linux-kernel - Re: [PATCH v1 0/9] s390: implement and optimize vmemmap

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Date:   Fri, 10 Jul 2020 15:57:09 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-mm@...ck.org, Christian Borntraeger <borntraeger@...ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH v1 0/9] s390: implement and optimize vmemmap_free()

On Wed, Jul 08, 2020 at 02:16:39PM +0200, David Hildenbrand wrote:
> >>> Hmm.. I really would like to see if there would be only a single page
> >>> table walker left in vmem.c, which handles both adding and removing
> >>> things.
> >>> Now we end up with two different page table walk implementations
> >>> within the same file. However not sure if it is worth the effort to
> >>> unify them though.
> >>
> >> I tried to unify vmemmap_populate() and vmem_add_range() already and
> >> didn't like the end result ... so, unifying these along with the removal
> >> part won't be any better - most probably. Open for suggestions :)
> >>
> >> (at least arm64 and x86-64 handle it similarly)
> >>
> > 
> > I'll play with something like
> > 
> > static void modify_pagetable(unsigned long start, unsigned long end,
> > 			     bool direct, bool add)
> > 
> > and see how it turns out.
> > 
> 
> Did a quick hack. With a single walker (modify_pagetable) I get
> 
>  arch/s390/mm/vmem.c | 628 ++++++++++++++++++++++++++++++--------------
>  1 file changed, 434 insertions(+), 194 deletions(-)
> 
> Overall looks cleaner, only modify_pte_table() and modify_pmd_table()
> are a little more involved ...

Would you mind to resend the series with this integrated?