On Fri, Oct 30, 2015 at 01:47:11PM +0100, Michal Hocko wrote:
On Fri 30-10-15 16:01:42, Minchan Kim wrote:
quoted
deactivate_page aims for accelerate for reclaiming through
moving pages from active list to inactive list so we should
clear PG_referenced for the goal.
I might be missing something but aren't we using PG_referenced only for
pagecache (and shmem) pages?
You don't miss anything. For pages which are candidate of MADV_FREEing(
ie, normal anonymous page, not shmem, tmpfs), they shouldn't have any
PG_referenced. Although normal anonymous pages have it, VM doesn't respect
it. One thing I suspect is GUP with FOLL_TOUCH which calls mark_page_accesssed
on anonymous page and will mark PG_referenced.
Technically, it's not a problem but just want to notice in this time.
Primary reason was I want to make deactivate_page *general* so it could
be used for file page as well as anon pages in future.
But at the moment, user of deactivate_page is only MADV_FREE so it might
be better to merge the logic for anon page deactivation into
deactivate_file_page and rename it as general "deactivate_page"
if you're thinking it's better.
quoted
Acked-by: Hugh Dickins <hughd@google.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/swap.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/swap.c b/mm/swap.c
index d0eacc5f62a3..4a6aec976ab1 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -810,6 +810,7 @@ static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
ClearPageActive(page);
+ ClearPageReferenced(page);
add_page_to_lru_list(page, lruvec, lru);
__count_vm_event(PGDEACTIVATE);
--
1.9.1
--
Michal Hocko
SUSE Labs
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