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Commit 0b4217b3 authored by Li Zefan's avatar Li Zefan Committed by Linus Torvalds
Browse files

cpuset: fix possible races in cpu/memory hotplug 



Change to cpuset->cpus_allowed and cpuset->mems_allowed should be protected
by callback_mutex, otherwise the reader may read wrong cpus/mems. This is
cpuset's lock rule.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 83aae4c7

kernel/cpuset.c

+6 −3
Original line number Diff line number Diff line
@@ -2070,7 +2070,9 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb, 
	}



	cgroup_lock();

	mutex_lock(&callback_mutex);

	cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);

	mutex_unlock(&callback_mutex);

	scan_for_empty_cpusets(&top_cpuset);

	ndoms = generate_sched_domains(&doms, &attr);

	cgroup_unlock();
@@ -2093,10 +2095,11 @@ static int cpuset_track_online_nodes(struct notifier_block *self, 
	cgroup_lock();

	switch (action) {

	case MEM_ONLINE:

		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];

		break;

	case MEM_OFFLINE:

		mutex_lock(&callback_mutex);

		top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];

		mutex_unlock(&callback_mutex);

		if (action == MEM_OFFLINE)

			scan_for_empty_cpusets(&top_cpuset);

		break;

	default: