Alert: Control Domain Memory Usage

Danp

@delaf I ran into the same thing recently. See solution below --

https://xcp-ng.org/forum/post/33291

delaf

@stormi I have a server with only search extra built-in weak-updates override updates. We will see if it is better.

delaf

@danp Thank you. I have downgraded one server.

@stormi So i have :

one server with 4.19.19-6.0.10.1.xcpng8.1
one server with kmemleak kernel
one server with search extra built-in weak-updates override updates

delaf

@stormi @r1
Four days later, I get:

one server (266) with alt-kernel: still no problem
one server (268) with 4.19.19-6.0.10.1.xcpng8.1: no more problem!
one server (272) with kmemleak kernel: no memleak detected, but the problem is present
one server (273) with search extra built-in weak-updates override updates: problem still present

stormi

@delaf Excellent news, especially if you can replicate on another host to be sure.

This thread is older than kernel-4.19.19-6.0.10.1.xcpng8.1 (especially in @dave's case), but it wouldn't be unlikely that several distinct memory leak causes exist.

r1

@delaf said in Alert: Control Domain Memory Usage:

one server (268) with 4.19.19-6.0.10.1.xcpng8.1: no more problem!

Yeah, we need to be sure that this is a stable kernel and somewhere after this, the memory leak seems to have introduced.

dave

I currently have:

top - 13:35:31 up 59 days, 17:11,  1 user,  load average: 0.43, 0.36, 0.34
Tasks: 646 total,   1 running, 436 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.8 us,  1.1 sy,  0.0 ni, 97.5 id,  0.3 wa,  0.0 hi,  0.1 si,  0.2 st
KiB Mem : 12205936 total,   149152 free, 10627080 used,  1429704 buff/cache
KiB Swap:  1048572 total,  1048572 free,        0 used.  1153360 avail Mem

top - 13:35:54 up 35 days, 17:29,  1 user,  load average: 0.54, 0.73, 0.77
Tasks: 489 total,   1 running, 324 sleeping,   0 stopped,   0 zombie
%Cpu(s):  3.5 us,  3.4 sy,  0.0 ni, 92.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.4 st
KiB Mem : 12207996 total,   155084 free,  9388032 used,  2664880 buff/cache
KiB Swap:  1048572 total,  1048572 free,        0 used.  2394220 avail Mem

both with:

# uname -a
Linux xs01 4.19.0+1 #1 SMP Thu Jun 11 16:18:33 CEST 2020 x86_64 x86_64 x86_64 GNU/Linux
# yum list installed | grep kernel
kernel.x86_64                   4.19.19-6.0.11.1.xcpng8.1   @xcp-ng-updates

shall i test something?

umbradark

I have a set of hosts on kernel-4.19.19-6.0.11.1.xcpng8.1 and I believe I'm hitting this as well. The OOM seems to kill openvswitch, which takes the host offline and in most cases, the VMs as well.

stormi

So, the difference between 4.19.19-6.0.10.1.xcpng8.1 and 4.19.19-6.0.11.1.xcpng8.1 is two patches meant to reduce the performance overhead of the CROSSTalk vulnerability mitigations.

So, assuming from @delaf's test results that one of those patches introduced the memory leak, I have built

Now here are the tests that you can do:

Reproduce @delaf's findings by running kernel-4.19.19-6.0.10.1.xcpng8.1: no more memory leaks?
Test this kernel I built with patch 53 disabled: https://nextcloud.vates.fr/index.php/s/YXWCSEwo8SWkfAZ
Test this kernel I built with patch 62 disabled: https://nextcloud.vates.fr/index.php/s/arj5YfdrkjMKbBy

If one of the patches is the cause of the memory leak, then one of the last two should still cause a memory leak and the other one not.

delaf

@stormi I have installed the two kernels

272 ~]# yum list installed kernel | grep kernel
kernel.x86_64                   4.19.19-6.0.11.1.0.1.patch53disabled.xcpng8.1

273 ~]# yum list installed kernel | grep kernel
kernel.x86_64                   4.19.19-6.0.11.1.0.1.patch62disabled.xcpng8.1

I have removed the modification in /etc/modprobe.d/dist.conf on server 273.

