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authorOleg Nesterov <oleg@redhat.com>2010-03-15 12:10:27 +0300
committerIngo Molnar <mingo@elte.hu>2010-04-02 22:12:03 +0400
commit9084bb8246ea935b98320554229e2f371f7f52fa (patch)
tree8478d18125e3b4a7e0a31d702647dee1830d23ef /include/linux/cpuset.h
parent6a1bdc1b577ebcb65f6603c57f8347309bc4ab13 (diff)
downloadlinux-9084bb8246ea935b98320554229e2f371f7f52fa.tar.xz
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 'include/linux/cpuset.h')
-rw-r--r--include/linux/cpuset.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index eeaaee746bee..a73454aec333 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -21,6 +21,7 @@ extern int number_of_cpusets; /* How many cpusets are defined in system? */
extern int cpuset_init(void);
extern void cpuset_init_smp(void);
extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
+extern int cpuset_cpus_allowed_fallback(struct task_struct *p);
extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
#define cpuset_current_mems_allowed (current->mems_allowed)
void cpuset_init_current_mems_allowed(void);
@@ -101,6 +102,12 @@ static inline void cpuset_cpus_allowed(struct task_struct *p,
cpumask_copy(mask, cpu_possible_mask);
}
+static inline int cpuset_cpus_allowed_fallback(struct task_struct *p)
+{
+ cpumask_copy(&p->cpus_allowed, cpu_possible_mask);
+ return cpumask_any(cpu_active_mask);
+}
+
static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
{
return node_possible_map;