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authorOleg Nesterov <oleg@redhat.com>2010-03-15 10:10:27 +0100
committerIngo Molnar <mingo@elte.hu>2010-04-02 20:12:03 +0200
commit9084bb8246ea935b98320554229e2f371f7f52fa (patch)
tree8478d18125e3b4a7e0a31d702647dee1830d23ef /kernel/sched.c
parent6a1bdc1b577ebcb65f6603c57f8347309bc4ab13 (diff)
sched: Make select_fallback_rq() cpuset friendly
Introduce cpuset_cpus_allowed_fallback() helper to fix the cpuset problems with select_fallback_rq(). It can be called from any context and can't use any cpuset locks including task_lock(). It is called when the task doesn't have online cpus in ->cpus_allowed but ttwu/etc must be able to find a suitable cpu. I am not proud of this patch. Everything which needs such a fat comment can't be good even if correct. But I'd prefer to not change the locking rules in the code I hardly understand, and in any case I believe this simple change make the code much more correct compared to deadlocks we currently have. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100315091027.GA9155@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 11119deffa4..9a38c7a24ed 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2300,9 +2300,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
/* No more Mr. Nice Guy. */
if (unlikely(dest_cpu >= nr_cpu_ids)) {
- cpumask_copy(&p->cpus_allowed, cpu_possible_mask);
- dest_cpu = cpumask_any(cpu_active_mask);
-
+ dest_cpu = cpuset_cpus_allowed_fallback(p);
/*
* Don't tell them about moving exiting tasks or
* kernel threads (both mm NULL), since they never