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

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Date:   Thu, 5 Oct 2023 20:08:36 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        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 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.
-- 
Mike Kravetz