With memory hotplug, the removal of hot-plugged memory is also condition on there not being and "unmovable" memory pages within the memory region that you're trying to remove - with it returning an EBUSY error if it is not presently able to offline that region.
>From the memory-hotplug.txt in the kernel source: > 6.2. How to offline memory > ------------ > You can offline a section by using the same sysfs interface that was used in > memory onlining. > > % echo offline > /sys/devices/system/memory/memoryXXX/state > > If offline succeeds, the state of the memory section is changed to be > "offline". > If it fails, some error core (like -EBUSY) will be returned by the kernel. > Even if a section does not belong to ZONE_MOVABLE, you can try to offline it. > If it doesn't contain 'unmovable' memory, you'll get success. > > A section under ZONE_MOVABLE is considered to be able to be offlined easily. > But under some busy state, it may return -EBUSY. Even if a memory section > cannot be offlined due to -EBUSY, you can retry offlining it and may be able > to > offline it (or not). > (For example, a page is referred to by some kernel internal call and released > soon.) > > On Fri, Dec 6, 2013 at 9:41 PM, Michael MacIsaac <[email protected]> wrote: > Mike, > > Thanks for the quick reply. > > There are two other chunks online (0 and 1): > > # mzlsmemory -v zntc76 > zntc76: > Memory in user directory: > Default memory: 512M > Standby memory: 1G > Reserved memory: 0 > Maximum memory: 2G > > Memory block size: 256 MB > Memory device size: 2 MB > > Memory blocks in /sys/devices/system/memory: > Block Start State Removable > ----- ----- ----- --------- > 0 0 online 0 > 1 256 online 0 > 2 512 online 1 > 3 768 offline 0 > 4 1024 offline 0 > 5 1280 offline 0 > Active memory: 768 MB > Offline memory: 768 MB > Removable memory: 256 MB > > Also, I perform the same step on a SLES 11 SP3 system and the last chunk > marked removable does go offline. > > "Mike MacIsaac" <mikemac at-sign us.ibm.com> > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
