[PATCH] sched/isolation: allow isolcpus and nohz_full for different cpus

[Li RongQing]

when both isolcpus and nohz_full are set, their cpus must be
same now, in fact isolcpus and nohz_full are not related, and
different cpus are expected for some cases, for example, some
cores for polling threads wants to isolcpus, and some cores for
dedicated threads, only nohz_full is expected

so define two housekeeping mask to save these two configuration
separately and make cpus same only when both nohz_full and
isolcpus with nohz are passed into kernel

fix a build error when CONFIG_CPUMASK_OFFSTACK is not configured
reported by kbuild test robot <lkp@xxxxxxxxx>

Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
 kernel/sched/isolation.c | 80 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 54 insertions(+), 26 deletions(-)

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 008d6ac2342b..f2331c443121 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -11,7 +11,8 @@
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
 EXPORT_SYMBOL_GPL(housekeeping_overridden);
-static cpumask_var_t housekeeping_mask;
+static cpumask_var_t housekeeping_mask_isolcpus;
+static cpumask_var_t housekeeping_mask_nohz_full;
 static unsigned int housekeeping_flags;
 
 bool housekeeping_enabled(enum hk_flags flags)
@@ -20,12 +21,27 @@ bool housekeeping_enabled(enum hk_flags flags)
 }
 EXPORT_SYMBOL_GPL(housekeeping_enabled);
 
+static struct cpumask *housekeeping_get_mask(enum hk_flags flags)
+{
+	if (flags & (HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ))
+		return housekeeping_mask_isolcpus;
+
+	/* set by isolcpus=nohz only */
+	if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_RCU))
+		return housekeeping_mask_isolcpus;
+
+	return housekeeping_mask_nohz_full;
+}
+
 int housekeeping_any_cpu(enum hk_flags flags)
 {
 	int cpu;
 
 	if (static_branch_unlikely(&housekeeping_overridden)) {
 		if (housekeeping_flags & flags) {
+			struct cpumask *housekeeping_mask;
+
+			housekeeping_mask = housekeeping_get_mask(flags);
 			cpu = sched_numa_find_closest(housekeeping_mask, smp_processor_id());
 			if (cpu < nr_cpu_ids)
 				return cpu;
@@ -41,7 +57,7 @@ const struct cpumask *housekeeping_cpumask(enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
 		if (housekeeping_flags & flags)
-			return housekeeping_mask;
+			return housekeeping_get_mask(flags);
 	return cpu_possible_mask;
 }
 EXPORT_SYMBOL_GPL(housekeeping_cpumask);
@@ -49,16 +65,24 @@ EXPORT_SYMBOL_GPL(housekeeping_cpumask);
 void housekeeping_affine(struct task_struct *t, enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
-		if (housekeeping_flags & flags)
+		if (housekeeping_flags & flags) {
+			struct cpumask *housekeeping_mask;
+
+			housekeeping_mask = housekeeping_get_mask(flags);
 			set_cpus_allowed_ptr(t, housekeeping_mask);
+		}
 }
 EXPORT_SYMBOL_GPL(housekeeping_affine);
 
 bool housekeeping_test_cpu(int cpu, enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
-		if (housekeeping_flags & flags)
+		if (housekeeping_flags & flags) {
+			struct cpumask *housekeeping_mask;
+
+			housekeeping_mask = housekeeping_get_mask(flags);
 			return cpumask_test_cpu(cpu, housekeeping_mask);
+		}
 	return true;
 }
 EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
@@ -74,10 +98,14 @@ void __init housekeeping_init(void)
 		sched_tick_offload_init();
 
 	/* We need at least one CPU to handle housekeeping work */
-	WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
+	if (housekeeping_flags & (HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ))
+		WARN_ON_ONCE(cpumask_empty(housekeeping_mask_isolcpus));
+	if (housekeeping_flags & HK_FLAG_TICK)
+		WARN_ON_ONCE(cpumask_empty(housekeeping_mask_nohz_full));
 }
 
-static int __init housekeeping_setup(char *str, enum hk_flags flags)
+static int __init housekeeping_setup(char *str, enum hk_flags flags,
+		cpumask_var_t *housekeeping_mask)
 {
 	cpumask_var_t non_housekeeping_mask;
 	cpumask_var_t tmp;
@@ -92,25 +120,25 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags)
 	}
 
 	alloc_bootmem_cpumask_var(&tmp);
-	if (!housekeeping_flags) {
-		alloc_bootmem_cpumask_var(&housekeeping_mask);
-		cpumask_andnot(housekeeping_mask,
-			       cpu_possible_mask, non_housekeeping_mask);
-
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp)) {
-			pr_warn("Housekeeping: must include one present CPU, "
+	alloc_bootmem_cpumask_var(housekeeping_mask);
+	cpumask_andnot(*housekeeping_mask,
+				   cpu_possible_mask, non_housekeeping_mask);
+
+	cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
+	if (cpumask_empty(tmp)) {
+		pr_warn("Housekeeping: must include one present CPU, "
 				"using boot CPU:%d\n", smp_processor_id());
-			__cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
-		}
-	} else {
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp))
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
-		cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask);
-		if (!cpumask_equal(tmp, housekeeping_mask)) {
-			pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
+		__cpumask_set_cpu(smp_processor_id(), *housekeeping_mask);
+		__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
+	}
+
+	/* cpus should match when both nohz_full and isolcpus
+	 * with nohz are passed into kernel
+	 */
+	if (housekeeping_flags & flags & HK_FLAG_TICK) {
+		if (!cpumask_equal(housekeeping_mask_nohz_full,
+					housekeeping_mask_isolcpus)) {
+			pr_warn("Housekeeping: nohz_full= must match isolcpus=nohz\n");
 			free_bootmem_cpumask_var(tmp);
 			free_bootmem_cpumask_var(non_housekeeping_mask);
 			return 0;
@@ -142,7 +170,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 
 	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
 
-	return housekeeping_setup(str, flags);
+	return housekeeping_setup(str, flags, &housekeeping_mask_nohz_full);
 }
 __setup("nohz_full=", housekeeping_nohz_full_setup);
 
@@ -177,6 +205,6 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	if (!flags)
 		flags |= HK_FLAG_DOMAIN;
 
-	return housekeeping_setup(str, flags);
+	return housekeeping_setup(str, flags, &housekeeping_mask_isolcpus);
 }
 __setup("isolcpus=", housekeeping_isolcpus_setup);
-- 
2.16.2