We have to wait a little bit now

stormi

FYI, the kernel with kmemleak support did detect something for a user who has a support ticket related to dom0 memory usage.

delaf

@stormi For the kernel-4.19.19-6.0.10.1.xcpng8.1 test, i'm not sure it solve the problem because I get a small memory increase. We have to wait a bit more

delaf

@stormi

server 266 with alt-kernel: still no problem.
server 268 with 4.19.19-6.0.10.1.xcpng8.1: the problem has begun some days ago after some stable days.
server 272 with 4.19.19-6.0.11.1.0.1.patch53disabled.xcpng8.1:
)
server 273 with 4.19.19-6.0.11.1.0.1.patch62disabled.xcpng8.1:

It seems that 4.19.19-6.0.11.1.0.1.patch62disabled.xcpng8.1 is more stable than 4.19.19-6.0.11.1.0.1.patch53disabled.xcpng8.1. But it is a but early to be sure.

delaf

@stormi @r1 server 273 with 4.19.19-6.0.11.1.0.1.patch62disabled.xcpng8.1 is still stable and 272 has the memory problem.

272
273

stormi

Thanks. It looks like I'm doomed to see seemingly contradictory results for every kernel-related issue (this one, and an other one regarding network performance): you don't have any leaks without patch 62, but you had leaks with kernel 4.19.19-6.0.10.1.xcpng8.1 which doesn't have that patch either. So it's hard to conclude anything

rblvlvl

Hey Guys,

we are facing the same issue with xcp 8.1.
We can't figure out what uses all this memory (8GB) or how to reduce it. Restarting the Toolstack did nothing and we can't afford a downtime because everything runs in production. Similar systems with same configurations don't show such a behavior.

I can provide you with some output from our system, maybe you can see something or help us finding a solution.

free -m

              total        used        free      shared  buff/cache   available
Mem:           7912        7595          82          33         234          62
Swap:          1023         216         807

xl top

      NAME  STATE   CPU(sec) CPU(%)     MEM(k) MEM(%)  MAXMEM(k) MAXMEM(%) VCPUS NETS NETTX(k) NETRX(k) VBDS   VBD_OO    VBD_RD     VBD_WR   VBD_RSECT   VBD_WSECT SSID
  Domain-0 -----r    7308446   52.1    8388608    3.1    8388608       3.1    16    0        0        0    0        0         0          0           0           0    0

xe vm-param-list uuid | grep memory

                         memory-actual ( RO): 8589934592
                         memory-target ( RO): <unknown>
                       memory-overhead ( RO): 84934656
                     memory-static-max ( RW): 8589934592
                    memory-dynamic-max ( RW): 8589934592
                    memory-dynamic-min ( RW): 8589934592
                     memory-static-min ( RW): 8589934592
                                memory (MRO): <not in database>

lsmod and grub.cfg
lsmod.txt
grub-cgf.txt

top output
Bildschirmfoto 2020-12-30 um 08.55.32.png

Tell me if you need more information or if you have any idea. Thanks.

olivierlambert

We need more details on the host.

Hardware detail (NICs, server model)
If all your hardware is fully BIOS/firmware up to date
The kind of storage used (iSCSI, FCoE, NFS?)

So far, we couldn't find a real common thing between people, and that's make hard to find the root cause.

rblvlvl

@olivierlambert

It is a Dell PowerEdge R440 Version 2.6.3 with an LACP Bond and we use an NFS Storage.

olivierlambert

That doesn't answer all my questions

rblvlvl

@olivierlambert

NIC:
Intel(R) Ethernet 10G 2P X550-t Adapter

driver: ixgbe
version: 5.5.2
firmware-version: 0x80000f32, 19.5.12

RAID Controller:

Product Name    : PERC H740P Adapter 
Serial No       : 04B00V9
FW Package Build: 50.9.4-3025

                    Mfg. Data
                ================
Mfg. Date       : 04/18/20
Rework Date     : 04/18/20
Revision No     : A03
Battery FRU     : N/A

                Image Versions in Flash:
                ================
Boot Block Version : 7.02.00.00-0021
BIOS Version       : 7.09.02.1_0x07090301
FW Version         : 5.093.00-2856
NVDATA Version     : 5.0900.06-0034

I know our hardware is not fully up to date, but for an update we need a timeframe, which can not be arranged that quickly.
Maybe someone knows a temporary fix to reduce the usage of the dom0 memory until the updates can be made.