Re: [syzbot] [ext4?] possible deadlock in console_flush_all (2)

[Peter Zijlstra]

On Tue, Oct 17, 2023 at 06:07:50AM -0700, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    213f891525c2 Merge tag 'probes-fixes-v6.6-rc6' of git://gi..

> list_add corruption. next->prev should be prev (ffff8880b993d228), but was caff904900000000. (next=ffff8880783659f8).

Urgh, I've not seen that happen before. How reliable does this trigger?

>  __list_add_valid_or_report+0xa2/0x100 lib/list_debug.c:29
>  __list_add_valid include/linux/list.h:88 [inline]
>  __list_add include/linux/list.h:150 [inline]
>  list_add include/linux/list.h:169 [inline]
>  account_entity_enqueue kernel/sched/fair.c:3534 [inline]
>  enqueue_entity+0x97b/0x1490 kernel/sched/fair.c:5117
>  enqueue_task_fair+0x15b/0xbc0 kernel/sched/fair.c:6536
>  enqueue_task kernel/sched/core.c:2102 [inline]
>  activate_task kernel/sched/core.c:2132 [inline]
>  ttwu_do_activate+0x214/0xd90 kernel/sched/core.c:3787
>  ttwu_queue kernel/sched/core.c:4029 [inline]
>  try_to_wake_up+0x8e7/0x15b0 kernel/sched/core.c:4346
>  autoremove_wake_function+0x16/0x150 kernel/sched/wait.c:424
>  __wake_up_common+0x140/0x5a0 kernel/sched/wait.c:107
>  __wake_up_common_lock+0xd6/0x140 kernel/sched/wait.c:138
>  wake_up_klogd_work_func kernel/printk/printk.c:3840 [inline]
>  wake_up_klogd_work_func+0x90/0xa0 kernel/printk/printk.c:3829
>  irq_work_single+0x1b5/0x260 kernel/irq_work.c:221
>  irq_work_run_list kernel/irq_work.c:252 [inline]
>  irq_work_run_list+0x92/0xc0 kernel/irq_work.c:235
>  update_process_times+0x1d5/0x220 kernel/time/timer.c:2074
>  tick_sched_handle+0x8e/0x170 kernel/time/tick-sched.c:254
>  tick_sched_timer+0xe9/0x110 kernel/time/tick-sched.c:1492
>  __run_hrtimer kernel/time/hrtimer.c:1688 [inline]
>  __hrtimer_run_queues+0x647/0xc10 kernel/time/hrtimer.c:1752
>  hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814
>  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1063 [inline]
>  __sysvec_apic_timer_interrupt+0x105/0x3f0 arch/x86/kernel/apic/apic.c:1080
>  sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1074
>  </IRQ>