Here is a simple patch to use a per cpu cpumask instead of constructing
one on the stack. I have been running awhile with this one:
Do not use stack to allocate cpumask for cpumask_of_cpu
Signed-off-by: Christoph Lameter <[email protected]>
Modified to be used only if NR_CPUS is greater than the BITS_PER_LONG
as well as fix cases where !SMP and both NR_CPUS > and < BITS_PER_LONG.
Signed-off-by: Mike Travis <[email protected]>
---
arch/x86/kernel/process_64.c | 1 +
arch/x86/mm/numa_64.c | 1 +
include/linux/cpumask.h | 4 ++++
include/linux/sched.h | 4 ++++
kernel/sched.c | 9 +++++++++
5 files changed, 19 insertions(+)
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -222,6 +222,9 @@ int __next_cpu(int n, const cpumask_t *s
#define next_cpu(n, src) 1
#endif
+#if defined(CONFIG_SMP) && (NR_CPUS > BITS_PER_LONG)
+#define cpumask_of_cpu(cpu) per_cpu(cpu_mask, cpu)
+#else
#define cpumask_of_cpu(cpu) \
({ \
typeof(_unused_cpumask_arg_) m; \
@@ -233,6 +236,7 @@ int __next_cpu(int n, const cpumask_t *s
} \
m; \
})
+#endif
#define CPU_MASK_LAST_WORD BITMAP_LAST_WORD_MASK(NR_CPUS)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6732,6 +6732,11 @@ static void init_cfs_rq(struct cfs_rq *c
cfs_rq->min_vruntime = (u64)(-(1LL << 20));
}
+#if NR_CPUS > BITS_PER_LONG
+DEFINE_PER_CPU(cpumask_t, cpu_mask);
+EXPORT_PER_CPU_SYMBOL(cpu_mask);
+#endif
+
void __init sched_init(void)
{
int highest_cpu = 0;
@@ -6741,6 +6746,10 @@ void __init sched_init(void)
struct rt_prio_array *array;
struct rq *rq;
+#if NR_CPUS > BITS_PER_LONG
+ /* This makes cpumask_of_cpu work */
+ cpu_set(i, per_cpu(cpu_mask, i));
+#endif
rq = cpu_rq(i);
spin_lock_init(&rq->lock);
lockdep_set_class(&rq->lock, &rq->rq_lock_key);
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -36,6 +36,7 @@
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/tick.h>
+#include <linux/percpu.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -11,6 +11,7 @@
#include <linux/ctype.h>
#include <linux/module.h>
#include <linux/nodemask.h>
+#include <linux/sched.h>
#include <asm/e820.h>
#include <asm/proto.h>
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2024,6 +2024,10 @@ static inline void migration_init(void)
#define TASK_SIZE_OF(tsk) TASK_SIZE
#endif
+#if defined(CONFIG_SMP) && (NR_CPUS > BITS_PER_LONG)
+DECLARE_PER_CPU(cpumask_t, cpu_mask);
+#endif
+
#endif /* __KERNEL__ */
#endif
--
-
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