rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P1186/1:b..l P32726/1:b..l (detected by 0, t=10502 jiffies, g=144373, q=1073) task:syz-executor.5 state:R running task stack:28960 pid:32726 ppid: 30209 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_notrace+0x5b/0xd0 kernel/sched/core.c:6538 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:36 rcu_read_unlock_sched_notrace include/linux/rcupdate.h:809 [inline] trace_lock_acquire include/trace/events/lock.h:13 [inline] lock_acquire+0x458/0x510 kernel/locking/lockdep.c:5596 rcu_lock_acquire include/linux/rcupdate.h:267 [inline] rcu_read_lock include/linux/rcupdate.h:687 [inline] ext4_get_group_desc+0x146/0x500 fs/ext4/balloc.c:284 recently_deleted fs/ext4/ialloc.c:685 [inline] find_inode_bit+0x1c4/0x580 fs/ext4/ialloc.c:731 __ext4_new_inode+0xc64/0x5ba0 fs/ext4/ialloc.c:1066 ext4_symlink+0x489/0xd50 fs/ext4/namei.c:3293 vfs_symlink fs/namei.c:4250 [inline] vfs_symlink+0x479/0x730 fs/namei.c:4235 do_symlinkat+0x261/0x2e0 fs/namei.c:4279 __do_sys_symlink fs/namei.c:4301 [inline] __se_sys_symlink fs/namei.c:4299 [inline] __x64_sys_symlink+0x75/0x90 fs/namei.c:4299 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: 0033:0x7fcdae76c347 RSP: 002b:00007ffdc14959e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcdae76c347 RDX: 00007ffdc1495ac3 RSI: 00007fcdae7c6d09 RDI: 00007ffdc1495ab0 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffdc1495880 R10: 00007ffdc1495737 R11: 0000000000000206 R12: 0000000000000001 R13: 0000000000000001 R14: 0000000000000001 R15: 00007ffdc1495ab0 task:kworker/u4:5 state:R running task stack:23864 pid: 1186 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6687 irqentry_exit+0x31/0x80 kernel/entry/common.c:425 asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:646 RIP: 0010:check_kcov_mode+0x31/0x40 kernel/kcov.c:175 Code: 89 c2 81 e2 00 01 00 00 a9 00 01 ff 00 74 10 31 c0 85 d2 74 15 8b 96 64 15 00 00 85 d2 74 0b 8b 86 40 15 00 00 39 f8 0f 94 c0 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 31 c0 65 8b 15 67 e9 RSP: 0018:ffffc90004c3fc78 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88801dc26300 RDX: 0000000000000000 RSI: ffff88801dc26300 RDI: 0000000000000003 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff88d39a81 R11: 0000000000000000 R12: ffffc90004c3fdb0 R13: 0000000000000000 R14: dffffc0000000000 R15: 000000000000013f write_comp_data kernel/kcov.c:218 [inline] __sanitizer_cov_trace_const_cmp1+0x22/0x80 kernel/kcov.c:270 rcu_read_unlock include/linux/rcupdate.h:716 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:414 [inline] batadv_nc_worker+0x841/0xfa0 net/batman-adv/network-coding.c:721 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: rcu_preempt kthread starved for 10500 jiffies! g144373 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 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:28832 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 0 CPU: 0 PID: 32720 Comm: syz-executor.1 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:vmx_do_interrupt_nmi_irqoff+0x10/0x20 arch/x86/kvm/vmx/vmenter.S:327 Code: 41 5b 41 5a 41 59 41 58 5e 5f 5a 59 58 5d c3 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 48 83 e4 f0 6a 18 55 9c 6a 10 ff d7 <48> 89 ec 5d c3 cc cc cc cc cc cc cc cc cc cc cc 41 57 48 8d 47 08 RSP: 0018:ffffc90002f87b48 EFLAGS: 00000082 RAX: 0000000000000000 RBX: ffff888083095200 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff89400bf0 RBP: ffffc90002f87b48 R08: 0000000080000000 R09: ffff888083095467 R10: ffffffff811e9aec R11: 0000000000000000 R12: 0000000000000bf0 R13: 0000000089400000 R14: 0000000000000000 R15: ffff888083095230 handle_interrupt_nmi_irqoff arch/x86/kvm/vmx/vmx.c:6352 [inline] handle_external_interrupt_irqoff arch/x86/kvm/vmx/vmx.c:6382 [inline] vmx_handle_exit_irqoff arch/x86/kvm/vmx/vmx.c:6393 [inline] vmx_handle_exit_irqoff+0x4d2/0x750 arch/x86/kvm/vmx/vmx.c:6385 vcpu_enter_guest+0x2698/0x4410 arch/x86/kvm/x86.c:9684 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: 0033:0x7f1f3f8d8a39 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:00007f1f3ce4e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f1f3f9dbf60 RCX: 00007f1f3f8d8a39 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 RBP: 00007f1f3f932c5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd9cb5f20f R14: 00007f1f3ce4e300 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 89 c2 mov %eax,%edx 2: 81 e2 00 01 00 00 and $0x100,%edx 8: a9 00 01 ff 00 test $0xff0100,%eax d: 74 10 je 0x1f f: 31 c0 xor %eax,%eax 11: 85 d2 test %edx,%edx 13: 74 15 je 0x2a 15: 8b 96 64 15 00 00 mov 0x1564(%rsi),%edx 1b: 85 d2 test %edx,%edx 1d: 74 0b je 0x2a 1f: 8b 86 40 15 00 00 mov 0x1540(%rsi),%eax 25: 39 f8 cmp %edi,%eax 27: 0f 94 c0 sete %al * 2a: c3 retq <-- trapping instruction 2b: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 32: 00 00 00 00 36: 0f 1f 00 nopl (%rax) 39: 31 c0 xor %eax,%eax 3b: 65 gs 3c: 8b .byte 0x8b 3d: 15 .byte 0x15 3e: 67 addr32 3f: e9 .byte 0xe9