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authorJuri Lelli <juri.lelli@arm.com>2014-10-07 12:52:11 +0400
committerIngo Molnar <mingo@kernel.org>2014-10-28 12:48:00 +0300
commitf82f80426f7afcf55953924e71555984a4bd6ce6 (patch)
tree3a3e15c85f04c11d8f9bc0708b4c8ca439d3431b /kernel/cpuset.c
parent7f51412a415d87ea8598d14722fb31e4f5701257 (diff)
downloadlinux-f82f80426f7afcf55953924e71555984a4bd6ce6.tar.xz
sched/deadline: Ensure that updates to exclusive cpusets don't break AC
How we deal with updates to exclusive cpusets is currently broken. As an example, suppose we have an exclusive cpuset composed of two cpus: A[cpu0,cpu1]. We can assign SCHED_DEADLINE task to it up to the allowed bandwidth. If we want now to modify cpusetA's cpumask, we have to check that removing a cpu's amount of bandwidth doesn't break AC guarantees. This thing isn't checked in the current code. This patch fixes the problem above, denying an update if the new cpumask won't have enough bandwidth for SCHED_DEADLINE tasks that are currently active. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Li Zefan <lizefan@huawei.com> Cc: cgroups@vger.kernel.org Link: http://lkml.kernel.org/r/5433E6AF.5080105@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7af8577fc8f8..723cfc9d0ad7 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -506,6 +506,16 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
goto out;
}
+ /*
+ * We can't shrink if we won't have enough room for SCHED_DEADLINE
+ * tasks.
+ */
+ ret = -EBUSY;
+ if (is_cpu_exclusive(cur) &&
+ !cpuset_cpumask_can_shrink(cur->cpus_allowed,
+ trial->cpus_allowed))
+ goto out;
+
ret = 0;
out:
rcu_read_unlock();