2020-04-14 11:09:53

by Kirill A. Shutemov

Subject: [PATCHv3, RESEND 4/8] khugepaged: Drain LRU add pagevec after swapin

__collapse_huge_page_isolate() may fail due to extra pin in the LRU add
pagevec. It's pretty common for swapin case: we swap in pages just to
fail due to the extra pin.

Drain LRU add pagevec on successful swapin.

Signed-off-by: Kirill A. Shutemov <[email protected]>
---
mm/khugepaged.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ee66c140c2d6..e3e41c2768d8 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -934,6 +934,11 @@ 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

2020-04-16 01:06:19

by Yang Shi

Subject: Re: [PATCHv3, RESEND 4/8] khugepaged: Drain LRU add pagevec after swapin

On 4/13/20 5:52 AM, Kirill A. Shutemov wrote:
> __collapse_huge_page_isolate() may fail due to extra pin in the LRU add
> pagevec. It's pretty common for swapin case: we swap in pages just to
> fail due to the extra pin.
>
> Drain LRU add pagevec on successful swapin.
>
> Signed-off-by: Kirill A. Shutemov <[email protected]>
> ---
> mm/khugepaged.c | 5 +++++
> 1 file changed, 5 insertions(+)

Acked-by: Yang Shi <[email protected]>

>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index ee66c140c2d6..e3e41c2768d8 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -934,6 +934,11 @@ 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;
> }