sched/isolation: Move isolcpus= handling to the housekeeping code

We want to centralize the isolation features, to be done by the housekeeping
subsystem and scheduler domain isolation is a significant part of it.

No intended behaviour change, we just reuse the housekeeping cpumask
and core code.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-11-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

7 files changed, 73 insertions, 59 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 321cd7b4d817..a73ab95558f5 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -18,6 +18,7 @@
 #include <linux/cpufeature.h>
 #include <linux/tick.h>
 #include <linux/pm_qos.h>
+#include <linux/sched/isolation.h>
 
 #include "base.h"
 
@@ -271,8 +272,16 @@ static ssize_t print_cpus_isolated(struct device *dev,
                                   struct device_attribute *attr, char *buf)
 {
         int n = 0, len = PAGE_SIZE-2;
+        cpumask_var_t isolated;
 
-        n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(cpu_isolated_map));
+        if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
+                return -ENOMEM;
+
+        cpumask_andnot(isolated, cpu_possible_mask,
+                       housekeeping_cpumask(HK_FLAG_DOMAIN));
+        n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(isolated));
+
+        free_cpumask_var(isolated);
 
         return n;
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0f897dfc195e..1b0cc0d6df8d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -165,8 +165,6 @@ struct task_group;
 /* Task command name length: */
 #define TASK_COMM_LEN                   16
 
-extern cpumask_var_t                    cpu_isolated_map;
-
 extern void scheduler_tick(void);
 
 #define MAX_SCHEDULE_TIMEOUT            LONG_MAX
diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index e53cfa96e91e..d849431c8060 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -11,6 +11,7 @@ enum hk_flags {
         HK_FLAG_MISC            = (1 << 2),
         HK_FLAG_SCHED           = (1 << 3),
         HK_FLAG_TICK            = (1 << 4),
+        HK_FLAG_DOMAIN          = (1 << 5),
 };
 
 #ifdef CONFIG_CPU_ISOLATION
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4657e2924ecb..f7efa7b4d825 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -57,7 +57,7 @@
 #include <linux/backing-dev.h>
 #include <linux/sort.h>
 #include <linux/oom.h>
-
+#include <linux/sched/isolation.h>
 #include <linux/uaccess.h>
 #include <linux/atomic.h>
 #include <linux/mutex.h>
@@ -656,7 +656,6 @@ static int generate_sched_domains(cpumask_var_t **domains,
         int csn;                /* how many cpuset ptrs in csa so far */
         int i, j, k;            /* indices for partition finding loops */
         cpumask_var_t *doms;    /* resulting partition; i.e. sched domains */
-        cpumask_var_t non_isolated_cpus;  /* load balanced CPUs */
         struct sched_domain_attr *dattr;  /* attributes for custom domains */
         int ndoms = 0;          /* number of sched domains in result */
         int nslot;              /* next empty doms[] struct cpumask slot */
@@ -666,10 +665,6 @@ static int generate_sched_domains(cpumask_var_t **domains,
         dattr = NULL;
         csa = NULL;
 
-        if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
-                goto done;
-        cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
-
         /* Special case for the 99% of systems with one, full, sched domain */
         if (is_sched_load_balance(&top_cpuset)) {
                 ndoms = 1;
@@ -683,7 +678,7 @@ static int generate_sched_domains(cpumask_var_t **domains,
                         update_domain_attr_tree(dattr, &top_cpuset);
                 }
                 cpumask_and(doms[0], top_cpuset.effective_cpus,
-                                     non_isolated_cpus);
+                            housekeeping_cpumask(HK_FLAG_DOMAIN));
 
                 goto done;
         }
@@ -707,7 +702,8 @@ static int generate_sched_domains(cpumask_var_t **domains,
                  */
                 if (!cpumask_empty(cp->cpus_allowed) &&
                     !(is_sched_load_balance(cp) &&
-                      cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
+                      cpumask_intersects(cp->cpus_allowed,
+                                         housekeeping_cpumask(HK_FLAG_DOMAIN))))
                         continue;
 
                 if (is_sched_load_balance(cp))
@@ -789,7 +785,7 @@ restart:
 
                         if (apn == b->pn) {
                                 cpumask_or(dp, dp, b->effective_cpus);
-                                cpumask_and(dp, dp, non_isolated_cpus);
+                                cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN));
                                 if (dattr)
                                         update_domain_attr_tree(dattr + nslot, b);
 
@@ -802,7 +798,6 @@ restart:
         BUG_ON(nslot != ndoms);
 
 done:
-        free_cpumask_var(non_isolated_cpus);
         kfree(csa);
 
         /*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2210c0203e51..1a55c842bfbc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -84,9 +84,6 @@ __read_mostly int scheduler_running;
  */
 int sysctl_sched_rt_runtime = 950000;
 
-/* CPUs with isolated domains */
-cpumask_var_t cpu_isolated_map;
-
 /*
  * __task_rq_lock - lock the rq @p resides on.
  */
@@ -5735,10 +5732,6 @@ static inline void sched_init_smt(void) { }
 
 void __init sched_init_smp(void)
 {
-        cpumask_var_t non_isolated_cpus;
-
-        alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
-
         sched_init_numa();
 
         /*
@@ -5748,16 +5741,12 @@ void __init sched_init_smp(void)
          */
         mutex_lock(&sched_domains_mutex);
         sched_init_domains(cpu_active_mask);
-        cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
-        if (cpumask_empty(non_isolated_cpus))
-                cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
         mutex_unlock(&sched_domains_mutex);
 
         /* Move init over to a non-isolated CPU */
-        if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
+        if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
                 BUG();
         sched_init_granularity();
-        free_cpumask_var(non_isolated_cpus);
 
         init_sched_rt_class();
         init_sched_dl_class();
@@ -5961,9 +5950,6 @@ void __init sched_init(void)
         calc_load_update = jiffies + LOAD_FREQ;
 
