[PATCH v17 07/21] mm/thp: remove code path which never got into

From: Alex Shi
Date: Sat Jul 25 2020 - 09:01:39 EST

split_huge_page() will never call on a page which isn't on lru list, so
this code never got a chance to run, and should not be run, to add tail
pages on a lru list which head page isn't there.

Although the bug was never triggered, it'better be removed for code

BTW, it looks better to have a WARN() set in the wrong path, but the
path will be changed in incoming new page isolation func. So just save
it now.

Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
mm/huge_memory.c | 10 ----------
1 file changed, 10 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b18f21da4dac..1fb4147ff854 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2357,16 +2357,6 @@ static void lru_add_page_tail(struct page *head, struct page *page_tail,
/* page reclaim is reclaiming a huge page */
list_add_tail(&page_tail->lru, list);
- } else {
- /*
- * Head page has not yet been counted, as an hpage,
- * so we must account for each subpage individually.
- *
- * Put page_tail on the list at the correct position
- * so they all end up in order.
- */
- add_page_to_lru_list_tail(page_tail, lruvec,
- page_lru(page_tail));