2020-09-02 14:27:49

by David Howells

Subject: [PATCH] Fix khugepaged's request size in collapse_file()

collapse_file() in khugepaged passes PAGE_SIZE as the number of pages to be
read ahead to page_cache_sync_readahead(). It seems this was expressed as a
number of bytes rather than a number of pages.

Fix it to use the number of pages to the end of the window instead.

Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: David Howells <[email protected]>
Acked-by: Song Liu <[email protected]>
Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
---

mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 6d199c353281..f2d243077b74 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1706,7 +1706,7 @@ static void collapse_file(struct mm_struct *mm,
xas_unlock_irq(&xas);
page_cache_sync_readahead(mapping, &file->f_ra,
file, index,
- PAGE_SIZE);
+ end - index);
/* drain pagevecs to help isolate_lru_page() */
lru_add_drain();
page = find_lock_page(mapping, index);

2020-09-02 18:55:57

by Pankaj Gupta

Subject: Re: [PATCH] Fix khugepaged's request size in collapse_file()

> collapse_file() in khugepaged passes PAGE_SIZE as the number of pages to be
> read ahead to page_cache_sync_readahead(). It seems this was expressed as a
> number of bytes rather than a number of pages.
>
> Fix it to use the number of pages to the end of the window instead.
>
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Signed-off-by: David Howells <[email protected]>
> Acked-by: Song Liu <[email protected]>
> Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
> ---
>
> mm/khugepaged.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 6d199c353281..f2d243077b74 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1706,7 +1706,7 @@ static void collapse_file(struct mm_struct *mm,
> xas_unlock_irq(&xas);
> page_cache_sync_readahead(mapping, &file->f_ra,
> file, index,
> - PAGE_SIZE);
> + end - index);
> /* drain pagevecs to help isolate_lru_page() */
> lru_add_drain();
> page = find_lock_page(mapping, index);
>

Acked-by: Pankaj Gupta <[email protected]>

2020-09-02 19:30:04

by Yang Shi

Subject: Re: [PATCH] Fix khugepaged's request size in collapse_file()

On Wed, Sep 2, 2020 at 7:16 AM David Howells <[email protected]> wrote:
>
> collapse_file() in khugepaged passes PAGE_SIZE as the number of pages to be
> read ahead to page_cache_sync_readahead(). It seems this was expressed as a
> number of bytes rather than a number of pages.
>
> Fix it to use the number of pages to the end of the window instead.
>
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Signed-off-by: David Howells <[email protected]>
> Acked-by: Song Liu <[email protected]>
> Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>

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

> ---
>
> mm/khugepaged.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 6d199c353281..f2d243077b74 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1706,7 +1706,7 @@ static void collapse_file(struct mm_struct *mm,
> xas_unlock_irq(&xas);
> page_cache_sync_readahead(mapping, &file->f_ra,
> file, index,
> - PAGE_SIZE);
> + end - index);
> /* drain pagevecs to help isolate_lru_page() */
> lru_add_drain();
> page = find_lock_page(mapping, index);
>
>
>