From: Mike Galbraith <efault@gmx.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Hillf Danton <dhillf@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Yong Zhang <yong.zhang0@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] sched, rt: fix rq->rt.pushable_tasks bug in push_rt_task()
Date: Wed, 01 Jun 2011 04:29:45 +0200 [thread overview]
Message-ID: <1306895385.4791.26.camel@marge.simson.net> (raw)
In-Reply-To: <1306894493.4791.16.camel@marge.simson.net>
Stupid mouse (driver) grabbed wrong text blob.
From: Hillf Danton <dhillf@gmail.com>
sched, rt: fix rq->rt.pushable_tasks bug in push_rt_task()
Do not call dequeue_pushable_task() when failing to push an eligible
task, as it remains pushable, merely not at this particular moment.
Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Mike Galbraith <mgalbraith@gmx.de>
---
kernel/sched_rt.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
Index: linux-2.6.40.git/kernel/sched_rt.c
===================================================================
--- linux-2.6.40.git.orig/kernel/sched_rt.c
+++ linux-2.6.40.git/kernel/sched_rt.c
@@ -1378,6 +1378,7 @@ static int push_rt_task(struct rq *rq)
{
struct task_struct *next_task;
struct rq *lowest_rq;
+ int ret = 0;
if (!rq->rt.overloaded)
return 0;
@@ -1410,7 +1411,7 @@ retry:
if (!lowest_rq) {
struct task_struct *task;
/*
- * find lock_lowest_rq releases rq->lock
+ * find_lock_lowest_rq releases rq->lock
* so it is possible that next_task has migrated.
*
* We need to make sure that the task is still on the same
@@ -1420,12 +1421,11 @@ retry:
task = pick_next_pushable_task(rq);
if (task_cpu(next_task) == rq->cpu && task == next_task) {
/*
- * If we get here, the task hasn't moved at all, but
- * it has failed to push. We will not try again,
- * since the other cpus will pull from us when they
- * are ready.
+ * The task hasn't migrated, and is still the next
+ * eligible task, but we failed to find a run-queue
+ * to push it to. Do not retry in this case, since
+ * other cpus will pull from us when ready.
*/
- dequeue_pushable_task(rq, next_task);
goto out;
}
@@ -1444,6 +1444,7 @@ retry:
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
activate_task(lowest_rq, next_task, 0);
+ ret = 1;
resched_task(lowest_rq->curr);
@@ -1452,7 +1453,7 @@ retry:
out:
put_task_struct(next_task);
- return 1;
+ return ret;
}
static void push_rt_tasks(struct rq *rq)
next prev parent reply other threads:[~2011-06-01 2:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-30 13:39 [PATCH] sched: fix rt_nr_migratory corruption raised in push_rt_task() Hillf Danton
2011-05-31 7:36 ` Mike Galbraith
2011-05-31 13:56 ` Hillf Danton
2011-05-31 15:08 ` Steven Rostedt
2011-06-01 2:14 ` [PATCH] sched, rt: fix rq->rt.pushable_tasks bug " Mike Galbraith
2011-06-01 2:29 ` Mike Galbraith [this message]
2011-08-14 16:02 ` [tip:sched/core] sched, rt: Fix " tip-bot for Hillf Danton
2011-06-01 2:21 ` [PATCH] sched: fix rt_nr_migratory corruption raised " Mike Galbraith
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