From: Eryu Guan <eguan@linux.alibaba.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [BUG qemu 4.0] segfault when unplugging virtio-blk-pci device
Date: Thu, 2 Jan 2020 10:08:50 +0800 [thread overview]
Message-ID: <20200102020850.GB41863@e18g06458.et15sqa> (raw)
In-Reply-To: <20191231115136.7b967604@Igors-MacBook-Pro>
On Tue, Dec 31, 2019 at 11:51:35AM +0100, Igor Mammedov wrote:
> On Tue, 31 Dec 2019 18:34:34 +0800
> Eryu Guan <eguan@linux.alibaba.com> wrote:
>
> > Hi,
> >
> > I'm using qemu 4.0 and hit segfault when tearing down kata sandbox, I
> > think it's because io completion hits use-after-free when device is
> > already gone. Is this a known bug that has been fixed? (I went through
> > the git log but didn't find anything obvious).
> >
> > gdb backtrace is:
> >
> > Core was generated by `/usr/local/libexec/qemu-kvm -name sandbox-5b8df8c6c6901c3c0a9b02879be10fe8d69d6'.
> > Program terminated with signal 11, Segmentation fault.
> > #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903
> > 903 return obj->class;
> > (gdb) bt
> > #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903
> > #1 0x0000558a2c009e9b in virtio_notify_vector (vdev=0x558a2e7751d0,
> > vector=<optimized out>) at /usr/src/debug/qemu-4.0/hw/virtio/virtio.c:1118
> > #2 0x0000558a2bfdcb1e in virtio_blk_discard_write_zeroes_complete (
> > opaque=0x558a2f2fd420, ret=0)
> > at /usr/src/debug/qemu-4.0/hw/block/virtio-blk.c:186
> > #3 0x0000558a2c261c7e in blk_aio_complete (acb=0x558a2eed7420)
> > at /usr/src/debug/qemu-4.0/block/block-backend.c:1305
> > #4 0x0000558a2c3031db in coroutine_trampoline (i0=<optimized out>,
> > i1=<optimized out>) at /usr/src/debug/qemu-4.0/util/coroutine-ucontext.c:116
> > #5 0x00007f45b2f8b080 in ?? () from /lib64/libc.so.6
> > #6 0x00007fff9ed75780 in ?? ()
> > #7 0x0000000000000000 in ?? ()
> >
> > It seems like qemu was completing a discard/write_zero request, but
> > parent BusState was already freed & set to NULL.
> >
> > Do we need to drain all pending request before unrealizing virtio-blk
> > device? Like the following patch proposed?
> >
> > https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg02945.html
> >
> > If more info is needed, please let me know.
>
> may be this will help: https://patchwork.kernel.org/patch/11213047/
Yeah, this looks promising! I'll try it out (though it's a one-time
crash for me). Thanks!
Eryu
next prev parent reply other threads:[~2020-01-02 2:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-31 10:34 [BUG qemu 4.0] segfault when unplugging virtio-blk-pci device Eryu Guan
2019-12-31 10:51 ` Igor Mammedov
2020-01-02 2:08 ` Eryu Guan [this message]
2020-01-07 13:06 ` Eryu Guan
2020-01-07 14:01 ` Julia Suvorova
2020-01-08 1:54 ` Eryu Guan
2020-01-09 4:58 ` Eryu Guan
2020-01-13 16:38 ` Stefan Hajnoczi
2020-01-14 2:50 ` Eryu Guan
2020-01-14 16:16 ` Stefan Hajnoczi
2020-01-19 8:13 ` Eryu Guan
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