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Date: Tue, 30 Oct 2012 09:32:42 +0100
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20121030083242.GC9918@stefanha-thinkpad.redhat.com>
References: <508E8E21.6080406@dlhnet.de>
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In-Reply-To: <508E8E21.6080406@dlhnet.de>
Subject: Re: [Qemu-devel] Ubuntu/Debian Installer + Virtio-SCSI -> Bad ram
 pointer
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To: Peter Lieven <pl@dlhnet.de>
Cc: ronnie sahlberg <ronniesahlberg@gmail.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>

On Mon, Oct 29, 2012 at 03:09:37PM +0100, Peter Lieven wrote:
> Hi,

Bug subject should be virtio-blk, not virtio-scsi.  virtio-scsi is a
different virtio device type from virtoi-blk and is not present in the
backtrace you posted.

Sounds pedantic but I want to make sure this gets chalked up against the
right device :).

> If I try to Install Ubuntu 12.04 LTS / 12.10 64-bit on a virtio
> storage backend that supports iSCSI
> qemu-kvm crashes reliably with the following error:

Are you using vanilla qemu-kvm-1.2.0 or are there patches applied?

Have you tried qemu-kvm.git/master?

Have you tried a local raw disk image to check whether libiscsi is
involved?

> Bad ram pointer 0x3039303620008000
> 
> This happens directly after the confirmation of the Timezone before
> the Disk is partitioned.
> 
> If I specify  -global virtio-blk-pci.scsi=off in the cmdline this
> does not happen.
> 
> Here is a stack trace:
> 
> Thread 1 (Thread 0x7ffff7fee700 (LWP 8226)):
> #0 0x00007ffff63c0a10 in abort () from /lib/x86_64-linux-gnu/libc.so.6
> No symbol table info available.
> #1 <https://github.com/sahlberg/libiscsi/issues/1>
> 0x00005555557b751d in qemu_ram_addr_from_host_nofail (
> ptr=0x3039303620008000) at /usr/src/qemu-kvm-1.2.0/exec.c:2835
> ram_addr = 0
> #2 <https://github.com/sahlberg/libiscsi/issues/2>
> 0x00005555557b9177 in cpu_physical_memory_unmap (
> buffer=0x3039303620008000, len=4986663671065686081, is_write=1,
> access_len=1) at /usr/src/qemu-kvm-1.2.0/exec.c:3645

buffer and len are ASCII junk.  It appears to be hex digits and it's not
clear where they come from.

It would be interesting to print *elem one stack frame up in #3
virtqueue_fill() to show the iovecs and in/out counts.

> addr1 = 93825009559312
> #3 <https://github.com/sahlberg/libiscsi/issues/3>
> 0x000055555580a9ca in virtqueue_fill (vq=0x5555565da710,
> elem=0x555556722238, len=1, idx=0)
> at /usr/src/qemu-kvm-1.2.0/hw/virtio.c:240
> size = 1
> offset = 0
> i = 0

Stefan