Bug 1370161

Summary:	s390x standby memory automatically onlined after boot
Product:	Red Hat Enterprise Linux 7	Reporter:	Milos Vyletel <milos>
Component:	systemd	Assignee:	systemd-maint
Status:	CLOSED ERRATA	QA Contact:	Branislav Blaškovič <bblaskov>
Severity:	high	Docs Contact:
Priority:	urgent
Version:	7.2	CC:	bblaskov, bugproxy, fkrska, fsumsal, hannsj_uhl, lnykryn, mkolaja, mrdest, msekleta, snagar, systemd-maint-list, tlavigne
Target Milestone:	rc	Keywords:	Regression, ZStream
Target Release:	7.3
Hardware:	s390x
OS:	Linux
Whiteboard:
Fixed In Version:	systemd-219-30.el7	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1375603 1381123 1381885 (view as bug list)		Environment:
Last Closed:	2016-11-04 00:56:12 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1230910, 1375603, 1381123, 1381885

Description Milos Vyletel 2016-08-25 12:16:56 UTC

Description of problem:
Starting with RHEL 7.2 standby memory on z/VM is automatically onlined whereas
it should stay offline until it is manually onlined later on when needed.

I've tracked this down to systemd BZ 1105020 that added udev rule to auto
online newly added memory. This works on some architectures but causes this
regression on z/VM where the hotplug memory is always present but only onlined
when needed. Relevant commit

https://github.com/lnykryn/systemd-rhel/commit/57adc4317ee2553d2d3ac84ef9625ed9c1cf5700

Version-Release number of selected component (if applicable):
systemd-219-19.el7_2.12.s390x

How reproducible:
always

Steps to Reproduce:
1. create z/VM with standby memory

USER XXXXX YYYYY 1G 2G GC
COMMAND DEFINE STORAGE 1G STANDBY 1G
COMMAND SET RUN ON

2. boot

Actual results:
[root@ibm-z-03 ~]# lsmem -a
Address Range                          Size (MB)  State    Removable  Device
===============================================================================
0x0000000000000000-0x000000000fffffff        256  online   no         0-127
0x0000000010000000-0x000000001fffffff        256  online   yes        128-255
0x0000000020000000-0x000000002fffffff        256  online   yes        256-383
0x0000000030000000-0x000000003fffffff        256  online   no         384-511
0x0000000040000000-0x000000004fffffff        256  online   no         512-639
0x0000000050000000-0x000000005fffffff        256  online   no         640-767
0x0000000060000000-0x000000006fffffff        256  online   no         768-895
0x0000000070000000-0x000000007fffffff        256  online   no         896-1023

Expected results:
[root@ibm-z-03 ~]# lsmem  -a
Address Range                          Size (MB)  State    Removable  Device
===============================================================================
0x0000000000000000-0x000000000fffffff        256  online   no         0-127
0x0000000010000000-0x000000001fffffff        256  online   yes        128-255
0x0000000020000000-0x000000002fffffff        256  online   yes        256-383
0x0000000030000000-0x000000003fffffff        256  online   no         384-511
0x0000000040000000-0x000000004fffffff        256  offline  -          512-639
0x0000000050000000-0x000000005fffffff        256  offline  -          640-767
0x0000000060000000-0x000000006fffffff        256  offline  -          768-895
0x0000000070000000-0x000000007fffffff        256  offline  -          896-1023

Additional info:

Comment 3 Michal Sekletar 2016-08-26 11:31:40 UTC

I guess we could make this udev rule conditional and skip it on z/VM systems. Can you please provide output of systemd-detect-virt from this machine?

Comment 4 Milos Vyletel 2016-08-26 11:35:28 UTC

sure

[root@ibm-z-03 ~]# systemd-detect-virt
zvm

Comment 6 Michal Sekletar 2016-08-26 14:19:38 UTC

I modified udev rule as follows,

SUBSYSTEM=="memory", ACTION=="add", PROGRAM="/usr/bin/systemd-detect-virt", RESULT!="zvm", ATTR{state}=="offline", ATTR{state}="online"

This rule was confirmed to work as expected by Milos.

Comment 9 Milos Vyletel 2016-09-13 10:29:50 UTC

Michal,

turns out this is not only z/VM problem as IBM reports. This is what we were told

"Rereading the Bugzilla, I found
that the problem description seems to be limited to z/VM environment.
Actually the problem occurs even in native LPAR."

I've asked for systemd-virt-detect output to see if we can simply tweak the
rule to this additional platform.

Milos

Comment 10 Lukáš Nykrýn 2016-09-13 12:02:37 UTC

fix merged to upstream staging branch ->
https://github.com/lnykryn/systemd-rhel/commit/ad9ec899fe24c4b74841a30f9233cee3bd7a3287
https://github.com/lnykryn/systemd-rhel/commit/195083a33b4204d513787e7f4b6c63f19a0fe1c7
-> post

Comment 22 errata-xmlrpc 2016-11-04 00:56:12 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-2216.html