[Qemu-devel] [Bug 595438] Re: KVM segmentation fault, using SCSI+writeback and linux 2.4 guest

[Коренберг Марк]

valgrind --malloc-fill=0x69 --free-fill=0x11

Process terminating with default action of signal 11 (SIGSEGV)
==00:00:01:03.046 29447==  Access not within mapped region at address 0x11111151
==00:00:01:03.046 29447==    at 0x80B4713: scsi_req_free (scsi-bus.c:153)
==00:00:01:03.047 29447==    by 0x80B186B: scsi_remove_request (scsi-disk.c:86)
==00:00:01:03.047 29447==    by 0x8095280: qcow_aio_write_cb (qcow2.c:640)
==00:00:01:03.047 29447==    by 0x80849BE: posix_aio_process_queue 
(posix-aio-compat.c:460)
==00:00:01:03.047 29447==    by 0x8084A76: posix_aio_read 
(posix-aio-compat.c:501)
==00:00:01:03.047 29447==    by 0x805E3D7: main_loop_wait (vl.c:1300)
==00:00:01:03.047 29447==    by 0x806EA83: kvm_main_loop (qemu-kvm.c:1710)
==00:00:01:03.047 29447==    by 0x8060A72: main (vl.c:1340)

It seems, that  0x11111151 - is a pointer inside already freed region :(

http://dl3.ideco-software.ru/IdecoICS/IdecoICS_342_123.iso
http://dl1.ideco-software.ru/IdecoICS/IdecoICS_342_123.iso
http://dl2.ideco-software.ru/IdecoICS/IdecoICS_342_123.iso

(If you get 404, please inform me, I will give new links.)

Instructions how to reproduce:
after boot: type "setup100hz action=install p=1" and press Enter. Line should 
look as:

boot:  setup100hz  action=install  p=1

In each experiment
You need fresh (empty) "qemu-img create -f qcow2 8G" image (preferable in tmpfs 
filesystem) Image will be expanded nearly to 1.5 Gb.  I have VMX-enabled Intel 
processor and 32-bit kernel. KVM was built just using ./configure && make

command:
qemu-system-x86_64 -drive file=xxx.img,cache=writeback,if=scsi -cdrom 
IdecoICS_342_123.iso

It will show some dialogs while copying files after which it will go to reboot 
if all OK. 
In our case: somewhere during copying files, kvm will do segmentation fault, 
before rebooting of VM.

-- 
KVM segmentation fault, using SCSI+writeback and linux 2.4 guest
https://bugs.launchpad.net/bugs/595438
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Status in QEMU: Confirmed

Bug description:
I Use Ubuntu 32 bit 10.04 with standard KVM.
I have Intel E7600  @ 3.06GHz processor with VMX

In this system I Run:
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin 
QEMU_AUDIO_DRV=none /usr/bin/kvm -M pc-0.12 -enable-kvm -m 256 -smp 1 -name 
spamsender -uuid b9cacd5e-08f7-41fd-78c8-89cec59af881 -chardev 
socket,id=monitor,path=/var/lib/libvirt/qemu/spamsender.monitor,server,nowait 
-monitor chardev:monitor -boot d -drive 
file=/mnt/megadiff/cdiso_400_130.iso,if=ide,media=cdrom,index=2 -drive 
file=/home/mmarkk/spamsender2.img,if=scsi,index=0,format=qcow2,cache=writeback 
-net nic,macaddr=00:00:00:00:00:00,vlan=0,name=nic.0 -net tap,vlan=0,name=tap.0 
-chardev pty,id=serial0 -serial chardev:serial0 -parallel none -usb -vnc 
127.0.0.1:0 -vga cirrus

.iso image contain custom distro of 2.4-linux kernel based system. During 
install process (when .tar.gz actively unpacked), kvm dead with segmentation 
fault.

And ONLY when I choose scsi virtual disk and writeback simultaneously. 
But, writeback+ide, writethrough+scsi works OK.

I use qcow2. It seems, that qcow does not have such problems.

Virtual machine get down at random time during file copy. It seems, when qcow2 
file size need to be expanded.