linux-kernel - Re: [PATCH 2/3] mm: add mm_pxd_folded checks to pgtable

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Message-ID: <20181031090439.5uhyk74g2e3j6lm3@kshutemo-mobl1>
Date:   Wed, 31 Oct 2018 12:04:39 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:     Li Wang <liwang@...hat.com>, Guenter Roeck <linux@...ck-us.net>,
        Janosch Frank <frankja@...ux.vnet.ibm.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH 2/3] mm: add mm_pxd_folded checks to pgtable_bytes
 accounting functions

On Mon, Oct 15, 2018 at 06:42:38PM +0200, Martin Schwidefsky wrote:
> The common mm code calls mm_dec_nr_pmds() and mm_dec_nr_puds()
> in free_pgtables() if the address range spans a full pud or pmd.
> If mm_dec_nr_puds/mm_dec_nr_pmds are non-empty due to configuration
> settings they blindly subtract the size of the pmd or pud table from
> pgtable_bytes even if the pud or pmd page table layer is folded.
> 
> Add explicit mm_[pmd|pud]_folded checks to the four pgtable_bytes
> accounting functions mm_inc_nr_puds, mm_inc_nr_pmds, mm_dec_nr_puds
> and mm_dec_nr_pmds. As the check for folded page tables can be
> overwritten by the architecture, this allows to keep a correct
> pgtable_bytes value for platforms that use a dynamic number of
> page table levels.
> 
> Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>

Looks fine to me.

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov