Dear Linux folks,


Running rcutorture on the POWER8 system IBM S822LC with Ubuntu 20.10, it 
found the bug below. I more or less used rcu/dev (0ba8896d2fd7 
(lib/irq_poll: Declare IRQ_POLL softirq vector as ksoftirqd-parking 
safe)) [1]. The bug manifested for the four configurations below.

1.  results-rcutorture-kasan/SRCU-T
2.  results-rcutorture-kasan/TINY02
3.  results-rcutorture/SRCU-T
4.  results-rcutorture/TINY02

For example, the attached

 
/dev/shm/linux/tools/testing/selftests/rcutorture/res/2022.02.11-22.00.51-torture/results-rcutorture-kasan/SRCU-T/console.log

contains:

```
[    0.012154][    T1] BUG: sleeping function called from invalid 
context at include/linux/sched/mm.h:256
[    0.013128][    T1] in_atomic(): 0, irqs_disabled(): 1, non_block: 0, 
pid: 1, name: swapper/0
[    0.014015][    T1] preempt_count: 0, expected: 0
[    0.014505][    T1] 2 locks held by swapper/0/1:
[    0.014987][    T1]  #0: c0000000026108a0 
(cpu_hotplug_lock){.+.+}-{0:0}, at: static_key_enable+0x24/0x50
[    0.015995][    T1]  #1: c0000000027416c8 
(jump_label_mutex){+.+.}-{3:3}, at: static_key_enable_cpuslocked+0x88/0x120
[    0.017107][    T1] irq event stamp: 46
[    0.017507][    T1] hardirqs last  enabled at (45): 
[<c0000000010c1054>] _raw_spin_unlock_irqrestore+0x94/0xd0
[    0.018549][    T1] hardirqs last disabled at (46): 
[<c0000000000a9bc4>] do_patch_instruction+0x3b4/0x4a0
[    0.019549][    T1] softirqs last  enabled at (0): 
[<c000000000149540>] copy_process+0x8d0/0x1df0
[    0.020474][    T1] softirqs last disabled at (0): 
[<0000000000000000>] 0x0
[    0.021200][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 
5.17.0-rc3-00349-gd3a9fd9fed88 #34
[    0.022115][    T1] Call Trace:
[    0.022443][    T1] [c0000000084837d0] [c000000000961aac] 
dump_stack_lvl+0xa0/0xec (unreliable)
[    0.023356][    T1] [c000000008483820] [c00000000019b314] 
__might_resched+0x2f4/0x310
[    0.024174][    T1] [c0000000084838b0] [c0000000004c0c70] 
kmem_cache_alloc+0x220/0x4b0
[    0.025000][    T1] [c000000008483920] [c000000000448af4] 
__pud_alloc+0x74/0x1d0
[    0.025772][    T1] [c000000008483970] [c00000000008fe3c] 
hash__map_kernel_page+0x2cc/0x390
[    0.026643][    T1] [c000000008483a20] [c0000000000a9944] 
do_patch_instruction+0x134/0x4a0
[    0.027511][    T1] [c000000008483a70] [c0000000000559d4] 
arch_jump_label_transform+0x64/0x78
[    0.028401][    T1] [c000000008483a90] [c0000000003d6288] 
__jump_label_update+0x148/0x180
[    0.029254][    T1] [c000000008483b30] [c0000000003d6800] 
static_key_enable_cpuslocked+0xd0/0x120
[    0.030179][    T1] [c000000008483ba0] [c0000000003d6880] 
static_key_enable+0x30/0x50
[    0.030996][    T1] [c000000008483bd0] [c00000000200a8f4] 
check_kvm_guest+0x60/0x88
[    0.031799][    T1] [c000000008483c00] [c000000002027744] 
pSeries_smp_probe+0x54/0xb0
[    0.032617][    T1] [c000000008483c30] [c000000002011db8] 
smp_prepare_cpus+0x3e0/0x430
[    0.033444][    T1] [c000000008483cd0] [c000000002004908] 
kernel_init_freeable+0x20c/0x43c
[    0.034307][    T1] [c000000008483db0] [c000000000012c00] 
kernel_init+0x30/0x1a0
[    0.035078][    T1] [c000000008483e10] [c00000000000cd64] 
ret_from_kernel_thread+0x5c/0x64
```


Kind regards,

Paul


[1]: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git