[PATCH v17 02/21] mm/page_idle: no unlikely double check for idle page counting

Alex Shi
2020-07-25T13:01:26Z

As func comments mentioned, few isolated page missing be tolerated.
So why not do further to drop the unlikely double check. That won't
cause more idle pages, but reduce a lock contention.

This is also a preparation for later new page isolation feature.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/page_idle.c | 8 --------
1 file changed, 8 deletions(-)

diff --git a/mm/page_idle.c b/mm/page_idle.c
index 057c61df12db..5fdd753e151a 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -32,19 +32,11 @@
static struct page *page_idle_get_page(unsigned long pfn)
{
struct page *page = pfn_to_online_page(pfn);
- pg_data_t *pgdat;

if (!page || !PageLRU(page) ||
!get_page_unless_zero(page))
return NULL;

- pgdat = page_pgdat(page);
- spin_lock_irq(&pgdat->lru_lock);
- if (unlikely(!PageLRU(page))) {
- put_page(page);
- page = NULL;
- }
- spin_unlock_irq(&pgdat->lru_lock);
return page;
}

--
1.8.3.1