rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10499 ticks this GP) idle=205/1/0x4000000000000000 softirq=128650/128651 fqs=2 (t=10500 jiffies g=222953 q=37) rcu: rcu_preempt kthread timer wakeup didn't happen for 10495 jiffies! g222953 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=89821 rcu: rcu_preempt kthread starved for 10496 jiffies! g222953 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26544 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb72/0x1460 kernel/sched/core.c:6287 schedule+0x14b/0x210 kernel/sched/core.c:6366 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1957 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2130 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 28453 Comm: syz-executor.2 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:queued_write_lock_slowpath+0x1a3/0x470 kernel/locking/qrwlock.c:78 Code: c0 74 24 44 89 f9 80 e1 07 80 c1 03 38 c1 7c 17 4c 89 ff e8 6f ec 67 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 8b 07 <3d> 00 01 00 00 75 c6 43 8a 04 34 84 c0 75 5d c7 44 24 50 00 01 00 RSP: 0018:ffffc900043bf820 EFLAGS: 00000046 RAX: 0000000000000300 RBX: ffffc900043bf870 RCX: ffffffff816717b7 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8c60a040 RBP: ffffc900043bf8d0 R08: dffffc0000000000 R09: fffffbfff18c1409 R10: fffffbfff18c1409 R11: 0000000000000000 R12: 1ffff92000877f0e R13: 1ffffffff18c1408 R14: dffffc0000000000 R15: ffffffff8c60a040 FS: 0000555556316400(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555556317808 CR3: 000000014fa68000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: queued_write_lock include/asm-generic/qrwlock.h:97 [inline] do_raw_write_lock+0x38a/0x4e0 kernel/locking/spinlock_debug.c:210 __raw_write_lock_irq include/linux/rwlock_api_smp.h:197 [inline] _raw_write_lock_irq+0xdb/0x110 kernel/locking/spinlock.c:316 copy_process+0x34b4/0x5c90 kernel/fork.c:2313 kernel_clone+0x230/0x7d0 kernel/fork.c:2584 __do_sys_clone kernel/fork.c:2701 [inline] __se_sys_clone kernel/fork.c:2685 [inline] __x64_sys_clone+0x245/0x2b0 kernel/fork.c:2685 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2233928e61 Code: 48 85 ff 74 3d 48 85 f6 74 38 48 83 ee 10 48 89 4e 08 48 89 3e 48 89 d7 4c 89 c2 4d 89 c8 4c 8b 54 24 08 b8 38 00 00 00 0f 05 <48> 85 c0 7c 13 74 01 c3 31 ed 58 5f ff d0 48 89 c7 b8 3c 00 00 00 RSP: 002b:00007fff25f3ce48 EFLAGS: 00000206 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007f2230e9d700 RCX: 00007f2233928e61 RDX: 00007f2230e9d9d0 RSI: 00007f2230e9d2f0 RDI: 00000000003d0f00 RBP: 00007fff25f3d080 R08: 00007f2230e9d700 R09: 00007f2230e9d700 R10: 00007f2230e9d9d0 R11: 0000000000000206 R12: 00007fff25f3cefe R13: 00007fff25f3ceff R14: 00007f2230e9d300 R15: 0000000000022000 NMI backtrace for cpu 1 CPU: 1 PID: 28441 Comm: syz-executor.5 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+0x1dc/0x2d8 lib/dump_stack.c:106 nmi_cpu_backtrace+0x45f/0x490 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x16a/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x22d/0x390 kernel/rcu/tree_stall.h:343 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq+0x1e33/0x2bc0 kernel/rcu/tree.c:2599 update_process_times+0x197/0x200 kernel/time/timer.c:1785 tick_sched_handle kernel/time/tick-sched.c:226 [inline] tick_sched_timer+0x27d/0x420 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x3e/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194 Code: 9c 8f 44 24 20 42 80 3c 23 00 74 08 4c 89 f7 e8 a2 f1 d1 f7 f6 44 24 21 02 75 4e 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 97 51 5c f7 65 8b 05 c8 dc 04 76 85 c0 74 3f 48 c7 04 24 0e 36 RSP: 0018:ffffc90000dc09e0 EFLAGS: 00000206 RAX: 3019d0c4ad3abb00 RBX: 1ffff920001b8140 RCX: ffffffff8165a2f1 RDX: dffffc0000000000 RSI: 0000000000000104 RDI: 0000000000000001 RBP: ffffc90000dc0a70 R08: dffffc0000000000 R09: fffffbfff1fa37f4 R10: fffffbfff1fa37f4 R11: 0000000000000000 R12: dffffc0000000000 R13: 1ffff920001b813c R14: ffffc90000dc0a00 R15: 0000000000000246 __mod_timer+0x98d/0xd20 kernel/time/timer.c:1065 call_timer_fn+0xf6/0x210 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers+0x71a/0x910 kernel/time/timer.c:1734 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1747 __do_softirq+0x392/0x7a3 kernel/softirq.c:558 __irq_exit_rcu+0xec/0x170 kernel/softirq.c:636 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:lock_is_held_type+0x141/0x190 Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f RSP: 0018:ffffc9000442f978 EFLAGS: 00000206 RAX: 3019d0c4ad3abb00 RBX: 0000000000000000 RCX: 0000000000000003 RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000 RBP: 0000000000000003 R08: dffffc0000000000 R09: ffffed10173a64a2 R10: ffffed10173a64a2 R11: 0000000000000000 R12: 0000000000000246 R13: ffff888088b65580 R14: 00000000ffffffff R15: ffffffff8c91c8e0 lock_is_held include/linux/lockdep.h:283 [inline] rcu_read_lock_sched_held+0x89/0x130 kernel/rcu/update.c:125 trace_lock_acquire+0x59/0x190 include/trace/events/lock.h:13 lock_acquire+0xa5/0x4d0 kernel/locking/lockdep.c:5596 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:363 [inline] task_lock include/linux/sched/task.h:168 [inline] chroot_fs_refs+0xbf/0x5c0 fs/fs_struct.c:66 __do_sys_pivot_root fs/namespace.c:3899 [inline] __se_sys_pivot_root+0x1f70/0x20e0 fs/namespace.c:3816 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f087ca32a39 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:00007f0879f66188 EFLAGS: 00000246 ORIG_RAX: 000000000000009b RAX: ffffffffffffffda RBX: 00007f087cb360e0 RCX: 00007f087ca32a39 RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 00000000200000c0 RBP: 00007f087ca8ce8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd35703f0f R14: 00007f0879f66300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: c0 74 24 44 89 shlb $0x89,0x44(%rsp) 5: f9 stc 6: 80 e1 07 and $0x7,%cl 9: 80 c1 03 add $0x3,%cl c: 38 c1 cmp %al,%cl e: 7c 17 jl 0x27 10: 4c 89 ff mov %r15,%rdi 13: e8 6f ec 67 00 callq 0x67ec87 18: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 1f: 00 00 00 22: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 27: 41 8b 07 mov (%r15),%eax * 2a: 3d 00 01 00 00 cmp $0x100,%eax <-- trapping instruction 2f: 75 c6 jne 0xfffffff7 31: 43 8a 04 34 mov (%r12,%r14,1),%al 35: 84 c0 test %al,%al 37: 75 5d jne 0x96 39: c7 .byte 0xc7 3a: 44 24 50 rex.R and $0x50,%al 3d: 00 01 add %al,(%rcx)