The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at
https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.5
------>
commit b1d861eea2c7217a8bd6162b93c5a4356d822844
Author: Kirill Tkhai <ktk...@odin.com>
Date: Tue Sep 1 17:08:00 2015 +0400
ms/sched: Fix schedule_tail() to disable preemption
Porting ms commit 1a43a14a5bd9c32dbd7af35e35a5afa703944bcb by Oleg Nesterov:
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 <o...@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Kirill Tkhai <tk...@yandex.ru>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141008193644.ga32...@redhat.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Kirill Tkhai <ktk...@odin.com>
---
kernel/sched/core.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bbb6fc3..30f39a25 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2245,20 +2245,18 @@ static inline void post_schedule(struct rq *rq)
asmlinkage void schedule_tail(struct task_struct *prev)
__releases(rq->lock)
{
- struct rq *rq = this_rq();
+ struct rq *rq;
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
+ /* finish_task_switch() drops rq->lock and enables preemtion */
+ preempt_disable();
+#endif
+ 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);
-
-#ifdef __ARCH_WANT_UNLOCKED_CTXSW
- /* In this case, finish_task_switch does not reenable preemption */
preempt_enable();
-#endif
+
if (current->set_child_tid)
put_user(task_pid_vnr(current), current->set_child_tid);
}
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