There are a number of different reasons which can cause a partition to become invalid. A user seeing an invalid partition may not know exactly why. To help user to get a better understanding of the underlying reason, The cpuset.cpus.partition control file, when read, will now report the reason why a partition become invalid. When a partition does become invalid, reading the control file will show "root invalid (<reason>)" where <reason> is a string that describes why the partition is invalid.
Signed-off-by: Waiman Long longman@redhat.com --- kernel/cgroup/cpuset.c | 58 ++++++++++++++++++++++++++++++++++++++---- 1 file changed, 53 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index cfab10911682..d1025470b9ea 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -85,6 +85,26 @@ struct fmeter { spinlock_t lock; /* guards read or write of above */ };
+/* + * Invalid partition error code + */ +enum prs_errcode { + PERR_NONE = 0, + PERR_INVCPUS, + PERR_INVPARENT, + PERR_NOTPART, + PERR_NOCPUS, + PERR_HOTPLUG, +}; + +static const char * const perr_strings[] = { + [PERR_INVCPUS] = "Invalid change to cpuset.cpus", + [PERR_INVPARENT] = "Parent is an invalid partition root", + [PERR_NOTPART] = "Parent is not a partition root", + [PERR_NOCPUS] = "Parent unable to distribute cpu downstream", + [PERR_HOTPLUG] = "No cpu available due to hotplug", +}; + struct cpuset { struct cgroup_subsys_state css;
@@ -168,6 +188,9 @@ struct cpuset { int use_parent_ecpus; int child_ecpus_count;
+ /* Invalid partition error code, not lock protected */ + enum prs_errcode prs_err; + /* Handle for cpuset.cpus.partition */ struct cgroup_file partition_file; }; @@ -282,8 +305,13 @@ static inline int is_partition_root(const struct cpuset *cs) static inline void notify_partition_change(struct cpuset *cs, int old_prs, int new_prs) { - if (old_prs != new_prs) - cgroup_file_notify(&cs->partition_file); + if (old_prs == new_prs) + return; + cgroup_file_notify(&cs->partition_file); + + /* Reset prs_err if not invalid */ + if (new_prs != PRS_ERROR) + WRITE_ONCE(cs->prs_err, PERR_NONE); }
static struct cpuset top_cpuset = { @@ -1292,6 +1320,9 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, part_error = partition_is_populated(parent, cpuset) && cpumask_subset(parent->effective_cpus, tmp->addmask) && !cpumask_intersects(tmp->delmask, cpu_active_mask); + + if ((READ_ONCE(cpuset->prs_err) == PERR_NONE) && part_error) + WRITE_ONCE(cpuset->prs_err, PERR_INVCPUS); } else { /* * partcmd_update w/o newmask: @@ -1315,6 +1346,9 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, !parent->nr_subparts_cpus) || (cpumask_equal(parent->effective_cpus, tmp->addmask) && partition_is_populated(parent, cpuset)); + + if (is_partition_root(cpuset) && part_error) + WRITE_ONCE(cpuset->prs_err, PERR_NOCPUS); }
if (cmd == partcmd_update) { @@ -1471,6 +1505,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, * invalid too. */ new_prs = PRS_ERROR; + WRITE_ONCE(cp->prs_err, + (parent->partition_root_state == PRS_ERROR) + ? PERR_INVPARENT : PERR_NOTPART); break; } } @@ -2632,7 +2669,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) static int sched_partition_show(struct seq_file *seq, void *v) { struct cpuset *cs = css_cs(seq_css(seq)); - const char *type; + const char *err, *type;
switch (cs->partition_root_state) { case PRS_ENABLED: @@ -2646,7 +2683,11 @@ static int sched_partition_show(struct seq_file *seq, void *v) break; case PRS_ERROR: type = is_sched_load_balance(cs) ? "root" : "isolated"; - seq_printf(seq, "%s invalid\n", type); + err = perr_strings[READ_ONCE(cs->prs_err)]; + if (err) + seq_printf(seq, "%s invalid (%s)\n", type, err); + else + seq_printf(seq, "%s invalid\n", type); break; } return 0; @@ -3236,7 +3277,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) if (is_partition_root(cs) && ((cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) || !parent->nr_subparts_cpus)) { - int old_prs; + int old_prs, parent_prs;
update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp); @@ -3249,10 +3290,17 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) }
old_prs = cs->partition_root_state; + parent_prs = parent->partition_root_state; if (old_prs != PRS_ERROR) { spin_lock_irq(&callback_lock); cs->partition_root_state = PRS_ERROR; spin_unlock_irq(&callback_lock); + if (parent_prs == PRS_ERROR) + WRITE_ONCE(cs->prs_err, PERR_INVPARENT); + else if (!parent_prs) + WRITE_ONCE(cs->prs_err, PERR_NOTPART); + else + WRITE_ONCE(cs->prs_err, PERR_HOTPLUG); notify_partition_change(cs, old_prs, PRS_ERROR); } cpuset_force_rebuild();