Message-ID: <CACT4Y+a_RYa0qTi1jNJv4_cu51zmzqgNT=WgQco3nxhTVzDRWw@mail.gmail.com>
Date:   Fri, 10 Jun 2022 10:33:37 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     syzbot <syzbot+4bff2788f64e121fefcf@...kaller.appspotmail.com>
Cc:     herbert@...dor.apana.org.au, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-next@...r.kernel.org,
        linux@...inikbrodowski.net, mpm@...enic.com, sfr@...b.auug.org.au,
        syzkaller-bugs@...glegroups.com, Jason Wang <jasowang@...hat.com>,
        Laurent Vivier <lvivier@...hat.com>
Subject: Re: [syzbot] linux-next boot error: INFO: task hung in
 add_early_randomness (2)

On Thu, 2 Jun 2022 at 09:39, syzbot
<syzbot+4bff2788f64e121fefcf@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    2e776ccffa84 Add linux-next specific files for 20220602
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14226a35f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5266d49aa5c20076
> dashboard link: https://syzkaller.appspot.com/bug?extid=4bff2788f64e121fefcf
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+4bff2788f64e121fefcf@...kaller.appspotmail.com

Assume this is also fixed by:

#syz fix: virtio-rng: make device ready before making request

> INFO: task swapper/0:1 blocked for more than 143 seconds.
>       Not tainted 5.18.0-next-20220602-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:swapper/0       state:D stack:23832 pid:    1 ppid:     0 flags:0x00004000
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:5116 [inline]
>  __schedule+0xa06/0x4b40 kernel/sched/core.c:6428
>  schedule+0xd2/0x1f0 kernel/sched/core.c:6500
>  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6559
>  __mutex_lock_common kernel/locking/mutex.c:679 [inline]
>  __mutex_lock+0xa70/0x1350 kernel/locking/mutex.c:747
>  add_early_randomness+0x1a/0x170 drivers/char/hw_random/core.c:69
>  hwrng_register+0x399/0x510 drivers/char/hw_random/core.c:599
>  virtrng_scan+0x37/0x90 drivers/char/hw_random/virtio-rng.c:205
>  virtio_dev_probe+0x639/0x910 drivers/virtio/virtio.c:313
>  call_driver_probe drivers/base/dd.c:562 [inline]
>  really_probe+0x23e/0xb90 drivers/base/dd.c:641
>  __driver_probe_device+0x338/0x4d0 drivers/base/dd.c:774
>  driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:804
>  __driver_attach+0x22d/0x550 drivers/base/dd.c:1173
>  bus_for_each_dev+0x147/0x1d0 drivers/base/bus.c:301
>  bus_add_driver+0x422/0x640 drivers/base/bus.c:618
>  bus_add_driver+0x422/0x640 drivers/base/bus.c:618
>  driver_register+0x220/0x3a0 drivers/base/driver.c:240
>  do_one_initcall+0x103/0x660 init/main.c:1300
>  do_initcall_level init/main.c:1375 [inline]
>  do_initcalls init/main.c:1391 [inline]
>  do_basic_setup init/main.c:1410 [inline]
>  kernel_init_freeable+0x6b1/0x73a init/main.c:1617
>  kernel_init+0x1a/0x1d0 init/main.c:1506
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
>  </TASK>
>
> Showing all locks held in the system:
> 2 locks held by swapper/0/1:
>  #0: ffff88801b377170 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:835 [inline]
>  #0: ffff88801b377170 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1064 [inline]
>  #0: ffff88801b377170 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x222/0x550 drivers/base/dd.c:1172
>  #1: ffffffff8c841068 (reading_mutex){+.+.}-{3:3}, at: add_early_randomness+0x1a/0x170 drivers/char/hw_random/core.c:69
> 2 locks held by kworker/u4:0/8:
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
>  #0: ffff888010c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x87a/0x1610 kernel/workqueue.c:2260
>  #1: ffffc900000d7da8 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264
> 2 locks held by pr/ttyS0/16:
> 1 lock held by khungtaskd/28:
>  #0: ffffffff8bd86aa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6491
> 1 lock held by hwrng/755:
>  #0: ffffffff8c841068 (reading_mutex){+.+.}-{3:3}, at: hwrng_fillfn+0x141/0x370 drivers/char/hw_random/core.c:503
>
> =============================================
>
>
>
> ---
> 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.
>
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