Re: [Xen-users] Crashes on image file backed VMs

Re: [Xen-users] Crashes on image file backed VMs

[Ian Campbell]

On Sat, 2015-12-19 at 11:18 +0000, Andre Fucs wrote:
> Ian,
> 
> Thanks for the reply. 
> 
> coredumpctl gbd PID_OF_PROCESS printed the following:

A SIGBUS in QEMU's blk_handle_requests, how exciting!

Copying xen-devel and some relevant maintainers, start of thread is
http://lists.xen.org/archives/html/xen-users/2015-12/msg00073.html
From that, this is Xen 4.5.1 on arch Linux.

Andre, could you take a look under /var/log/xen for logs relating to a
domain to which this has happened, in particular the qemu log. It would
also be useful to see the corresponding guest cfg file I expect.

Ian.

> [...]

> warning: Could not load shared library symbols for linux-vdso.so.1.
> Do you need "set solib-search-path" or "set sysroot"?
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/usr/lib/libthread_db.so.1".
> Core was generated by `/usr/lib/xen/bin/qemu-system-i386 -xen-domid 11
> -chardev                                                                
>              socket,id=libxl-cmd,pa'.
> Program terminated with signal SIGBUS, Bus error.
> #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0)
>     at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-
> xen/hw/block/xen_disk.c:699
> 699     rp = blkdev->rings.common.sring->req_prod;
> [Current thread is 1 (Thread 0x7f68ed0909c0 (LWP 10134))]
> (gdb) bt
> #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0) at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/hw/block/xen_disk.c:699
> #1  blk_bh (opaque=0x55b277c49ab0) at /home/xafucs/xen/src/xen-
> 4.5.1/tools/qemu-xen/hw/block/xen_disk.c:738
> #2  0x000055b2769e62d3 in aio_bh_poll (ctx=ctx@entry=0x55b277c34600) at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/async.c:81
> #3  0x000055b2769e5efc in aio_poll (ctx=0x55b277c34600, blocking=blocking
> @entry=false) at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/aio-
> posix.c:188
> #4  0x000055b2769e6103 in aio_ctx_dispatch (source=<optimized out>,
> callback=<optimized out>, user_data=<optimized out>)
>     at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/async.c:211
> #5  0x00007f68ebf98dc7 in g_main_context_dispatch () from
> /usr/lib/libglib-2.0.so.0
> #6  0x000055b276b066b1 in glib_pollfds_poll () at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:190
> #7  os_host_main_loop_wait (timeout=<optimized out>) at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:235
> #8  main_loop_wait (nonblocking=<optimized out>) at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:484
> #9  0x000055b276b77e09 in main_loop () at /home/xafucs/xen/src/xen-
> 4.5.1/tools/qemu-xen/vl.c:2056
> #10 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized
> out>) at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/vl.c:4535
> (gdb) thread 1
> [Switching to thread 1 (Thread 0x7f68ed0909c0 (LWP 10134))]
> #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0) at
> /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/hw/block/xen_disk.c:699
> 699     rp = blkdev->rings.common.sring->req_prod;
> 
> 

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Re: [Xen-users] Crashes on image file backed VMs

[Stefano Stabellini]

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On Mon, 4 Jan 2016, Ian Campbell wrote:
> On Sat, 2015-12-19 at 11:18 +0000, Andre Fucs wrote:
> > Ian,
> >
> > Thanks for the reply.
> >
> > coredumpctl gbd PID_OF_PROCESS printed the following:
>
> A SIGBUS in QEMU's blk_handle_requests, how exciting!
>
> Copying xen-devel and some relevant maintainers, start of thread is
> http://lists.xen.org/archives/html/xen-users/2015-12/msg00073.html
> >From that, this is Xen 4.5.1 on arch Linux.
>
> Andre, could you take a look under /var/log/xen for logs relating to a
> domain to which this has happened, in particular the qemu log. It would
> also be useful to see the corresponding guest cfg file I expect.

It's good that you can reproduce the bug.

What kernel are you using in Dom0?
What underlying storage are you using for the guest VMs (local disk,
nfs, iscsi, etc)?

Can you reproduce the bug with a more recent QEMU? For example:

git://git.qemu.org/qemu.git v2.5.0

no need to update Xen for this test, just compile QEMU separately, I
just do:

./configure --enable-xen --target-list=i386-softmmu --disable-kvm
make
cp i386-softmmu/qemu-system-i386 /usr/lib/xen/bin

Thanks for your help!


> > [...]
>
> > warning: Could not load shared library symbols for linux-vdso.so.1.
> > Do you need "set solib-search-path" or "set sysroot"?
> > [Thread debugging using libthread_db enabled]
> > Using host libthread_db library "/usr/lib/libthread_db.so.1".
> > Core was generated by `/usr/lib/xen/bin/qemu-system-i386 -xen-domid 11
> > -chardev                                                                
> >              socket,id=libxl-cmd,pa'.
> > Program terminated with signal SIGBUS, Bus error.
> > #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0)
> >     at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-
> > xen/hw/block/xen_disk.c:699
> > 699     rp = blkdev->rings.common.sring->req_prod;
> > [Current thread is 1 (Thread 0x7f68ed0909c0 (LWP 10134))]
> > (gdb) bt
> > #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0) at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/hw/block/xen_disk.c:699
> > #1  blk_bh (opaque=0x55b277c49ab0) at /home/xafucs/xen/src/xen-
> > 4.5.1/tools/qemu-xen/hw/block/xen_disk.c:738
> > #2  0x000055b2769e62d3 in aio_bh_poll (ctx=ctx@entry=0x55b277c34600) at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/async.c:81
> > #3  0x000055b2769e5efc in aio_poll (ctx=0x55b277c34600, blocking=blocking
> > @entry=false) at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/aio-
> > posix.c:188
> > #4  0x000055b2769e6103 in aio_ctx_dispatch (source=<optimized out>,
> > callback=<optimized out>, user_data=<optimized out>)
> >     at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/async.c:211
> > #5  0x00007f68ebf98dc7 in g_main_context_dispatch () from
> > /usr/lib/libglib-2.0.so.0
> > #6  0x000055b276b066b1 in glib_pollfds_poll () at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:190
> > #7  os_host_main_loop_wait (timeout=<optimized out>) at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:235
> > #8  main_loop_wait (nonblocking=<optimized out>) at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/main-loop.c:484
> > #9  0x000055b276b77e09 in main_loop () at /home/xafucs/xen/src/xen-
> > 4.5.1/tools/qemu-xen/vl.c:2056
> > #10 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized
> > out>) at /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/vl.c:4535
> > (gdb) thread 1
> > [Switching to thread 1 (Thread 0x7f68ed0909c0 (LWP 10134))]
> > #0  0x000055b276a618fd in blk_handle_requests (blkdev=0x55b277c49ab0) at
> > /home/xafucs/xen/src/xen-4.5.1/tools/qemu-xen/hw/block/xen_disk.c:699
> > 699     rp = blkdev->rings.common.sring->req_prod;
> >
> >
> 

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