linux-kernel - Re: [PATCH v4 8/8] hugetlb: batch TLB flushes when restoring vmemmap

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Message-ID: <20230919215351.GD425719@monkey>
Date:   Tue, 19 Sep 2023 14:53:51 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Muchun Song <muchun.song@...ux.dev>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>,
        Joao Martins <joao.m.martins@...cle.com>,
        Oscar Salvador <osalvador@...e.de>,
        David Hildenbrand <david@...hat.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        David Rientjes <rientjes@...gle.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Naoya Horiguchi <naoya.horiguchi@...ux.dev>,
        Barry Song <21cnbao@...il.com>, Michal Hocko <mhocko@...e.com>,
        Matthew Wilcox <willy@...radead.org>,
        Xiongchun Duan <duanxiongchun@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v4 8/8] hugetlb: batch TLB flushes when restoring vmemmap

On 09/19/23 14:48, Muchun Song wrote:
> 
> 
> On 2023/9/19 07:02, Mike Kravetz wrote:
> > Update the internal hugetlb restore vmemmap code path such that TLB
> > flushing can be batched.  Use the existing mechanism of passing the
> > VMEMMAP_REMAP_NO_TLB_FLUSH flag to indicate flushing should not be
> > performed for individual pages.  The routine hugetlb_vmemmap_restore_folios
> > is the only user of this new mechanism, and it will perform a global
> > flush after all vmemmap is restored.
> > 
> > Signed-off-by: Joao Martins <joao.m.martins@...cle.com>
> > Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
> > ---
> >   mm/hugetlb_vmemmap.c | 39 ++++++++++++++++++++++++---------------
> >   1 file changed, 24 insertions(+), 15 deletions(-)
> > 
> > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> > index a6c356acb1fc..ae2229f19158 100644
> > --- a/mm/hugetlb_vmemmap.c
> > +++ b/mm/hugetlb_vmemmap.c
> > @@ -460,18 +460,19 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
> >    * @end:	end address of the vmemmap virtual address range that we want to
> >    *		remap.
> >    * @reuse:	reuse address.
> > + * @flags:	modify behavior for bulk operations
> 
> Please keep the comment consistent with vmemmap_remap_split(), which says:
> "@flags:    modifications to vmemmap_remap_walk flags".

Thanks, will change in next version.
-- 
Mike Kravetz