diff options
authorDmitry Adamushko <>2008-06-30 20:22:34 +0400
committerGreg Kroah-Hartman <>2008-07-03 07:46:15 +0400
commit0758c2f30b75419fbe5e0ec6dfc892bbc0687f57 (patch)
parent1e9a615bfce7996ea4d815d45d364b47ac6a74e8 (diff)
sched: fix cpu hotplug
Commit 79c537998d143b127c8c662a403c3356cb885f1c upstream the CPU hotplug problems (crashes under high-volume unplug+replug tests) seem to be related to migrate_dead_tasks(). Firstly I added traces to see all tasks being migrated with migrate_live_tasks() and migrate_dead_tasks(). On my setup the problem pops up (the one with "se == NULL" in the loop of pick_next_task_fair()) shortly after the traces indicate that some has been migrated with migrate_dead_tasks()). btw., I can reproduce it much faster now with just a plain cpu down/up loop. [disclaimer] Well, unless I'm really missing something important in this late hour [/desclaimer] pick_next_task() is not something appropriate for migrate_dead_tasks() :-) the following change seems to eliminate the problem on my setup (although, I kept it running only for a few minutes to get a few messages indicating migrate_dead_tasks() does move tasks and the system is still ok) Signed-off-by: Ingo Molnar <> Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 1e4596c68dd0..c54077ca1ed1 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5728,6 +5728,7 @@ static void migrate_dead_tasks(unsigned int dead_cpu)
next = pick_next_task(rq, rq->curr);
if (!next)
+ next->sched_class->put_prev_task(rq, next);
migrate_dead(dead_cpu, next);