linux-kernel - Re: [PATCH v2 10/10] mm: hwpoison_user_mappings() try_to_unmap() with TTU

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Message-ID: <20210610073833.GA1196948@hori.linux.bs1.fc.nec.co.jp>
Date:   Thu, 10 Jun 2021 07:38:35 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Hugh Dickins <hughd@...gle.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Wang Yugui <wangyugui@...-tech.com>,
        Matthew Wilcox <willy@...radead.org>,
        Alistair Popple <apopple@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>, Zi Yan <ziy@...dia.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Minchan Kim <minchan@...nel.org>, Jue Wang <juew@...gle.com>,
        Peter Xu <peterx@...hat.com>, Jan Kara <jack@...e.cz>,
        Shakeel Butt <shakeelb@...gle.com>,
        Oscar Salvador <osalvador@...e.de>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 10/10] mm: hwpoison_user_mappings() try_to_unmap() with
 TTU_SYNC

On Tue, Jun 08, 2021 at 09:30:00PM -0700, Hugh Dickins wrote:
> TTU_SYNC prevents an unlikely race, when try_to_unmap() returns shortly
> before the page is accounted as unmapped.  It is unlikely to coincide
> with hwpoisoning, but now that we have the flag, hwpoison_user_mappings()
> would do well to use it.
>
> Signed-off-by: Hugh Dickins <hughd@...gle.com>
> ---
> Patch added since the v1 series was posted.
>
>  mm/memory-failure.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index b6806e446567..e16edefca523 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1060,7 +1060,7 @@ static int get_hwpoison_page(struct page *p, unsigned long flags,
>  static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
>  				  int flags, struct page **hpagep)
>  {
> -	enum ttu_flags ttu = TTU_IGNORE_MLOCK;
> +	enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_SYNC;

Thanks for improving thp code.

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>