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 | 93 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 75 insertions(+), 18 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index dde45a16deec..261974f5bb3c 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -85,6 +85,30 @@ 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_NOTEXCL, + PERR_NOCPUS, + PERR_HOTPLUG, + PERR_CPUSEMPTY, +}; + +static const char * const perr_strings[] = { + [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus", + [PERR_INVPARENT] = "Parent is an invalid partition root", + [PERR_NOTPART] = "Parent is not a partition root", + [PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive", + [PERR_NOCPUS] = "Parent unable to distribute cpu downstream", + [PERR_HOTPLUG] = "No cpu available due to hotplug", + [PERR_CPUSEMPTY] = "cpuset.cpus is empty", +}; + struct cpuset { struct cgroup_subsys_state css;
@@ -168,6 +192,9 @@ 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; }; @@ -294,6 +321,10 @@ static inline void notify_partition_change(struct cpuset *cs, int old_prs) if (old_prs == cs->partition_root_state) return; cgroup_file_notify(&cs->partition_file); + + /* Reset prs_err if not invalid */ + if (is_partition_valid(cs)) + WRITE_ONCE(cs->prs_err, PERR_NONE); }
static struct cpuset top_cpuset = { @@ -1231,7 +1262,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, * @cmd: Partition root state change command * @newmask: Optional new cpumask for partcmd_update * @tmp: Temporary addmask and delmask - * Return: 0 or -1 (error) + * Return: 0 or a partition root state error code * * For partcmd_enable, the cpuset is being transformed from a non-partition * root to a partition root. The cpus_allowed mask of the given cpuset will @@ -1257,7 +1288,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, * * The partcmd_update command is used by update_cpumasks_hier() with newmask * NULL and update_cpumask() with newmask set. The callers won't check for - * error and so partition_root_state will be updated directly. + * error and so partition_root_state and prs_error will be updated directly. */ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, struct cpumask *newmask, @@ -1267,7 +1298,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, int adding; /* Moving cpus from effective_cpus to subparts_cpus */ int deleting; /* Moving cpus from subparts_cpus to effective_cpus */ int old_prs, new_prs; - bool part_error = false; /* Partition error? */ + int part_error = PERR_NONE; /* Partition error? */
percpu_rwsem_assert_held(&cpuset_rwsem);
@@ -1276,10 +1307,13 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, * The new cpumask, if present, or the current cpus_allowed must * not be empty. */ - if (!is_partition_valid(parent) || - (newmask && cpumask_empty(newmask)) || + if (!is_partition_valid(parent)) { + return is_partition_invalid(parent) + ? PERR_INVPARENT : PERR_NOTPART; + } + if ((newmask && cpumask_empty(newmask)) || (!newmask && cpumask_empty(cs->cpus_allowed))) - return -1; + return PERR_CPUSEMPTY;
adding = deleting = false; old_prs = new_prs = cs->partition_root_state; @@ -1289,7 +1323,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, * doesn't overlap parent's cpus_allowed. */ if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed)) - return -1; + return PERR_INVCPUS;
/* * A parent can be left with no CPU as long as there is no @@ -1297,7 +1331,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, */ if (!cpumask_intersects(cs->cpus_allowed, parent->effective_cpus) && partition_is_populated(parent, cs)) - return -1; + return PERR_NOCPUS;
cpumask_copy(tmp->addmask, cs->cpus_allowed); adding = true; @@ -1334,7 +1368,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, cpumask_subset(parent->effective_cpus, tmp->addmask) && !cpumask_intersects(tmp->delmask, cpu_active_mask) && partition_is_populated(parent, cs)) { - part_error = true; + part_error = PERR_NOCPUS; adding = false; deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, parent->subparts_cpus); @@ -1366,7 +1400,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, (adding && cpumask_subset(parent->effective_cpus, tmp->addmask) && partition_is_populated(parent, cs))) { - part_error = true; + part_error = PERR_NOCPUS; adding = false; }
@@ -1375,6 +1409,8 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, parent->subparts_cpus); } + if (part_error) + WRITE_ONCE(cs->prs_err, part_error);
if (cmd == partcmd_update) { /* @@ -1405,7 +1441,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, if ((old_prs != new_prs) && is_prs_invalid(old_prs)) { if (!is_cpu_exclusive(cs) && (update_flag(CS_CPU_EXCLUSIVE, cs, 1) < 0)) - return -1; + return PERR_NOTEXCL; }
/* @@ -1538,6 +1574,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, */ if (is_partition_valid(cp)) new_prs = -cp->partition_root_state; + WRITE_ONCE(cp->prs_err, + is_partition_invalid(parent) + ? PERR_INVPARENT : PERR_NOTPART); break; } } @@ -2112,13 +2151,13 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, * update_prstate - update partition_root_state * @cs: the cpuset to update * @new_prs: new partition root state - * Return: 0 if successful, < 0 if error + * Return: 0 if successful, != 0 if error * * Call with cpuset_rwsem held. */ static int update_prstate(struct cpuset *cs, int new_prs) { - int err = 0, old_prs = cs->partition_root_state; + int err = PERR_NONE, old_prs = cs->partition_root_state; bool sched_domain_rebuilt = false; struct cpuset *parent = parent_cs(cs); struct tmpmasks tmpmask; @@ -2145,13 +2184,15 @@ static int update_prstate(struct cpuset *cs, int new_prs) * cannot be empty. */ if (cpumask_empty(cs->cpus_allowed)) { - err = 1; + err = PERR_CPUSEMPTY; goto out; }
err = update_flag(CS_CPU_EXCLUSIVE, cs, 1); - if (err) + if (err) { + err = PERR_NOTEXCL; goto out; + }
err = update_parent_subparts_cpumask(cs, partcmd_enable, NULL, &tmpmask); @@ -2723,6 +2764,7 @@ 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 *err, *type = NULL;
switch (cs->partition_root_state) { case PRS_ROOT: @@ -2735,9 +2777,17 @@ static int sched_partition_show(struct seq_file *seq, void *v) seq_puts(seq, "member\n"); break; case PRS_INVALID_ROOT: - seq_puts(seq, "root invalid\n"); - break; + type = "root"; + fallthrough; case PRS_INVALID_ISOLATED: + if (!type) + type = "isolated"; + 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; seq_puts(seq, "isolated invalid\n"); break; } @@ -3328,7 +3378,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) */ if (is_partition_valid(cs) && (!parent->nr_subparts_cpus || (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) { - int old_prs; + int old_prs, parent_prs;
update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp); if (cs->nr_subparts_cpus) { @@ -3340,10 +3390,17 @@ 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 (is_partition_valid(cs)) { spin_lock_irq(&callback_lock); set_partition_invalid(cs); spin_unlock_irq(&callback_lock); + if (is_prs_invalid(parent_prs)) + 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); } cpuset_force_rebuild();