linux-kernel - [PATCH v16 02/22] mm/page_idle: no unlikely double check for idle page counting

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Date:   Sat, 11 Jul 2020 08:58:36 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     akpm@...ux-foundation.org, mgorman@...hsingularity.net,
        tj@...nel.org, hughd@...gle.com, khlebnikov@...dex-team.ru,
        daniel.m.jordan@...cle.com, yang.shi@...ux.alibaba.com,
        willy@...radead.org, hannes@...xchg.org, lkp@...el.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org, shakeelb@...gle.com,
        iamjoonsoo.kim@....com, richard.weiyang@...il.com,
        kirill@...temov.name
Subject: [PATCH v16 02/22] mm/page_idle: no unlikely double check for idle page counting

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@...ux.alibaba.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.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