From b1296cc48b39355241470ef934a5e2270e3f23bd Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Sun, 6 May 2007 14:50:48 -0700
Subject: [PATCH] freezer: fix racy usage of try_to_freeze in kswapd
Currently we can miss freeze_process()->signal_wake_up() in kswapd() if it
happens between try_to_freeze() and prepare_to_wait(). To prevent this
from happening we should check freezing(current) before calling schedule().
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/vmscan.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index db023e2ff3852..56651a10c3664 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1323,8 +1323,6 @@ static int kswapd(void *p)
for ( ; ; ) {
unsigned long new_order;
- try_to_freeze();
-
prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
new_order = pgdat->kswapd_max_order;
pgdat->kswapd_max_order = 0;
@@ -1335,12 +1333,19 @@ static int kswapd(void *p)
*/
order = new_order;
} else {
- schedule();
+ if (!freezing(current))
+ schedule();
+
order = pgdat->kswapd_max_order;
}
finish_wait(&pgdat->kswapd_wait, &wait);
- balance_pgdat(pgdat, order);
+ if (!try_to_freeze()) {
+ /* We can speed up thawing tasks if we don't call
+ * balance_pgdat after returning from the refrigerator
+ */
+ balance_pgdat(pgdat, order);
+ }
}
return 0;
}
--
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