Commit f5813d94 authored Jan 07, 2009 by Miao Xie Committed by Linus Torvalds Jan 08, 2009

cpusets: set task's cpu_allowed to cpu_possible_map when attaching it into top cpuset



I found a bug on my dual-cpu box.  I created a sub cpuset in top cpuset
and assign 1 to its cpus.  And then we attach some tasks into this sub
cpuset.  After this, we offline CPU1.  Now, the tasks in this new cpuset
are moved into top cpuset automatically because there is no cpu in sub
cpuset.  Then we online CPU1, we find all the tasks which doesn't belong
to top cpuset originally just run on CPU0.

We fix this bug by setting task's cpu_allowed to cpu_possible_map when
attaching it into top cpuset.  This method needn't modify the current
behavior of cpusets on CPU hotplug, and all of tasks in top cpuset use
cpu_possible_map to initialize their cpu_allowed.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 13337714

kernel/cpuset.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -1338,10 +1338,14 @@ static void cpuset_attach(struct cgroup_subsys *ss,
		struct cpuset *oldcs = cgroup_cs(oldcont);
		int err;

		if (cs == &top_cpuset) {
		cpus = cpu_possible_map;
		} else {
		mutex_lock(&callback_mutex);
		guarantee_online_cpus(cs, &cpus);
		err = set_cpus_allowed_ptr(tsk, &cpus);
		mutex_unlock(&callback_mutex);
		}
		err = set_cpus_allowed_ptr(tsk, &cpus);
		if (err)
		return;

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