Re: [RFC 04/11] mm: remove SWAP_MLOCK check for SWAP_SUCCESS in ttu

Anshuman Khandual
2017-03-02T14:52:01Z

On 03/02/2017 12:09 PM, Minchan Kim wrote:
> If the page is mapped and rescue in ttuo, page_mapcount(page) == 0 cannot

Nit: "ttuo" is very cryptic. Please expand it.

> be true so page_mapcount check in ttu is enough to return SWAP_SUCCESS.
> IOW, SWAP_MLOCK check is redundant so remove it.

Right, page_mapcount(page) should be enough to tell whether swapping
out happened successfully or the page is still mapped in some page
table.

>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> mm/rmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 3a14013..0a48958 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1523,7 +1523,7 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
> else
> ret = rmap_walk(page, &rwc);
>
> - if (ret != SWAP_MLOCK && !page_mapcount(page))
> + if (!page_mapcount(page))
> ret = SWAP_SUCCESS;
> return ret;
> }