Re: [PATCH] mm/hugetlb: suppress wrong warning info when alloc gigantic page

[David Hildenbrand]

On 19.02.21 20:14, Mike Kravetz wrote:
> On 2/19/21 4:39 AM, Chen Wandun wrote:
> > If hugetlb_cma is enabled, it will skip boot time allocation
> > when allocating gigantic page, that doesn't means allocation
> > failure, so suppress this warning info.
>
> Normally the addition of warning messages is discouraged.  However, in
> this case the additional message provides value.  Why?
>
> Prior to the commit cf11e85fc08c, one could have a kernel command line
> that contains:
>
> hugepagesz=1G hugepages=16
>
> This would allocate 16 1G pages at boot time.
>
> After the commit, someone could specify a command line containing:
>
> hugepagesz=1G hugepages=16 hugetlb_cma=16G
>
> In this case, 16G of CMA will be reserved for 1G huge page allocations
> after boot time.  The parameter 'hugepages=16' is ignored, and the warning
> message is logged.  The warning message should only be logged when the
> kernel parameter 'hugepages=' is ignored.
>
> IMO, it make sense to log a warning if ignoring a user specified parameter.
> The user should not be attempting boot time allocation and CMA reservation
> for 1G pages.
>
> I do not think we should drop the warning as the it tells the user thay
> have specified two incompatible allocation options.

I agree. It has value.

--
Thanks,

David / dhildenb