linux-kernel - Re: [syzbot] possible deadlock in io_poll_double

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Date:   Thu, 15 Apr 2021 09:39:28 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Hillf Danton <hdanton@...a.com>
Cc:     syzbot <syzbot+e654d4e15e6b3b9deb53@...kaller.appspotmail.com>,
        Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: [syzbot] possible deadlock in io_poll_double_wake (3)

On Thu, Apr 15, 2021 at 9:23 AM Hillf Danton <hdanton@...a.com> wrote:
>
> On Tue, 13 Apr 2021 14:07:16
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    17e7124a Merge tag '5.12-rc6-smb3' of git://git.samba.org/..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=102c3891d00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=9320464bf47598bd
> > dashboard link: https://syzkaller.appspot.com/bug?extid=e654d4e15e6b3b9deb53
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15fe3096d00000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147b9431d00000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+e654d4e15e6b3b9deb53@...kaller.appspotmail.com
> >
> > ============================================
> > WARNING: possible recursive locking detected
> > 5.12.0-rc6-syzkaller #0 Not tainted
> > --------------------------------------------
> > swapper/0/0 is trying to acquire lock:
> > ffff88802108c130 (&runtime->sleep){..-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline]
> > ffff88802108c130 (&runtime->sleep){..-.}-{2:2}, at: io_poll_double_wake+0x25f/0x6a0 fs/io_uring.c:4988
> >
> > but task is already holding lock:
> > ffff888014fd8130 (&runtime->sleep){..-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
> >
> > other info that might help us debug this:
> >  Possible unsafe locking scenario:
> >
> >        CPU0
> >        ----
> >   lock(&runtime->sleep);
> >   lock(&runtime->sleep);
> >
> >  *** DEADLOCK ***
>
> Wasnt it fixed by 1c3b3e6527e57, given the same call trace at the first
> glance?

1c3b3e6527e57 is present in the tested tree on 17e7124a. So syzbot
just gave the answer to your question.

> >  May be due to missing lock nesting notation
> >
> > 2 locks held by swapper/0/0:
> >  #0: ffff888020d18108 (&group->lock){..-.}-{2:2}, at: _snd_pcm_stream_lock_irqsave+0x9f/0xd0 sound/core/pcm_native.c:170
> >  #1: ffff888014fd8130 (&runtime->sleep){..-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137
> >
> > stack backtrace:
> > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc6-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> >  <IRQ>
> >  __dump_stack lib/dump_stack.c:79 [inline]
> >  dump_stack+0x141/0x1d7 lib/dump_stack.c:120
> >  print_deadlock_bug kernel/locking/lockdep.c:2829 [inline]
> >  check_deadlock kernel/locking/lockdep.c:2872 [inline]
> >  validate_chain kernel/locking/lockdep.c:3661 [inline]
> >  __lock_acquire.cold+0x14c/0x3b4 kernel/locking/lockdep.c:4900
> >  lock_acquire kernel/locking/lockdep.c:5510 [inline]
> >  lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475
> >  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
> >  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
> >  spin_lock include/linux/spinlock.h:354 [inline]
> >  io_poll_double_wake+0x25f/0x6a0 fs/io_uring.c:4988
> >  __wake_up_common+0x147/0x650 kernel/sched/wait.c:108
> >  __wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:138
> >  snd_pcm_update_state+0x46a/0x540 sound/core/pcm_lib.c:203
> >  snd_pcm_update_hw_ptr0+0xa75/0x1a50 sound/core/pcm_lib.c:464
> >  snd_pcm_period_elapsed+0x160/0x250 sound/core/pcm_lib.c:1805
> >  dummy_hrtimer_callback+0x94/0x1b0 sound/drivers/dummy.c:377
> >  __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
> >  __hrtimer_run_queues+0x609/0xe40 kernel/time/hrtimer.c:1601
> >  hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1618
> >  __do_softirq+0x29b/0x9f6 kernel/softirq.c:345
> >  invoke_softirq kernel/softirq.c:221 [inline]
> >  __irq_exit_rcu kernel/softirq.c:422 [inline]
> >  irq_exit_rcu+0x134/0x200 kernel/softirq.c:434
> >  sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
> >  </IRQ>
> >  asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
> > RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
> > RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
> > RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:137 [inline]
> > RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
> > RIP: 0010:acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:517
> > Code: cd cb 6e f8 84 db 75 ac e8 14 c5 6e f8 e8 1f b4 74 f8 e9 0c 00 00 00 e8 05 c5 6e f8 0f 00 2d 0e 18 c8 00 e8 f9 c4 6e f8 fb f4 <9c> 5b 81 e3 00 02 00 00 fa 31 ff 48 89 de e8 04 cd 6e f8 48 85 db
> > RSP: 0018:ffffffff8bc07d60 EFLAGS: 00000293
> > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > RDX: ffffffff8bcbc400 RSI: ffffffff89052c17 RDI: 0000000000000000
> > RBP: ffff888015078064 R08: 0000000000000001 R09: 0000000000000001
> > R10: ffffffff8179e058 R11: 0000000000000000 R12: 0000000000000001
> > R13: ffff888015078000 R14: ffff888015078064 R15: ffff888143a48004
> >  acpi_idle_enter+0x361/0x500 drivers/acpi/processor_idle.c:654
> >  cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237
> >  cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351
> >  call_cpuidle kernel/sched/idle.c:158 [inline]
> >  cpuidle_idle_call kernel/sched/idle.c:239 [inline]
> >  do_idle+0x3e1/0x590 kernel/sched/idle.c:300
> >
> >
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@...glegroups.com.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > syzbot can test patches for this issue, for details see:
> > https://goo.gl/tpsmEJ#testing-patches