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authorLi Zefan <lizefan@huawei.com>2014-07-09 16:47:41 +0800
committerTejun Heo <tj@kernel.org>2014-07-09 15:56:16 -0400
commit554b0d1c845e42ef01d7f6f5f24b3e4c6129ce8f (patch)
treef887cbfb24c0f7e2a8c904913a368abb6d28f11c /kernel/cpuset.c
parent734d45130cb4f668fb33d182f6943523628582ef (diff)
downloadlinux-554b0d1c845e42ef01d7f6f5f24b3e4c6129ce8f.tar.bz2
cpuset: inherit ancestor's masks if effective_{cpus, mems} becomes empty
We're going to have separate user-configured masks and effective ones. Eventually configured masks can only be changed by writing cpuset.cpus and cpuset.mems, and they won't be restricted by parent cpuset. While effective masks reflect cpu/memory hotplug and hierachical restriction, and these are the real masks that apply to the tasks in the cpuset. We calculate effective mask this way: - top cpuset's effective_mask == online_mask, otherwise - cpuset's effective_mask == configured_mask & parent effective_mask, if the result is empty, it inherits parent effective mask. Those behavior changes are for default hierarchy only. For legacy hierarchy, effective_mask and configured_mask are the same, so we won't break old interfaces. To make cs->effective_{cpus,mems} to be effective masks, we need to - update the effective masks at hotplug - update the effective masks at config change - take on ancestor's mask when the effective mask is empty The last item is done here. This won't introduce behavior change. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index da766c3736c4..f8340026d01c 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -877,6 +877,13 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some CPUs.
+ */
+ if (cpumask_empty(new_cpus))
+ cpumask_copy(new_cpus, parent->effective_cpus);
+
/* Skip the whole subtree if the cpumask remains the same. */
if (cpumask_equal(new_cpus, cp->effective_cpus)) {
pos_css = css_rightmost_descendant(pos_css);
@@ -1123,6 +1130,13 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some MEMs.
+ */
+ if (nodes_empty(*new_mems))
+ *new_mems = parent->effective_mems;
+
/* Skip the whole subtree if the nodemask remains the same. */
if (nodes_equal(*new_mems, cp->effective_mems)) {
pos_css = css_rightmost_descendant(pos_css);
@@ -2102,7 +2116,11 @@ retry:
mutex_lock(&callback_mutex);
cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, &off_cpus);
+
+ /* Inherit the effective mask of the parent, if it becomes empty. */
cpumask_andnot(cs->effective_cpus, cs->effective_cpus, &off_cpus);
+ if (on_dfl && cpumask_empty(cs->effective_cpus))
+ cpumask_copy(cs->effective_cpus, parent_cs(cs)->effective_cpus);
mutex_unlock(&callback_mutex);
/*
@@ -2117,7 +2135,11 @@ retry:
mutex_lock(&callback_mutex);
nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
+
+ /* Inherit the effective mask of the parent, if it becomes empty */
nodes_andnot(cs->effective_mems, cs->effective_mems, off_mems);
+ if (on_dfl && nodes_empty(cs->effective_mems))
+ cs->effective_mems = parent_cs(cs)->effective_mems;
mutex_unlock(&callback_mutex);
/*