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authorSteven Rostedt <rostedt@goodmis.org>2011-06-14 18:36:25 -0400
committerIngo Molnar <mingo@elte.hu>2011-06-15 11:44:48 +0200
commit0da938c44921cfb690283d3b0c9c48a10375db2c (patch)
tree7e9374a3ed16a4118f2f5d600067c471aaa80c70 /kernel/sched_rt.c
parent8dd0de8be31b4b966d17750a0b10df2f575c91ac (diff)
downloadlinux-0da938c44921cfb690283d3b0c9c48a10375db2c.tar.bz2
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>
Diffstat (limited to 'kernel/sched_rt.c')
-rw-r--r--kernel/sched_rt.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 9b8d5dce946e..10d018212bab 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 */