linux-kernel - Re: [PATCH v6 2/8] hugetlb: restructure pool allocations

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Message-ID: <070bd916-d4d6-41c2-9f51-af35e80c96b9@linaro.org>
Date:   Mon, 9 Oct 2023 12:11:42 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Mike Kravetz <mike.kravetz@...cle.com>,
        Anshuman Khandual <anshuman.khandual@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Xiongchun Duan <duanxiongchun@...edance.com>,
        Barry Song <21cnbao@...il.com>,
        David Rientjes <rientjes@...gle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        Naoya Horiguchi <naoya.horiguchi@...ux.dev>,
        Joao Martins <joao.m.martins@...cle.com>,
        David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Oscar Salvador <osalvador@...e.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/8] hugetlb: restructure pool allocations

On 9.10.2023 05:29, Mike Kravetz wrote:
> On 10/06/23 15:35, Mike Kravetz wrote:
>> On 10/06/23 23:39, Konrad Dybcio wrote:
>>> On 6.10.2023 05:08, Mike Kravetz wrote:
>>>> On 10/02/23 11:57, Konrad Dybcio wrote:
>>>>>
>>>>>
>>>>> On 9/29/23 22:57, Mike Kravetz wrote:
>>>>>> On 09/27/23 13:26, Konrad Dybcio wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 26.09.2023 01:48, Mike Kravetz wrote:
>>>>>>>> Allocation of a hugetlb page for the hugetlb pool is done by the routine
>>>>>>>> alloc_pool_huge_page.  This routine will allocate contiguous pages from
>>>>>>>> a low level allocator, prep the pages for usage as a hugetlb page and
>>>>>>>> then add the resulting hugetlb page to the pool.
>>>>>>>>
>>>>>>>> In the 'prep' stage, optional vmemmap optimization is done.  For
>>>>>>>> performance reasons we want to perform vmemmap optimization on multiple
>>>>>>>> hugetlb pages at once.  To do this, restructure the hugetlb pool
>>>>>>>> allocation code such that vmemmap optimization can be isolated and later
>>>>>>>> batched.
>>>>>>>>
>>>>>>>> The code to allocate hugetlb pages from bootmem was also modified to
>>>>>>>> allow batching.
>>>>>>>>
>>>>>>>> No functional changes, only code restructure.
>>>>>>>>
>>>>>>>> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
>>>>>>>> Reviewed-by: Muchun Song <songmuchun@...edance.com>
>>>>>>>> ---
>>>>>>> Hi, looks like this patch prevents today's next from booting
>>>>>>> on at least one Qualcomm ARM64 platform. Reverting it makes
>>>>>>> the device boot again.
>>>>>>
>>>>>> Can you share the config used and any other specific information such as
>>>>>> kernel command line.
>>>>> Later this week.
>>>>
>>>> As mentioned, I have been unable to reproduce on arm64 platforms I can
>>>> access.  I have tried various config and boot options.  While doing so,
>>>> I came across one issue impacting kernels compiled without
>>>> CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP defined.  This is not something
>>>> that would prevent booting.
>>>>
>>>> I will send out an updated version series in the hope that any other
>>>> issues may be discovered.
>>> I'm pushing the "later this week" by answering near end of calendar
>>> day, Friday, but it seems like this patch in v7 still prevents the
>>> device from booting..
>>>
>>> You can find my defconfig at the link below.
>>>
>>> https://gist.github.com/konradybcio/d865f8dc9b12a98ba3875ec5a9aac42e
>>>
>>
>> Thanks!
>>
>> I assume there is no further information such as any console output?
>> Did any of you other arm64 platforms have this issue?
>>
>> Just trying to get as much information as possible to get to root cause.
> 
> I have not had success isolating the issue with your config file.
> 
> Since the only code changes in this patch deal with allocating hugetlb
> pages, I assume this is what you are doing?  Can you let me know how you
> are performing the allocations?  I assume it is on the kernel command
> line as these would be processed earliest in boot.
> 
> If you are not allocating hugetlb pages, then I need to think of what
> else may be happening.
> 
> Anshuman, any chance you (or someone else with access to arm64 platforms)
> could throw this on any platforms you have access to for a quick test?
I managed to get a boot log:

https://pastebin.com/GwurpCw9

This is using arch/arm64/boot/dts/qcom/sm8550-mtp.dts for reference

Konrad