From b1296cc48b39355241470ef934a5e2270e3f23bd Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" 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 Cc: Pavel Machek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index db023e2ff385..56651a10c366 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; } -- 2.20.1