Re: [PATCHv2 4/8] khugepaged: Drain LRU add pagevec after swapin

From: Zi Yan <ziy@nvidia.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: <akpm@linux-foundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	"Yang Shi" <yang.shi@linux.alibaba.com>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCHv2 4/8] khugepaged: Drain LRU add pagevec after swapin
Date: Mon, 6 Apr 2020 09:11:27 -0400	[thread overview]
Message-ID: <592329FA-69D0-4801-A5DF-F9CC8A3FE305@nvidia.com> (raw)
In-Reply-To: <20200403112928.19742-5-kirill.shutemov@linux.intel.com>

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On 3 Apr 2020, at 7:29, Kirill A. Shutemov wrote:

> External email: Use caution opening links or attachments
>
>
> __collapse_huge_page_isolate() may fail due to extra pin in the LRU add
> pagevec. It's petty common for swapin case: we swap in pages just to

s/petty/pretty

> fail due to the extra pin.
>
> Drain LRU add pagevec on sucessfull swapin.

s/sucessfull/successful

>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
>  mm/khugepaged.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index fdc10ffde1ca..57ff287caf6b 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -940,6 +940,11 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm,
>         }
>         vmf.pte--;
>         pte_unmap(vmf.pte);
> +
> +       /* Drain LRU add pagevec to remove extra pin on the swapped in pages */
> +       if (swapped_in)
> +               lru_add_drain();
> +
>         trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1);
>         return true;
>  }
> --
> 2.26.0


—
Best Regards,
Yan Zi

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