I have some reproducible-ish segfaults in qemu 2.7.0 (built from source)
running under ubuntu 16.04, on a quad-core i7 Mac Mini Server.
I can reproduce these problems on a different Mac Mini, and I also
replaced the RAM on mine, so I'm sure it's not hardware related.
It's somewhat painful to reproduce (taking about 30 minutes each
attempt, and using a lot of network bandwidth).
This is using packer (packer.io) to create a VM and then using ansible
to do a whole load of package installation and provisioning inside that
VM. packer starts qemu with a user-mode network interface.
If I part-build the VM, I can continue the build by restarting it under
gdb and qemu directly at the command line, and get a backtrace. Here's
the first one:
Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault.
0x00007ffff6a1bb5b in _int_free (av=0x7ffff6d5fb20 <main_arena>,
p=<optimised out>, have_lock=0) at malloc.c:4006
4006 malloc.c: No such file or directory.
(gdb) bt
#0 0x00007ffff6a1bb5b in _int_free (av=0x7ffff6d5fb20 <main_arena>,
p=<optimised out>, have_lock=0)
at malloc.c:4006
#1 0x00007ffff6a1fabc in __GI___libc_free (mem=<optimised out>) at
malloc.c:2969
#2 0x00005555559a6c0f in tcp_close (tp=tp@entry=0x555556621ed0) at
slirp/tcp_subr.c:334
#3 0x00005555559a6c8f in tcp_drop (tp=tp@entry=0x555556621ed0,
err=<optimised out>) at slirp/tcp_subr.c:298
#4 0x00005555559a816b in tcp_timers (timer=<optimised out>,
tp=0x555556621ed0) at slirp/tcp_timer.c:179
#5 tcp_slowtimo (slirp=slirp@entry=0x55555658ecf0) at slirp/tcp_timer.c:89
#6 0x00005555559a0be8 in slirp_pollfds_poll (pollfds=0x555556531f20,
select_error=select_error@entry=0)
at slirp/slirp.c:576
#7 0x00005555559d4b0c in main_loop_wait (nonblocking=<optimised out>)
at main-loop.c:508
#8 0x000055555573fea1 in main_loop () at vl.c:1908
#9 main (argc=<optimised out>, argv=<optimised out>, envp=<optimised
out>) at vl.c:4604
(gdb)
So:
* Is this of interest?
* If so, what additional gdb output would you like me to provide?
* If developers want to reproduce this, let me know and I can probably
send the VM qcow2 file and/or packer source privately off-list [I need
to check permission for that]
Thanks,
Brian Candler.
