[libvirt] [PATCH 5/6] qemu: Leave cpuset.mems in parent cgroup alone

[Eric Blake]

On 12/15/2014 12:58 AM, Martin Kletzander wrote:
> Instead of setting the value of cpuset.mems once when the domain starts
> and then re-calculating the value every time we need to change the child
> cgroup values, leave the cgroup alone and rather set the child data
> every time there is new cgroup created.  We don't leave any task in the
> parent group anyway.  This will ease both current and future code.
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/qemu/qemu_cgroup.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++--
>  src/qemu/qemu_driver.c | 59 +++++++++++++++-----------------------------
>  2 files changed, 85 insertions(+), 41 deletions(-)

This patch causes libvirtd to segfault on startup:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffda116700 (LWP 15311)]
0x00007ffff7400890 in virCgroupPathOfController (group=0x0, controller=2,
    key=0x7ffff768a019 "tasks", path=0x7fffda115b30) at
util/vircgroup.c:1867
1867	    if (group->controllers[controller].mountPoint == NULL) {
(gdb) bt
#0  0x00007ffff7400890 in virCgroupPathOfController (group=0x0,
controller=2,
    key=0x7ffff768a019 "tasks", path=0x7fffda115b30) at
util/vircgroup.c:1867
#1  0x00007ffff73fe4db in virCgroupGetValueStr (group=0x0, controller=2,
    key=0x7ffff768a019 "tasks", value=0x7fffda115b80) at
util/vircgroup.c:751
#2  0x00007ffff7405673 in virCgroupHasEmptyTasks (cgroup=0x0, controller=2)
    at util/vircgroup.c:3935
#3  0x00007fffdc79c687 in qemuRestoreCgroupState (vm=0x7fffd41dd8d0)
    at qemu/qemu_cgroup.c:802
#4  0x00007fffdc79c80c in qemuConnectCgroup (driver=0x7fffd4152ae0,
    vm=0x7fffd41dd8d0) at qemu/qemu_cgroup.c:848
#5  0x00007fffdc7b8553 in qemuProcessReconnect (opaque=0x7fffd41da150)
    at qemu/qemu_process.c:3616
#6  0x00007ffff7469830 in virThreadHelper (data=0x7fffd41c5b00)
    at util/virthread.c:197
#7  0x00007ffff3e65ee5 in start_thread (arg=0x7fffda116700)
    at pthread_create.c:309
#8  0x00007ffff3b94b8d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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