[Bug 1867786] Re: Qemu PPC64 freezes with multi-core CPU

[Thomas Huth]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting older bugs to "Incomplete" now.

If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1867786

Title:
  Qemu PPC64 freezes with multi-core CPU

Status in QEMU:
  Incomplete

Bug description:
  I installed Debian 10 on a Qemu PPC64 VM running with the following
  flags:

  qemu-system-ppc64 \
       -nographic -nodefaults -monitor pty -serial stdio \
       -M pseries -cpu POWER9 -smp cores=4,threads=1 -m 4G \
       -drive file=debian-ppc64el-qemu.qcow2,format=qcow2,if=virtio \
       -netdev user,id=network01,$ports -device rtl8139,netdev=network01 \

  
  Within a couple minutes on any operation (could be a Go application or simply 
changing the hostname with hostnamectl, the VM freezes and prints this on the 
console:

  ```
  root@debian:~# [  950.428255] rcu: INFO: rcu_sched self-detected stall on CPU
  [  950.428453] rcu:     3-....: (5318 ticks this GP) 
idle=8e2/1/0x4000000000000004 softirq=5957/5960 fqs=2544
  [  976.244481] watchdog: BUG: soft lockup - CPU#3 stuck for 23s! [zsh:462]

  Message from syslogd@debian at Mar 17 11:35:24 ...
   kernel:[  976.244481] watchdog: BUG: soft lockup - CPU#3 stuck for 23s! 
[zsh:462]
  [  980.110018] rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: 
{ 3-... } 5276 jiffies s: 93 root: 0x8/.
  [  980.111177] rcu: blocking rcu_node structures:
  [ 1013.442268] rcu: INFO: rcu_sched self-detected stall on CPU
  [ 1013.442365] rcu:     3-....: (21071 ticks this GP) 
idle=8e2/1/0x4000000000000004 softirq=5957/5960 fqs=9342
  ```

  If I change to 1 core on the command line, I haven't seen these
  freezes.

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