Re: [Patch v2] mm/hotplug: Only respect mem= parameter during boot stage

[JÃrgen GroÃ]

On 10.12.19 09:44, Baoquan He wrote:
> In commit 357b4da50a62 ("x86: respect memory size limiting via mem=
> parameter") a global varialbe global max_mem_size is added to store
> the value parsed from 'mem= ', then checked when memory region is
> added. This truly stops those DIMM from being added into system memory
> during boot-time.
>
> However, it also limits the later memory hotplug functionality. Any
> memory board can't be hot added any more if its region is beyond the
> max_mem_size. System will print error like below:
>
> [  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
>
>  From document of 'mem= ' parameter, it should be a restriction during
> boot, but not impact the system memory adding/removing after booting.
>
>    mem=nn[KMG]     [KNL,BOOT] Force usage of a specific amount of memory
> 	          ...
>
> So fix it by also checking if it's during boot-time when restrict memory
> adding. Otherwise, skip the restriction.
>
> Fixes: 357b4da50a62 ("x86: respect memory size limiting via mem= parameter")
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen