On 11.03.20 15:26, Wei Yang wrote:
> On Wed, Mar 11, 2020 at 01:30:26PM +0100, David Hildenbrand wrote:
>> For now, distributions implement advanced udev rules to essentially
>> - Don't online any hotplugged memory (s390x)
>> - Online all memory to ZONE_NORMAL (e.g., most virt environments like
>>  hyperv)
>> - Online all memory to ZONE_MOVABLE in case the zone imbalance is taken
>>  care of (e.g., bare metal, special virt environments)
>>
>> In summary: All memory is usually onlined the same way, however, the
>> kernel always has to ask userspace to come up with the same answer.
>> E.g., HyperV always waits for a memory block to get onlined before
>> continuing, otherwise it might end up adding memory faster than
>> hotplugging it, which can result in strange OOM situations.
>>
>> Let's allow to specify a default online_type, not just "online" and
>> "offline". This allows distributions to configure the default online_type
>> when booting up and be done with it.
>>
>> We can now specify "offline", "online", "online_movable" and
>> "online_kernel" via
>> - "memhp_default_state=" on the kernel cmdline
>> - /sys/devices/systemn/memory/auto_online_blocks
>> just like we are able to specify for a single memory block via
>> /sys/devices/systemn/memory/memoryX/state
>>
>> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
>> Cc: Andrew Morton <a...@linux-foundation.org>
>> Cc: Michal Hocko <mho...@kernel.org>
>> Cc: Oscar Salvador <osalva...@suse.de>
>> Cc: "Rafael J. Wysocki" <raf...@kernel.org>
>> Cc: Baoquan He <b...@redhat.com>
>> Cc: Wei Yang <richard.weiy...@gmail.com>
>> Signed-off-by: David Hildenbrand <da...@redhat.com>
> 
> Ok, I got the reason to leave the change on string compare here.

Thanks for your *very fast* review! :)


-- 
Thanks,

David / dhildenb

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