Bug 1674497
Summary: | Memory Hot-unplug fails to remove DIMM | ||||||||
---|---|---|---|---|---|---|---|---|---|
Product: | Red Hat Enterprise Virtualization Manager | Reporter: | Liran Rotenberg <lrotenbe> | ||||||
Component: | ovirt-engine | Assignee: | Rolfe Dlugy-Hegwer <rdlugyhe> | ||||||
Status: | CLOSED CURRENTRELEASE | QA Contact: | meital avital <mavital> | ||||||
Severity: | high | Docs Contact: | |||||||
Priority: | unspecified | ||||||||
Version: | 4.3.1 | CC: | adahms, ahadas, bhe, chayang, jinzhao, juzhang, lrotenbe, mavital, mmizuma, mm-maint, pifang, pkrempa, rbalakri, rdlugyhe, ribarry, royoung, virt-maint, xfu, yuhuang | ||||||
Target Milestone: | ovirt-4.4.2 | Keywords: | Reopened | ||||||
Target Release: | 4.4.2 | ||||||||
Hardware: | x86_64 | ||||||||
OS: | Unspecified | ||||||||
Whiteboard: | |||||||||
Fixed In Version: | Doc Type: | Known Issue | |||||||
Doc Text: |
Previously, hot-unplugging memory on RHEL 8 guests generated a error because the memory DIMM was in use. This prevented the removal of that memory from that VM. To work around this issue, add `movable_node` by setting the virtual machine's kernel command-line parameters, link:https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/system_design_guide/configuring-kernel-command-line-parameters_system-design-guide#setting-kernel-command-line-parameters_configuring-kernel-command-line-parameters[as described here].
|
Story Points: | --- | ||||||
Clone Of: | Environment: | ||||||||
Last Closed: | 2020-10-04 16:34:56 UTC | Type: | Bug | ||||||
Regression: | --- | Mount Type: | --- | ||||||
Documentation: | --- | CRM: | |||||||
Verified Versions: | Category: | --- | |||||||
oVirt Team: | Docs | RHEL 7.3 requirements from Atomic Host: | |||||||
Cloudforms Team: | --- | Target Upstream Version: | |||||||
Embargoed: | |||||||||
Attachments: |
|
Description
Liran Rotenberg
2019-02-11 13:29:47 UTC
Created attachment 1529010 [details]
logs
Hi Liran, the BZ Component field is "edk2", but comment #0 says, "Create a VM(1GB memory, 16 max memory), RHEL8 image, *BIOS*." (emphasis mine). Also, regarding "dmesg.log" from the attachment ("logs.tar.xz"), it indeed terminates with [ 1049.684974] memory memory35: Offline failed. however, the dmesg doesn't indicate UEFI firmware (no EFI memmap, no references to EFI etc). To me it looks like a SeaBIOS VM. Should we correct the BZ Component? Thanks. In addition, "mem_test.log-20190210" contains no references to "pflash" or "OVMF" -- I'd expect those on the QEMU command line, for setting Component=edk2. Thanks. (In reply to Laszlo Ersek from comment #2) > Hi Liran, > > the BZ Component field is "edk2", but comment #0 says, "Create a VM(1GB > memory, 16 max memory), RHEL8 image, *BIOS*." (emphasis mine). > > Also, regarding "dmesg.log" from the attachment ("logs.tar.xz"), it indeed > terminates with > > [ 1049.684974] memory memory35: Offline failed. > > however, the dmesg doesn't indicate UEFI firmware (no EFI memmap, no > references to EFI etc). To me it looks like a SeaBIOS VM. Should we correct > the BZ Component? Thanks. Sure, moved to seabios. Thanks. It's first hot-unplug BZ in RHEL8, as far as I'm aware it is still impossible to unplug memory reliably upstream. There were some work done in that area (like removing time-outs and continue attempting to remove memory, which could improve likehood of removal and explains CPU load). RHEL8 is probably the same as RHEL7 in memory hot-unplug area (Baoquan He backported many fixes from upstream into RHEL7) Long story in relevant BZs from RHEL7 (probably should be cloned to RHEL8) Bug 1245892 - hot-unhotplug guest memory fail most of the time because it is in use Bug 