Re: [PATCH] hugetlb: Add nohugepages parameter to prevent hugepages creation

[Mike Kravetz]

On 10/15/19 7:09 AM, Guilherme G. Piccoli wrote:
> 
> 
> On 10/15/19 11:05 AM, Michal Hocko wrote:
>> On Tue 15-10-19 10:58:36, Guilherme G. Piccoli wrote:
>>> On 10/15/19 9:18 AM, Michal Hocko wrote:
>>>> I do agree with Qian Cai here. Kdump kernel requires a very tailored
>>>> environment considering it is running in a very restricted
>>>> configuration. The hugetlb pre-allocation sounds like a tooling problem
>>>> and should be fixed at that layer.
>>>>
>>>
>>> Hi Michal, thanks for your response. Can you suggest me a current way of
>>> preventing hugepages for being created, using userspace? The goal for this
>>> patch is exactly this, introduce such a way.
>>
>> Simply restrict the environment to not allocate any hugepages? Kdump
>> already controls the kernel command line and it also starts only a very
>> minimal subset of services. So who is allocating those hugepages?
>> sysctls should be already excluded by default as Qian mentioned.
>>
> 
> 
> OK, thanks Michal and Qian, I'll try to make things work from kdump perspective. The trick part is exactly preventing the sysctl to get applied heh
> 

Please do let us know if this can be done in tooling.

I am not opposed to the approach taken in your v2 patch as it essentially
uses the hugepages_supported() functionality that exists today.  However,
it seems that other distros have ways around this issue.  As such, I would
prefer if the issue was addressed in the tooling.
-- 
Mike Kravetz