linux-kernel - [PATCH v9 03/20] mm/page_idle: no unlikely double check for idle page counting

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Message-Id: <1583146830-169516-4-git-send-email-alex.shi@linux.alibaba.com>
Date:   Mon,  2 Mar 2020 19:00:13 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     cgroups@...r.kernel.org, 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
Cc:     Alex Shi <alex.shi@...ux.alibaba.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v9 03/20] 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 295512465065..914df63948b1 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -31,7 +31,6 @@
 static struct page *page_idle_get_page(unsigned long pfn)
 {
 	struct page *page;
-	pg_data_t *pgdat;
 
 	if (!pfn_valid(pfn))
 		return NULL;
@@ -41,13 +40,6 @@ static struct page *page_idle_get_page(unsigned long pfn)
 	    !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