 #ifdef CONFIG_SMP
-        /* May be allocated at isolcpus cmdline parse time */
-        if (cpu_isolated_map == NULL)
-                zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
         idle_thread_set_boot_cpu();
         set_cpu_rq_start_time(smp_processor_id());
 #endif
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 1f61e440358d..8f666bc5abe8 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -63,32 +63,69 @@ void __init housekeeping_init(void)
         WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
 }
 
-#ifdef CONFIG_NO_HZ_FULL
-static int __init housekeeping_nohz_full_setup(char *str)
+static int __init housekeeping_setup(char *str, enum hk_flags flags)
 {
         cpumask_var_t non_housekeeping_mask;
+        int err;
 
         alloc_bootmem_cpumask_var(&non_housekeeping_mask);
-        if (cpulist_parse(str, non_housekeeping_mask) < 0) {
-                pr_warn("Housekeeping: Incorrect nohz_full cpumask\n");
+        err = cpulist_parse(str, non_housekeeping_mask);
+        if (err < 0 || cpumask_last(non_housekeeping_mask) >= nr_cpu_ids) {
+                pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
                 free_bootmem_cpumask_var(non_housekeeping_mask);
                 return 0;
         }
 
-        alloc_bootmem_cpumask_var(&housekeeping_mask);
-        cpumask_andnot(housekeeping_mask, cpu_possible_mask, non_housekeeping_mask);
-
-        if (cpumask_empty(housekeeping_mask))
-                cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
+        if (!housekeeping_flags) {
+                alloc_bootmem_cpumask_var(&housekeeping_mask);
+                cpumask_andnot(housekeeping_mask,
+                               cpu_possible_mask, non_housekeeping_mask);
+                if (cpumask_empty(housekeeping_mask))
+                        cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
+        } else {
+                cpumask_var_t tmp;
+
+                alloc_bootmem_cpumask_var(&tmp);
+                cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask);
+                if (!cpumask_equal(tmp, housekeeping_mask)) {
+                        pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
+                        free_bootmem_cpumask_var(tmp);
+                        free_bootmem_cpumask_var(non_housekeeping_mask);
+                        return 0;
+                }
+                free_bootmem_cpumask_var(tmp);
+        }
 
-        housekeeping_flags = HK_FLAG_TICK | HK_FLAG_TIMER |
-                                HK_FLAG_RCU | HK_FLAG_MISC;
+        if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_TICK)) {
+                if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
+                        tick_nohz_full_setup(non_housekeeping_mask);
+                } else {
+                        pr_warn("Housekeeping: nohz unsupported."
+                                " Build with CONFIG_NO_HZ_FULL\n");
+                        free_bootmem_cpumask_var(non_housekeeping_mask);
+                        return 0;
+                }
+        }
 
-        tick_nohz_full_setup(non_housekeeping_mask);
+        housekeeping_flags |= flags;
 
         free_bootmem_cpumask_var(non_housekeeping_mask);
 
         return 1;
 }
+
+static int __init housekeeping_nohz_full_setup(char *str)
+{
+        unsigned int flags;
+
+        flags = HK_FLAG_TICK | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
+
+        return housekeeping_setup(str, flags);
+}
 __setup("nohz_full=", housekeeping_nohz_full_setup);
-#endif
+
+static int __init housekeeping_isolcpus_setup(char *str)
+{
+        return housekeeping_setup(str, HK_FLAG_DOMAIN);
+}
+__setup("isolcpus=", housekeeping_isolcpus_setup);
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index e3d31b0880dc..2e6b9126ffdc 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -3,6 +3,7 @@
  */
 #include <linux/sched.h>
 #include <linux/mutex.h>
+#include <linux/sched/isolation.h>
 
 #include "sched.h"
 
@@ -469,21 +470,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
         update_top_cache_domain(cpu);
 }
 
-/* Setup the mask of CPUs configured for isolated domains */
-static int __init isolated_cpu_setup(char *str)
-{
-        int ret;
-
-        alloc_bootmem_cpumask_var(&cpu_isolated_map);
-        ret = cpulist_parse(str, cpu_isolated_map);
-        if (ret || cpumask_last(cpu_isolated_map) >= nr_cpu_ids) {
-                pr_err("sched: Error, all isolcpus= values must be between 0 and %u - ignoring them.\n", nr_cpu_ids-1);
-                return 0;
-        }
-        return 1;
-}
-__setup("isolcpus=", isolated_cpu_setup);
-
 struct s_data {
         struct sched_domain ** __percpu sd;
         struct root_domain      *rd;
@@ -1792,7 +1778,7 @@ int sched_init_domains(const struct cpumask *cpu_map)
         doms_cur = alloc_sched_domains(ndoms_cur);
         if (!doms_cur)
                 doms_cur = &fallback_doms;
-        cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
+        cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
         err = build_sched_domains(doms_cur[0], NULL);
         register_sched_domain_sysctl();
 
@@ -1875,7 +1861,8 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
                 doms_new = alloc_sched_domains(1);
                 if (doms_new) {
                         n = 1;
-                        cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
+                        cpumask_and(doms_new[0], cpu_active_mask,
+                                    housekeeping_cpumask(HK_FLAG_DOMAIN));
                 }
         } else {
                 n = ndoms_new;
@@ -1898,7 +1885,8 @@ match1:
         if (!doms_new) {
                 n = 0;
                 doms_new = &fallback_doms;
-                cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
+                cpumask_and(doms_new[0], cpu_active_mask,
+                            housekeeping_cpumask(HK_FLAG_DOMAIN));
         }
 
         /* Build new domains: */