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cpuset: fix possible races in cpu/memory hotplug

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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: Li 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan 2009-04-02 16:57:49 -07:00 committed by Linus Torvalds
parent 83aae4c737
commit 0b4217b3fd
1 changed files with 6 additions and 3 deletions
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9
kernel/cpuset.c
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@ -2070,7 +2070,9 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
} }
cgroup_lock(); cgroup_lock();
mutex_lock(&callback_mutex);
cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask); cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
mutex_unlock(&callback_mutex);
scan_for_empty_cpusets(&top_cpuset); scan_for_empty_cpusets(&top_cpuset);
ndoms = generate_sched_domains(&doms, &attr); ndoms = generate_sched_domains(&doms, &attr);
cgroup_unlock(); cgroup_unlock();
@ -2093,11 +2095,12 @@ static int cpuset_track_online_nodes(struct notifier_block *self,
cgroup_lock(); cgroup_lock();
switch (action) { switch (action) {
case MEM_ONLINE: case MEM_ONLINE:
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
break;
case MEM_OFFLINE: case MEM_OFFLINE:
mutex_lock(&callback_mutex);
top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
scan_for_empty_cpusets(&top_cpuset); mutex_unlock(&callback_mutex);
if (action == MEM_OFFLINE)
scan_for_empty_cpusets(&top_cpuset);
break; break;
default: default:
break; break;