diff options
authorDmitry Adamushko <>2008-06-29 00:16:56 +0200
committerIngo Molnar <>2008-06-29 08:50:21 +0200
commit79c537998d143b127c8c662a403c3356cb885f1c (patch)
parent543cf4cb3fe6f6cae3651ba918b9c56200b257d0 (diff)
sched: fix cpu hotplug
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 <>
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 3aaa5c8cb42..a66e85639de 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5887,6 +5887,7 @@ 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);