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Date: Sat, 7 Jul 2018 14:11:18 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: ying.huang@...el.com
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-mm <linux-mm@...ck.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Michal Hocko <mhocko@...e.com>,
Johannes Weiner <hannes@...xchg.org>,
Shaohua Li <shli@...nel.org>, hughd@...gle.com,
Minchan Kim <minchan@...nel.org>,
Rik van Riel <riel@...hat.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
n-horiguchi@...jp.nec.com, zi.yan@...rutgers.edu,
daniel.m.jordan@...cle.com
Subject: Re: [PATCH -mm -v4 01/21] mm, THP, swap: Enable PMD swap operations
for CONFIG_THP_SWAP
On Thu, Jun 21, 2018 at 8:55 PM Huang, Ying <ying.huang@...el.com> wrote:
>
> From: Huang Ying <ying.huang@...el.com>
>
> Previously, the PMD swap operations are only enabled for
> CONFIG_ARCH_ENABLE_THP_MIGRATION. Because they are only used by the
> THP migration support. We will support PMD swap mapping to the huge
> swap cluster and swapin the THP as a whole. That will be enabled via
> CONFIG_THP_SWAP and needs these PMD swap operations. So enable the
> PMD swap operations for CONFIG_THP_SWAP too.
>
> Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Shaohua Li <shli@...nel.org>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Cc: Zi Yan <zi.yan@...rutgers.edu>
> Cc: Daniel Jordan <daniel.m.jordan@...cle.com>
> ---
> arch/x86/include/asm/pgtable.h | 2 +-
> include/asm-generic/pgtable.h | 2 +-
> include/linux/swapops.h | 44 ++++++++++++++++++++++--------------------
> 3 files changed, 25 insertions(+), 23 deletions(-)
>
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 99ecde23c3ec..13bf58838daf 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1224,7 +1224,7 @@ static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
> return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY);
> }
>
> -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> +#if defined(CONFIG_ARCH_ENABLE_THP_MIGRATION) || defined(CONFIG_THP_SWAP)
How about introducing a new config symbol representing the common
infrastructure between the two and have them select that symbol.
Would that also allow us to clean up the usage of
CONFIG_ARCH_ENABLE_THP_MIGRATION in fs/proc/task_mmu.c? In other
words, what's the point of having nice ifdef'd alternatives in header
files when ifdefs are still showing up in C files, all of it should be
optionally determined by header files.
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