lkml.org 
[lkml]   [2011]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:sched/urgent] sched: Check if lowest_mask is initialized in find_lowest_rq()
Commit-ID:  0da938c44921cfb690283d3b0c9c48a10375db2c
Gitweb: http://git.kernel.org/tip/0da938c44921cfb690283d3b0c9c48a10375db2c
Author: Steven Rostedt <rostedt@goodmis.org>
AuthorDate: Tue, 14 Jun 2011 18:36:25 -0400
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 15 Jun 2011 11:44:48 +0200

sched: Check if lowest_mask is initialized in find_lowest_rq()

On system boot up, the lowest_mask is initialized with an
early_initcall(). But RT tasks may wake up on other
early_initcall() callers before the lowest_mask is initialized,
causing a system crash.

Commit "d72bce0e67 rcu: Cure load woes" was the first commit
to wake up RT tasks in early init. Before this commit this bug
should not happen.

Reported-by: Andrew Theurer <habanero@linux.vnet.ibm.com>
Tested-by: Andrew Theurer <habanero@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20110614223657.824872966@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_rt.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 9b8d5dc..10d0182 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1239,6 +1239,10 @@ static int find_lowest_rq(struct task_struct *task)
int this_cpu = smp_processor_id();
int cpu = task_cpu(task);

+ /* Make sure the mask is initialized first */
+ if (unlikely(!lowest_mask))
+ return -1;
+
if (task->rt.nr_cpus_allowed == 1)
return -1; /* No other targets possible */


\
 
 \ /
  Last update: 2011-06-15 11:53    [W:0.051 / U:7.356 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site