00007ffe287b4b48 EFLAGS: 00000246 ORIG_RAX: 0000000000000006 RAX: ffffffffffffffda RBX: 00005567a35278e0 RCX: 00007ffaa9605335 RDX: 00007ffe287b4b80 RSI: 00007ffe287b4b80 RDI: 00005567a35268e0 RBP: 00007ffe287b4c40 R08: 00007ffaa98c4268 R09: 0000000000001010 R10: 0000000000000020 R11: 0000000000000246 R12: 00005567a35268e0 R13: 00005567a3526906 R14: 00005567a35126e1 R15: 00005567a35126e6 rcu: rcu_preempt kthread starved for 10502 jiffies! g81641 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: task:rcu_preempt state:R running task stack:28952 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 schedule+0xd3/0x270 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130 kthread+0x3e5/0x4d0 kernel/kthread.c:319 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: 19991 Comm: syz-executor.4 Not tainted 5.15.0-rc6-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:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 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:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2599 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:1421 __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:vcpu_enter_guest+0x26ba/0x4410 arch/x86/kvm/x86.c:9695 Code: 4c 89 e7 e8 e8 51 0d 00 48 c7 c7 40 52 82 89 e8 cc 1a 25 08 65 4c 89 25 bc 99 f0 7e e8 6f f1 6a 00 fb 49 8d bc 24 e0 20 00 00 <48> b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f RSP: 0018:ffffc90004b4fb90 EFLAGS: 00000202 RAX: 00000000006aef6d RBX: 1ffff92000969f7c RCX: 1ffffffff1fadf1a RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88803428a8e0 RBP: ffffc90004b4fcb0 R08: 0000000000000001 R09: ffffffff8fd05aff R10: 0000000000000001 R11: 0000000000000000 R12: ffff888034288800 R13: ffff888034288838 R14: 0000000000000000 R15: ffff888034288830 vcpu_run arch/x86/kvm/x86.c:9802 [inline] kvm_arch_vcpu_ioctl_run+0x47c/0x1b10 arch/x86/kvm/x86.c:10034 kvm_vcpu_ioctl+0x570/0xf30 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3779 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 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: 0033:0x7fa8a16b2a39 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa89ec28188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fa8a17b5f60 RCX: 00007fa8a16b2a39 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 RBP: 00007fa8a170cc5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff29f0590f R14: 00007fa89ec28300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 4c 89 e7 mov %r12,%rdi 3: e8 e8 51 0d 00 callq 0xd51f0 8: 48 c7 c7 40 52 82 89 mov $0xffffffff89825240,%rdi f: e8 cc 1a 25 08 callq 0x8251ae0 14: 65 4c 89 25 bc 99 f0 mov %r12,%gs:0x7ef099bc(%rip) # 0x7ef099d8 1b: 7e 1c: e8 6f f1 6a 00 callq 0x6af190 21: fb sti 22: 49 8d bc 24 e0 20 00 lea 0x20e0(%r12),%rdi 29: 00 * 2a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax <-- trapping instruction 31: fc ff df 34: 48 89 fa mov %rdi,%rdx 37: 48 c1 ea 03 shr $0x3,%rdx 3b: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) 3f: 0f .byte 0xf