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

Only some nits:

s/varialbe global/variable/

> the value parsed from 'mem= ', then checked when memory region is
> added. This truly stops those DIMM from being added into system memory
s/DIMM/DIMMs/

> 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

s/memory board/DIMM/ ?

s/hot added/hotplugged/ ?

> max_mem_size. System will print error like below:

"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
>
> From document of 'mem= ' parameter, it should be a restriction during

"the documentation of the"

> boot, but not impact the system memory adding/removing after booting.

"but not impact memory hotplug once booted."

>
> 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

s/when restrict memory adding/restricting to add memory/

> adding. Otherwise, skip the restriction.
>
> Fixes: 357b4da50a62 ("x86: respect memory size limiting via mem= parameter")
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> mm/memory_hotplug.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 55ac23ef11c1..989707295d15 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -105,7 +105,11 @@ static struct resource *register_memory_resource(u64 start, u64 size)
> unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> char *resource_name = "System RAM";
>
> - if (start + size > max_mem_size)
> + /*
> + * Make sure value parsed from 'mem=' only restricts memory adding
> + * during boot-time, so that memory hotplug won't be impacted.

s/during boot-time/while booting/

Only some nits, thanks!

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb

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