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| author | Oleg Nesterov <oleg@redhat.com> | 2010-03-15 10:10:27 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-04-02 20:12:03 +0200 |
| commit | 9084bb8246ea935b98320554229e2f371f7f52fa (patch) | |
| tree | 8478d18125e3b4a7e0a31d702647dee1830d23ef /kernel/sched.c | |
| parent | sched: _cpu_down(): Don't play with current->cpus_allowed (diff) | |
| download | linux-9084bb8246ea935b98320554229e2f371f7f52fa.tar.xz linux-9084bb8246ea935b98320554229e2f371f7f52fa.zip | |
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.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 11119deffa48..9a38c7a24ed7 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 |