2015-04-17 18:59:42

by Jiri Kosina

[permalink] [raw]
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 <[email protected]>
---

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