Re: [PATCH] Documentation: hugetlb: Update hugetlb options

[Mike Kravetz <mike.kravetz@oracle.com>]

On 4/9/20 2:58 PM, Peter Xu wrote:
> The hugepage options are not documented clearly.
> 
> Firstly, default_hugepagesz= should always be specified after the
> declaration of the same type of huge page using hugepagesz=.  For
> example, if we boot a x86_64 system with kernel cmdline
> "default_hugepagesz=2M", we'll get a very funny error message:
> 
> "HugeTLB: unsupported default_hugepagesz 2097152. Reverting to 2097152"
> 
> It's understandable from code-wise because when hugetlb_init() we
> didn't have the 2M page hstate registered, so it's unsupported.
> However 2M is actually the default huge page size on x86_64, so we'll
> register it right after the error message.  However it's very
> confusing if without these knowledges.
> 
> Secondly, hugepages= option must be used _after_ another hugepagesz=.
> The word "interleave" is fine but it didn't declare the fact that
> each of the hugepages= option will be applied to the previous parsed
> hugepagesz= option.
> 
> State all these clear.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

Hi Peter,

Did you happen to see this patch series?

https://lore.kernel.org/linux-mm/20200401183819.20647-1-mike.kravetz@oracle.com/

That should address the documentation issue and more.
-- 
Mike Kravetz