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Commit f2809d61 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core-fixes-for-linus' of... 

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: Fix RCU lockdep splat on freezer_fork path
  rcu: Fix RCU lockdep splat in set_task_cpu on fork path
  mutex: Don't spin when the owner CPU is offline or other weird cases
parents d93ac51c 8b46f880

kernel/cgroup_freezer.c

+4 −1
Original line number Diff line number Diff line
@@ -205,9 +205,12 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task) 
	 * No lock is needed, since the task isn't on tasklist yet,

	 * so it can't be moved to another cgroup, which means the

	 * freezer won't be removed and will be valid during this

	 * function call.

	 * function call.  Nevertheless, apply RCU read-side critical

	 * section to suppress RCU lockdep false positives.

	 */

	rcu_read_lock();

	freezer = task_freezer(task);

	rcu_read_unlock();



	/*

	 * The root cgroup is non-freezable, so we can skip the

kernel/sched.c

+14 −4
Original line number Diff line number Diff line
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p) 
/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */

static inline void set_task_rq(struct task_struct *p, unsigned int cpu)

{

	/*

	 * Strictly speaking this rcu_read_lock() is not needed since the

	 * task_group is tied to the cgroup, which in turn can never go away

	 * as long as there are tasks attached to it.

	 *

	 * However since task_group() uses task_subsys_state() which is an

	 * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.

	 */

	rcu_read_lock();

#ifdef CONFIG_FAIR_GROUP_SCHED

	p->se.cfs_rq = task_group(p)->cfs_rq[cpu];

	p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu) 
	p->rt.rt_rq  = task_group(p)->rt_rq[cpu];

	p->rt.parent = task_group(p)->rt_se[cpu];

#endif

	rcu_read_unlock();

}



#else
@@ -3780,7 +3790,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) 
	 * the mutex owner just released it and exited.

	 */

	if (probe_kernel_address(&owner->cpu, cpu))

		goto out;

		return 0;

#else

	cpu = owner->cpu;

#endif
@@ -3790,14 +3800,14 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) 
	 * the cpu field may no longer be valid.

	 */

	if (cpu >= nr_cpumask_bits)

		goto out;

		return 0;



	/*

	 * We need to validate that we can do a

	 * get_cpu() and that we have the percpu area.

	 */

	if (!cpu_online(cpu))

		goto out;

		return 0;



	rq = cpu_rq(cpu);
@@ -3816,7 +3826,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner) 


		cpu_relax();

	}

out:



	return 1;

}

#endif