________________________________________ 发件人: Jens Axboe <axboe@xxxxxxxxx> 发送时间: 2021年3月1日 7:08 收件人: syzbot; asml.silence@xxxxxxxxx; io-uring@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; syzkaller-bugs@xxxxxxxxxxxxxxxx; viro@xxxxxxxxxxxxxxxxxx 主题: Re: possible deadlock in io_poll_double_wake (2) [Please note: This e-mail is from an EXTERNAL e-mail address] On 2/27/21 5:42 PM, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 5695e516 Merge tag 'io_uring-worker.v3-2021-02-25' of git:.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=114e3866d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=8c76dad0946df1f3 > dashboard link: https://syzkaller.appspot.com/bug?extid=28abd693db9e92c160d8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122ed9b6d00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14d5a292d00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+28abd693db9e92c160d8@xxxxxxxxxxxxxxxxxxxxxxxxx > > ============================================ > WARNING: possible recursive locking detected > 5.11.0-syzkaller #0 Not tainted > -------------------------------------------- > swapper/1/0 is trying to acquire lock: > ffff88801b2b1130 (&runtime->sleep){..-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] > ffff88801b2b1130 (&runtime->sleep){..-.}-{2:2}, at: io_poll_double_wake+0x25f/0x6a0 fs/io_uring.c:4960 > > but task is already holding lock: > ffff88801b2b3130 (&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 *** > > May be due to missing lock nesting notation > > 2 locks held by swapper/1/0: > #0: ffff888147474908 (&group->lock){..-.}-{2:2}, at: _snd_pcm_stream_lock_irqsave+0x9f/0xd0 sound/core/pcm_native.c:170 > #1: ffff88801b2b3130 (&runtime->sleep){..-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:137 > > stack backtrace: > CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.11.0-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+0xfa/0x151 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/0x730 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:4960 > __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:378 > __run_hrtimer kernel/time/hrtimer.c:1519 [inline] > __hrtimer_run_queues+0x609/0xe40 kernel/time/hrtimer.c:1583 > hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1600 > __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:111 [inline] > RIP: 0010:acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:516 > Code: dd 38 6e f8 84 db 75 ac e8 54 32 6e f8 e8 0f 1c 74 f8 e9 0c 00 00 00 e8 45 32 6e f8 0f 00 2d 4e 4a c5 00 e8 39 32 6e f8 fb f4 <9c> 5b 81 e3 00 02 00 00 fa 31 ff 48 89 de e8 14 3a 6e f8 48 85 db > RSP: 0018:ffffc90000d47d18 EFLAGS: 00000293 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff8880115c3780 RSI: ffffffff89052537 RDI: 0000000000000000 > RBP: ffff888141127064 R08: 0000000000000001 R09: 0000000000000001 > R10: ffffffff81794168 R11: 0000000000000000 R12: 0000000000000001 > R13: ffff888141127000 R14: ffff888141127064 R15: ffff888143331804 > acpi_idle_enter+0x361/0x500 drivers/acpi/processor_idle.c:647 > 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 > cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:397 > start_secondary+0x274/0x350 arch/x86/kernel/smpboot.c:272 > secondary_startup_64_no_verify+0xb0/0xbb >This looks very odd, only thing I can think of is someone >doing >poll_wait() twice with different entries but for the same >waitqueue head. > Hello Jens Axboe here poll_wait() twice in waitqueue head 'runtime->sleep' in sound/core/oss/pcm_oss.c static __poll_t snd_pcm_oss_poll(struct file *file, poll_table * wait) { ........... if (psubstream != NULL) { struct snd_pcm_runtime *runtime = psubstream->runtime; poll_wait(file, &runtime->sleep, wait); snd_pcm_stream_lock_irq(psubstream); if (runtime->status->state != SNDRV_PCM_STATE_DRAINING && (runtime->status->state != SNDRV_PCM_STATE_RUNNING || snd_pcm_oss_playback_ready(psubstream))) mask |= EPOLLOUT | EPOLLWRNORM; snd_pcm_stream_unlock_irq(psubstream); } if (csubstream != NULL) { struct snd_pcm_runtime *runtime = csubstream->runtime; snd_pcm_state_t ostate; poll_wait(file, &runtime->sleep, wait); snd_pcm_stream_lock_irq(csubstream); .......... } I don't know if there are any other drivers that use the same way , can add some judgment in io_poll_double_wake()? >#syz test: git://git.kernel.dk/linux-block syzbot-test > >-- >Jens Axboe
