Messages in this thread |  | | Subject | Re: [PATCH v3] mm/hotplug: Only respect mem= parameter during boot stage | From | Jürgen Groß <> | Date | Tue, 4 Feb 2020 08:53:30 +0100 |
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On 04.02.20 06:06, Baoquan He wrote: > In commit 357b4da50a62 ("x86: respect memory size limiting via mem= > parameter") a global varialbe max_mem_size is added to store > the value parsed from 'mem= ', then checked when memory region is > added. This truly stops those DIMMs from being added into system memory > during boot-time. > > However, it also limits the later memory hotplug functionality. Any > DIMM can't be hotplugged any more if its region is beyond the > max_mem_size. We will get errors like: > > [ 216.387164] acpi PNP0C80:02: add_memory failed > [ 216.389301] acpi PNP0C80:02: acpi_memory_enable_device() error > [ 216.392187] acpi PNP0C80:02: Enumeration failure > > This will cause issue in a known use case where 'mem=' is added to > the hypervisor. The memory that lies after 'mem=' boundary will be > assigned to KVM guests. After commit 357b4da50a62 merged, memory > can't be extended dynamically if system memory on hypervisor is not > sufficient. > > So fix it by also checking if it's during boot-time restricting to add > memory. Otherwise, skip the restriction. > > And also add this use case to document of 'mem=' kernel parameter. > > Fixes: 357b4da50a62 ("x86: respect memory size limiting via mem= parameter") > Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
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