Re: [Qemu-devel] glib mainloop breaks virtfs

[Aneesh Kumar K.V]

On Tue, 06 Sep 2011 09:31:32 -0500, Anthony Liguori <address@hidden> wrote:
> On 09/06/2011 06:22 AM, Gerd Hoffmann wrote:
> > Hi,
> >
> > virtfs stopped working for me in master, the guest (fedora 15) just
> > hangs at boot when mounting the virtfs filesystems. Bisecting points to
> > this commit:
> >
> > rincewind kraxel ~/projects/qemu ((69e5bb6...)|BISECTING)# git bisect good
> > 4d88a2ac8643265108ef1fb47ceee5d7b28e19f2 is the first bad commit
> > commit 4d88a2ac8643265108ef1fb47ceee5d7b28e19f2
> > Author: Anthony Liguori <address@hidden>
> > Date: Mon Aug 22 08:12:53 2011 -0500
> >
> > main: switch qemu_set_fd_handler to g_io_add_watch
> 
> The v9fs code uses qemu_set_fd_handler to trigger coroutines.  I suspect 
> this is not going to be a fun one to debug.
> 
> This changeset changes the ordering of when callbacks are fired so it 
> may be triggering a latent bug in the coroutine usage in virtio-9p. 
> Aneesh, can you take a look at it?
> 

With master 344eecf6995f4a0ad1d887cec922f6806f91a3f8 I am getting SIGABRT 

*** glibc detected *** /home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64: 
corrupted double-linked list: 0x000000000154ed60 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x76bb6)[0x7ffff5a9abb6]
/lib/x86_64-linux-gnu/libc.so.6(+0x7a931)[0x7ffff5a9e931]
/lib/x86_64-linux-gnu/libc.so.6(__libc_malloc+0x6e)[0x7ffff5aa031e]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x4f3b36]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_malloc+0x23)[0x7ffff7524a63]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_io_channel_unix_new+0x15)[0x7ffff7562635]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x46a019]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x4ed2e3]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x4ed3d3]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x4ed7a3]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x4edc7e]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x5e10ef]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x46ad04]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x46a73d]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x46b0ff]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x5d6740]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x5d6cbc]
/home/kvaneesh/bin-local/qemu-9p/bin/qemu-system-x86_64[0x5a9996]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x6d8c)[0x7ffff5dbed8c]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7ffff5b0a04d]

gdb stack
Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff1ec8700 (LWP 4384)]
0x00007ffff5a57d05 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) where
#0  0x00007ffff5a57d05 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff5a5bab6 in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff5a90d7b in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x00007ffff5a9abb6 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x00007ffff5a9e931 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#5  0x00007ffff5aa031e in malloc () from /lib/x86_64-linux-gnu/libc.so.6
#6  0x00000000004f3b36 in malloc_and_trace (n_bytes=120) at 
/home/opensource/sources/qemu/qemu-upstream/vl.c:2146
#7  0x00007ffff7524a63 in g_malloc () from 
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#8  0x00007ffff7562635 in g_io_channel_unix_new () from 
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#9  0x000000000046a019 in qemu_set_fd_handler (fd=18, fd_read=0x4ed205 
<virtio_pci_host_notifier_read>, fd_write=0, opaque=0x14d7190)
    at /home/opensource/sources/qemu/qemu-upstream/iohandler.c:139
#10 0x00000000004ed2e3 in virtio_pci_set_host_notifier_fd_handler 
(proxy=0x14d6440, n=0, assign=true)
    at /home/opensource/sources/qemu/qemu-upstream/hw/virtio-pci.c:206
#11 0x00000000004ed3d3 in virtio_pci_start_ioeventfd (proxy=0x14d6440) at 
/home/opensource/sources/qemu/qemu-upstream/hw/virtio-pci.c:234
#12 0x00000000004ed7a3 in virtio_ioport_write (opaque=0x14d6440, addr=18, val=7)
    at /home/opensource/sources/qemu/qemu-upstream/hw/virtio-pci.c:329
#13 0x00000000004edc7e in virtio_pci_config_writeb (opaque=0x14d6440, addr=18, 
val=7)
    at /home/opensource/sources/qemu/qemu-upstream/hw/virtio-pci.c:446
#14 0x00000000005e10ef in memory_region_iorange_write (iorange=0x14d68e8, 
offset=18, width=1, data=7)
    at /home/opensource/sources/qemu/qemu-upstream/memory.c:421
#15 0x000000000046ad04 in ioport_writeb_thunk (opaque=0x14d68e8, addr=49234, 
data=7)
    at /home/opensource/sources/qemu/qemu-upstream/ioport.c:210
#16 0x000000000046a73d in ioport_write (index=0, address=49234, data=7) at 
/home/opensource/sources/qemu/qemu-upstream/ioport.c:81
#17 0x000000000046b0ff in cpu_outb (addr=49234, val=7 '\a') at 
/home/opensource/sources/qemu/qemu-upstream/ioport.c:273
#18 0x00000000005d6740 in kvm_handle_io (port=49234, data=0x7ffff7ff3000, 
direction=1, size=1, count=1)
    at /home/opensource/sources/qemu/qemu-upstream/kvm-all.c:834
#19 0x00000000005d6cbc in kvm_cpu_exec (env=0x123a430) at 
/home/opensource/sources/qemu/qemu-upstream/kvm-all.c:976
#20 0x00000000005a9996 in qemu_kvm_cpu_thread_fn (arg=0x123a430) at 
/home/opensource/sources/qemu/qemu-upstream/cpus.c:661
#21 0x00007ffff5dbed8c in start_thread () from 
/lib/x86_64-linux-gnu/libpthread.so.0
#22 0x00007ffff5b0a04d in clone () from /lib/x86_64-linux-gnu/libc.so.6
#23 0x0000000000000000 in ?? ()
(gdb) 

Reverting 4d88a2ac8643265108ef1fb47ceee5d7b28e19f2 fixes the issue. This
is on ubuntu 11.04.

-aneesh