linux-kernel - [PATCH] thp: cleanup how khugepaged enters freezer

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Date:	Fri, 17 Apr 2015 20:59:39 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>
cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] thp: cleanup how khugepaged enters freezer

khugepaged_do_scan() checks in every iteration whether freezing(current) 
is true, and in such case breaks out of the loop, which causes 
try_to_freeze() to be called immediately afterwards in 
khugepaged_wait_work().

If nothing else, this causes unnecessary freezing(current) test, and also 
makes the way khugepaged enters freezer a bit less obvious than necessary.

Let's just try to freeze directly, instead of splitting it into two 
(directly adjacent) phases.

Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---

Stumbled upon this when debugging something completely unrelated.

 mm/huge_memory.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 078832c..b3d8cd8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2799,7 +2799,7 @@ static void khugepaged_do_scan(void)
 
 		cond_resched();
 
-		if (unlikely(kthread_should_stop() || freezing(current)))
+		if (unlikely(kthread_should_stop() || try_to_freeze()))
 			break;
 
 		spin_lock(&khugepaged_mm_lock);
@@ -2820,8 +2820,6 @@ static void khugepaged_do_scan(void)
 
 static void khugepaged_wait_work(void)
 {
-	try_to_freeze();
-
 	if (khugepaged_has_work()) {
 		if (!khugepaged_scan_sleep_millisecs)
 			return;

-- 
Jiri Kosina
SUSE Labs
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