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authorOleg Nesterov <oleg@redhat.com>2014-10-08 21:36:44 +0200
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:47:54 +0100
commit1a43a14a5bd9c32dbd7af35e35a5afa703944bcb (patch)
treedbbef5740b8e0851eef0c19760e548529076613c /kernel/sched
parent8f9fbf092cd0ae31722b42c9abb427a87d55c18a (diff)
downloadop-kernel-dev-1a43a14a5bd9c32dbd7af35e35a5afa703944bcb.zip
op-kernel-dev-1a43a14a5bd9c32dbd7af35e35a5afa703944bcb.tar.gz
sched: Fix schedule_tail() to disable preemption
finish_task_switch() enables preemption, so post_schedule(rq) can be called on the wrong (and even dead) CPU. Afaics, nothing really bad can happen, but in this case we can wrongly clear rq->post_schedule on that CPU. And this simply looks wrong in any case. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20141008193644.GA32055@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cde8481..b493560 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2309,15 +2309,14 @@ static inline void post_schedule(struct rq *rq)
asmlinkage __visible void schedule_tail(struct task_struct *prev)
__releases(rq->lock)
{
- struct rq *rq = this_rq();
+ struct rq *rq;
+ /* finish_task_switch() drops rq->lock and enables preemtion */
+ preempt_disable();
+ rq = this_rq();
finish_task_switch(rq, prev);
-
- /*
- * FIXME: do we need to worry about rq being invalidated by the
- * task_switch?
- */
post_schedule(rq);
+ preempt_enable();
if (current->set_child_tid)
put_user(task_pid_vnr(current), current->set_child_tid);
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