mm: remove superfluous __ClearPageActive()

To activate a page, mark_page_accessed() always holds a reference on it.
It either gets a new reference when adding a page to
lru_pvecs.activate_page or reuses an existing one it previously got when
it added a page to lru_pvecs.lru_add.  So it doesn't call SetPageActive()
on a page that doesn't have any reference left.  Therefore, the race is
impossible these days (I didn't brother to dig into its history).

For other paths, namely reclaim and migration, a reference count is always
held while calling SetPageActive() on a page.

SetPageSlabPfmemalloc() also uses SetPageActive(), but it's irrelevant to
LRU pages.

Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/20200818184704.3625199-2-yuzhao@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memremap.c b/mm/memremap.c
index 532ec3d36ab42ac14dacf0232b7428dfb2025719..7dc7aec971de891f81cc6f41ab1df39df8953d96 100644 (file)
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -494,8 +494,6 @@ void free_devmap_managed_page(struct page *page)
                return;
        }
 
-       /* Clear Active bit in case of parallel mark_page_accessed */
-       __ClearPageActive(page);
        __ClearPageWaiters(page);
 
        mem_cgroup_uncharge(page);

diff --git a/mm/swap.c b/mm/swap.c
index 82ddefda49043ee6a6a243041521be23b9077a7f..8c936404f254b401de75ac2208b1355abf39b848 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -943,8 +943,6 @@ void release_pages(struct page **pages, int nr)
                        del_page_from_lru_list(page, lruvec, page_off_lru(page));
                }
 
-               /* Clear Active bit in case of parallel mark_page_accessed */
-               __ClearPageActive(page);
                __ClearPageWaiters(page);
 
                list_add(&page->lru, &pages_to_free);