On 2/28/21 7:08 PM, Zhang, Qiang wrote: > > > ________________________________________ > 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()? Right, that's what my post-email investigation led to as well, hence I queued this one up: https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-worker.v4&id=4a0a6fd611f5109bcfab4a95db836bb27131e3be -- Jens Axboe
