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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Tue, 14 Jun 2022 10:50:33 +0200
Message-ID: <CACT4Y+YF+Jo5kgjqBouw3NnKUq0pxF3geJhbACpN3QgtHSj8kQ@mail.gmail.com>
Subject: Re: [syzbot] upstream boot error: INFO: task hung in hwrng_register
To:     Jason Wang <jasowang@redhat.com>
Cc:     syzbot <syzbot+6da75abeed821109137b@syzkaller.appspotmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        linux-crypto@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux@dominikbrodowski.net, llvm@lists.linux.dev, mpm@selenic.com,
        syzkaller-bugs@googlegroups.com,
        Laurent Vivier <lvivier@redhat.com>
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On Tue, 14 Jun 2022 at 10:07, Jason Wang <jasowang@redhat.com> wrote:
> > On Sat, 4 Jun 2022 at 10:46, syzbot
> > <syzbot+6da75abeed821109137b@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    032dcf09e2bf Merge tag 'gpio-fixes-for-v5.19-rc1' of git:/..
> > > git tree:       upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=14409a93f00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=99f457384a4fea79
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=6da75abeed821109137b
> > > compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, 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+6da75abeed821109137b@syzkaller.appspotmail.com
> >
> > +Jason, Laurent
> >
> > This started appearing at the same time as 'task hung in
> > add_early_randomness" bug reports:
> > https://syzkaller.appspot.com/bug?id=256d08cc261a3c38832064a33df4c928b3cd0ef0
> > https://syzkaller.appspot.com/bug?id=be1d99e09e499aed3939dc678718371984104e5c
> > https://syzkaller.appspot.com/bug?id=1cd11df5d984c694e3e7fc9fe271389b2340bed0
> > https://syzkaller.appspot.com/bug?id=35496bafab4c3f81f0b0d6d72c69787300629740
> >
> > Is this also fixed by "virtio-rng: make device ready before making
> > request" patch?
>
> Yes, I think so.
>
> Thanks

Let's tell the bot so that it reports such bugs in future:

#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-syzkaller-13760-g032dcf09e2bf #0
> > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > > task:swapper/0       state:D stack:21080 pid:    1 ppid:     0 flags:0x00004000
> > > Call Trace:
> > >  <TASK>
> > >  context_switch kernel/sched/core.c:5116 [inline]
> > >  __schedule+0x957/0xec0 kernel/sched/core.c:6428
> > >  schedule+0xeb/0x1b0 kernel/sched/core.c:6500
> > >  schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6559
> > >  __mutex_lock_common+0xecf/0x26c0 kernel/locking/mutex.c:679
> > >  __mutex_lock kernel/locking/mutex.c:747 [inline]
> > >  mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
> > >  add_early_randomness drivers/char/hw_random/core.c:69 [inline]
> > >  hwrng_register+0x3bf/0x680 drivers/char/hw_random/core.c:599
> > >  virtrng_scan+0x3e/0x90 drivers/char/hw_random/virtio-rng.c:205
> > >  virtio_dev_probe+0xa03/0xba0 drivers/virtio/virtio.c:313
> > >  call_driver_probe+0x96/0x250
> > >  really_probe+0x220/0x940 drivers/base/dd.c:634
> > >  __driver_probe_device+0x1f4/0x3f0 drivers/base/dd.c:764
> > >  driver_probe_device+0x50/0x240 drivers/base/dd.c:794
> > >  __driver_attach+0x35f/0x5a0 drivers/base/dd.c:1163
> > >  bus_for_each_dev+0x188/0x1f0 drivers/base/bus.c:301
> > >  bus_add_driver+0x32f/0x600 drivers/base/bus.c:618
> > >  bus_add_driver+0x32f/0x600 drivers/base/bus.c:618
> > >  driver_register+0x2e9/0x3e0 drivers/base/driver.c:240
> > >  do_one_initcall+0xbd/0x2b0 init/main.c:1295
> > >  do_initcall_level+0x168/0x218 init/main.c:1368
> > >  do_initcalls+0x4b/0x8c init/main.c:1384
> > >  kernel_init_freeable+0x43a/0x5c3 init/main.c:1610
> > >  kernel_init+0x19/0x2b0 init/main.c:1499
> > >  ret_from_fork+0x1f/0x30
> > >  </TASK>
> > >
> > > Showing all locks held in the system:
> > > 2 locks held by swapper/0/1:
> > >  #0: ffff8881468d4170 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:835 [inline]
> > >  #0: ffff8881468d4170 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1054 [inline]
> > >  #0: ffff8881468d4170 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x353/0x5a0 drivers/base/dd.c:1162
> > >  #1: ffffffff8d24ccc8 (reading_mutex){+.+.}-{3:3}, at: add_early_randomness drivers/char/hw_random/core.c:69 [inline]
> > >  #1: ffffffff8d24ccc8 (reading_mutex){+.+.}-{3:3}, at: hwrng_register+0x3bf/0x680 drivers/char/hw_random/core.c:599
> > > 2 locks held by pr/ttyS0/16:
> > > 1 lock held by khungtaskd/29:
> > >  #0: ffffffff8cb1eee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
> > > 2 locks held by kworker/u4:4/56:
> > >  #0: ffff888011c69138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x796/0xd10 kernel/workqueue.c:2262
> > >  #1: ffffc900013e7d00 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0xd10 kernel/workqueue.c:2264
> > > 1 lock held by hwrng/755:
> > >  #0: ffffffff8d24ccc8 (reading_mutex){+.+.}-{3:3}, at: hwrng_fillfn+0xec/0x470 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@googlegroups.com.
> > >
> > > syzbot will keep track of this issue. See:
> > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > >
> > > --
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> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/0000000000008ea7ac05e09b46a6%40google.com.
> >
>