rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): (detected by 0, t=10502 jiffies, g=239729, q=56) rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4295102576-4295092076), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies! g239729 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=90569 rcu: rcu_preempt kthread starved for 10500 jiffies! g239729 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:26384 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4681 [inline] __schedule+0xc07/0x11f0 kernel/sched/core.c:5938 schedule+0x14b/0x210 kernel/sched/core.c:6017 schedule_timeout+0x1aa/0x2f0 kernel/time/timer.c:1881 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline] rcu_gp_kthread+0x10fd/0x1720 kernel/rcu/tree.c:2169 kthread+0x453/0x480 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 8421 Comm: syz-fuzzer Not tainted 5.14.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rcu_read_lock_sched_held+0x1/0x110 kernel/rcu/update.c:120 Code: 00 00 00 00 00 0f 1f 40 00 e9 ab 63 1f 00 66 66 2e 0f 1f 84 00 00 00 00 00 e9 9b 66 1f 00 66 66 2e 0f 1f 84 00 00 00 00 00 55 <48> 89 e5 41 57 41 56 53 48 83 e4 e0 48 83 ec 60 65 48 8b 04 25 28 RSP: 0018:ffffc90000dc0ac8 EFLAGS: 00000086 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff816212eb RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8dba6fa8 RBP: ffffc90000dc0c68 R08: dffffc0000000000 R09: fffffbfff1b74df6 R10: fffffbfff1b74df6 R11: 0000000000000000 R12: dffffc0000000000 R13: 1ffff920001b816c R14: 0000000000000001 R15: 0000000000000000 FS: 000000c00002e090(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000014a53ad CR3: 0000000018066000 CR4: 00000000001526e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_lock_acquire+0x59/0x190 include/trace/events/lock.h:13 lock_acquire+0xa4/0x4a0 kernel/locking/lockdep.c:5596 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0xae/0xf0 kernel/locking/spinlock.c:167 __run_hrtimer kernel/time/hrtimer.c:1541 [inline] __hrtimer_run_queues+0x546/0xa60 kernel/time/hrtimer.c:1601 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1663 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1106 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1100 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:finish_lock_switch+0xf0/0x1c0 kernel/sched/core.c:4436 Code: 61 0c 00 74 11 48 89 df be ff ff ff ff e8 08 23 80 08 85 c0 74 27 4d 85 ff 75 44 4c 89 f7 e8 87 cd 82 08 e8 f2 40 2d 00 fb 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 4d 85 ff 75 92 eb a8 0f 0b 4d RSP: 0018:ffffc90001b3fa30 EFLAGS: 00000282 RAX: aef41c9584be4400 RBX: ffff88802902b8b4 RCX: ffffffff9070b703 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 1ffff110173aa400 R08: ffffffff8186a530 R09: ffffed10173aa2a9 R10: ffffed10173aa2a9 R11: 0000000000000000 R12: ffff8880b9d52000 R13: dffffc0000000000 R14: ffff8880b9d51540 R15: 0000000000000000 finish_task_switch+0x140/0x630 kernel/sched/core.c:4553 context_switch kernel/sched/core.c:4684 [inline] __schedule+0xc0f/0x11f0 kernel/sched/core.c:5938 schedule+0x14b/0x210 kernel/sched/core.c:6017 freezable_schedule include/linux/freezer.h:172 [inline] do_nanosleep+0x1b6/0x7b0 kernel/time/hrtimer.c:1896 hrtimer_nanosleep+0x239/0x470 kernel/time/hrtimer.c:1949 __do_sys_nanosleep kernel/time/hrtimer.c:1983 [inline] __se_sys_nanosleep kernel/time/hrtimer.c:1970 [inline] __x64_sys_nanosleep+0x228/0x290 kernel/time/hrtimer.c:1970 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x46dabd Code: 8b 44 24 20 b9 40 42 0f 00 f7 f1 48 89 04 24 b8 e8 03 00 00 f7 e2 48 89 44 24 08 48 89 e7 be 00 00 00 00 b8 23 00 00 00 0f 05 <48> 8b 6c 24 10 48 83 c4 18 c3 cc cc cc cc cc cc cc cc cc cc cc cc RSP: 002b:000000c00003df18 EFLAGS: 00000202 ORIG_RAX: 0000000000000023 RAX: ffffffffffffffda RBX: 0000000000000014 RCX: 000000000046dabd RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000c00003df18 RBP: 000000c00003df28 R08: 00007fff85de6080 R09: 0000000000000010 R10: 00007fff85de60b8 R11: 0000000000000202 R12: 000000000043b6a0 R13: 0000000000000000 R14: 000000000094d6d0 R15: 0000000000000000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 00 00 add %al,(%rax) 2: 00 00 add %al,(%rax) 4: 0f 1f 40 00 nopl 0x0(%rax) 8: e9 ab 63 1f 00 jmpq 0x1f63b8 d: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 14: 00 00 00 00 18: e9 9b 66 1f 00 jmpq 0x1f66b8 1d: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 24: 00 00 00 00 28: 55 push %rbp * 29: 48 89 e5 mov %rsp,%rbp <-- trapping instruction 2c: 41 57 push %r15 2e: 41 56 push %r14 30: 53 push %rbx 31: 48 83 e4 e0 and $0xffffffffffffffe0,%rsp 35: 48 83 ec 60 sub $0x60,%rsp 39: 65 gs 3a: 48 rex.W 3b: 8b .byte 0x8b 3c: 04 25 add $0x25,%al 3e: 28 .byte 0x28