Re: HVM bug: system crashes after offline online a vcpu

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Dec 19, 2012 at 05:01:57PM +0000, Wei Liu wrote:
> On Wed, 2012-12-19 at 16:04 +0000, Konrad Rzeszutek Wilk wrote:
> > On Thu, Dec 13, 2012 at 03:12:17PM +0000, Wei Liu wrote:
> > > Hi Konrad
> > > 
> > > I encountered a bug when trying to bring offline a cpu then online it
> > > again in HVM. As I'm not very familiar with HVM stuffs I cannot come up
> > > with a quick fix.
> > 
> > I took your two patches that you posted and they are in v3.8 now.
> > 
> > It seems that there are bugs in the offline/online code thought.
> > 
> > I did this:
> > # echo 0 > /sys/devices/system/cpu/cpu3/online
> > # echo 1 > /sys/devices/system/cpu/cpu3/online
> > 
> > With a PV guest and it blows up (with or without your patches).
> > 
> > Have you seen something similar to this:
> > 
> > [  106.166795] BUG: scheduling while atomic: swapper/2/0/0x00000000
> > [  106.167168] microcode: CPU2 sig=0x206a7, pf=0x2, revision=0x17
> > [  106.167566] Modules linked in: sg sd_mod dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi scsi_mod libcrc32c crc32c radeon fbcon tileblit font bitblit softcursor ttm drm_kms_helper crc32c_intel xen_blkfront xen_netfront xen_fbfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs xen_privcmd [last unloaded: dump_dma]
> > [  106.169286] Pid: 0, comm: swapper/2 Tainted: G           O 3.5.0-rc3upstream-00139-gb1849b3-dirty #1
> 
> Can you tell me which tree you're using? I cannot find cs:gb1849b3 in my
> repository.

Oh, .. that might have been me messing around. I would just do v3.7 and
try that out.
> 
> 
> Wei.
>