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From:   Alex Shi <alex.shi@linux.alibaba.com>
To:     akpm@linux-foundation.org, mgorman@techsingularity.net,
        tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
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Cc:     Alex Shi <alex.shi@linux.alibaba.com>
Subject: [PATCH v15 02/21] mm/page_idle: no unlikely double check for idle page counting
Date:   Tue,  7 Jul 2020 19:46:34 +0800
Message-Id: <1594122412-28057-3-git-send-email-alex.shi@linux.alibaba.com>
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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