1258312 When un-hotplug memory failed, libvirt gives user a wrong message Reassigning bug back to kernel and CCing people involved in fixing them. I agree with Igor. And we have bug 1654978 for rhel8. This one might be duplicate. Hi Igor, (In reply to Igor Mammedov from comment #7) > It's first hot-unplug BZ in RHEL8, as far as I'm aware it is still > impossible to unplug memory reliably upstream. > There were some work done in that area (like removing time-outs and continue > attempting to remove memory, which could improve likehood of removal and > explains CPU load). > > RHEL8 is probably the same as RHEL7 in memory hot-unplug area (Baoquan He > backported many fixes from upstream into RHEL7) RHEL8 probably is different than rhel7 on memory hotplug, at least on x86 64, we have got good test results. In rhel7, since virt team didn't apply necessary udev rule, the memory block may not be onlined as online_movable, that's necessary for memory hotplug in rhel7 because of a memory defect. So as far as I know, rhel8 has different status as rhel7. As for upstream kernel, it behaves very well on memory hotplug on x86_64. Seems there's regression issue on ppc platform which is under discussion in upstream. Thanks Baoquan Created attachment 1534440 [details]
RHEL8 qemu guest memory hotplug steps
Hello, Could you share the detailed step to reproduce? I tried to do memory hotplug on RHEL8 Qemu guest and it worked well. I attached the steps I ran in Comment 10. Before memory hot-remove: total used free shared buff/cache available Mem: 9048584 248312 8445376 8768 354896 8648988 Swap: 2097148 0 2097148 After memory hot-remove: total used free shared buff/cache available Mem: 8000008 246520 7398584 8768 354904 7643260 Swap: 2097148 0 2097148 Thanks, Masa Please refer to the comments: https://bugzilla.redhat.com/show_bug.cgi?id=1654978#c26 So I think this is not a bug, suggest close it as NOTABUG. Thanks Baoquan Per comment as below, I would like to close this bug as NOTABUG. https://bugzilla.redhat.com/show_bug.cgi?id=1654978#c23 Please reopen it if any concern is raised. Thanks Baoquan I'm re-opening this bug. I retested again, using RHEL7.6 hosts and RHEL8 guest (kernel-4.18.0-80.el8.x86_64) I hot-plugged 5 DIMMs, each of 256MB. When I try to unplug each DIMM I see on the guest VM: With balloon device on the VM: "Offlined pages 32768 memory memory38: Offline failed." Without balloon device on the VM: "memory memory38: Offline failed." On each DIMM it's another memory number. On RHV side, the operation is successful, but on the guest it's clearly not, the DIMM also stays in the VM devices tab. This looks like what Igor mentioned in comment #7. (In reply to Liran Rotenberg from comment #14) > I'm re-opening this bug. > > I retested again, using RHEL7.6 hosts and RHEL8 guest > (kernel-4.18.0-80.el8.x86_64) Hi Liran, did you add 'movable_node' in guest kernel line as suggested by Baoquan in bug1654978? Seems it works to me. Thanks. > I hot-plugged 5 DIMMs, each of 256MB. > When I try to unplug each DIMM I see on the guest VM: > > With balloon device on the VM: > "Offlined pages 32768 > memory memory38: Offline failed." > > Without balloon device on the VM: > "memory memory38: Offline failed." > > On each DIMM it's another memory number. > > On RHV side, the operation is successful, but on the guest it's clearly not, > the DIMM also stays in the VM devices tab. > > This looks like what Igor mentioned in comment #7. Hi Yumei, I just tested it with adding 'movable_node' in the guest kernel line. Solved the issue here. I'm moving this bug to documentation, if any user wish to use el8 guests. Thanks! Published as known issue in RHV 4.4.2 release notes. |