From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: HVM bug: system crashes after offline online a vcpu Date: Wed, 19 Dec 2012 16:18:22 +0000 Message-ID: <1355933902.10526.27.camel@iceland> References: <1355411537.8376.52.camel@iceland> <20121219160455.GA12077@phenom.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121219160455.GA12077@phenom.dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: wei.liu2@citrix.com, "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org 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 > [ 106.170152] Call Trace: > [ 106.170598] [] __schedule_bug+0x4d/0x60 > [ 106.171042] [] __schedule+0x69c/0x760 > [ 106.171469] [] schedule+0x24/0x70 > [ 106.171890] [] cpu_idle+0xc9/0xe0 > [ 106.172309] [] ? xen_irq_enable_direct_reloc+0x4/0x4 > [ 106.172726] [] cpu_bringup_and_idle+0xe/0x10 > [ 106.174533] BUG: scheduling while atomic: swapper/2/0/0x00000000 > ? > IIRC I didn't see this. I was using your xen.git kernel tree, not the upstream one. The PV path was fixed after applying my patch and the HVM path I didn't have much idea. I didn't play much with online/offline after fixing what I could fix. Let me play with upstream kernel and give you some feedback. Wei