...of course, the same file says that the removable flag in sysfs should
only be one when every memory segment in the block is removable, so it's
possible this is a bug in the reporting of the removability of that memory.


On Fri, Dec 6, 2013 at 10:24 PM, Christian Paro <[email protected]>wrote:

> 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>
>>
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>
>

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