CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE is enabled on fedora s390 kernel config. This leads to autoonlining of standby memory on zvm during boottime.
Reproducible: Always
Steps to Reproduce:
1. s390 zvm configuration:
#cp define storage 12g standby 3g
2. boot the z/vm
3. Result:
* lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000003bfffffff 15G online yes 0-59
Memory block size: 256M
Total online memory: 15G
Total offline memory: 0B
4. grep -R "CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE" config-6.2.9-300.fc38.s390x
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
Actual Results:
* grep -R "CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE" config-6.2.9-300.fc38.s390x
CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
* lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000003bfffffff 15G online yes 0-59
Memory block size: 256M
Total online memory: 15G
Total offline memory: 0B
* Due to enablement of auto online feature, all the standby memory are
converted to online during boottime.
Expected Results:
* lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000002FFFFFFFF 12G online yes 0-47
0x0000000300000000-0x00000003BFFFFFFF 3G offline 48-59
Memory block size: 256M
Total online memory: 12G
Total offline memory: 3G
* Auto online feature should be disabled on s390x.
* The CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE config is already disabled on upstream s390 kernel defconfig, as this is recommended.
* Redhat fixes reference:
https://bugzilla.redhat.com/show_bug.cgi?id=1370161
* Redhat has disabled the autoonline feature:
grep -R "CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE" config-5.14.0*.el9.s390x
# CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE is not set