Re: [REGRESSION] funny sched_domain build failure during resume

Peter Zijlstra
2014-05-16T10:43:44Z

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OK I made that..

---

Subject: sched/cpudl: Replace NR_CPUS arrays
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed May 14 16:13:56 CEST 2014

Tejun reported that his resume was failing due to order-3 allocations
from sched_domain building.

Replace the NR_CPUS arrays in there with a dynamically allocated
array.

Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
kernel/sched/cpudeadline.c | 33 ++++++++++++++++++++++++---------
kernel/sched/cpudeadline.h | 6 +++---
2 files changed, 27 insertions(+), 12 deletions(-)

--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -13,6 +13,7 @@

#include <linux/gfp.h>
#include <linux/kernel.h>
+#include <linux/slab.h>
#include "cpudeadline.h"

static inline int parent(int i)
@@ -39,8 +40,10 @@ static void cpudl_exchange(struct cpudl
{
int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;

- swap(cp->elements[a], cp->elements[b]);
- swap(cp->cpu_to_idx[cpu_a], cp->cpu_to_idx[cpu_b]);
+ swap(cp->elements[a].cpu, cp->elements[b].cpu);
+ swap(cp->elements[a].dl , cp->elements[b].dl );
+
+ swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx);
}

static void cpudl_heapify(struct cpudl *cp, int idx)
@@ -140,7 +143,7 @@ void cpudl_set(struct cpudl *cp, int cpu
WARN_ON(!cpu_present(cpu));

raw_spin_lock_irqsave(&cp->lock, flags);
- old_idx = cp->cpu_to_idx[cpu];
+ old_idx = cp->elements[cpu].idx;
if (!is_valid) {
/* remove item */
if (old_idx == IDX_INVALID) {
@@ -155,8 +158,8 @@ void cpudl_set(struct cpudl *cp, int cpu
cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
cp->elements[old_idx].cpu = new_cpu;
cp->size--;
- cp->cpu_to_idx[new_cpu] = old_idx;
- cp->cpu_to_idx[cpu] = IDX_INVALID;
+ cp->elements[new_cpu].idx = old_idx;
+ cp->elements[cpu].idx = IDX_INVALID;
while (old_idx > 0 && dl_time_before(
cp->elements[parent(old_idx)].dl,
cp->elements[old_idx].dl)) {
@@ -173,7 +176,7 @@ void cpudl_set(struct cpudl *cp, int cpu
cp->size++;
cp->elements[cp->size - 1].dl = 0;
cp->elements[cp->size - 1].cpu = cpu;
- cp->cpu_to_idx[cpu] = cp->size - 1;
+ cp->elements[cpu].idx = cp->size - 1;
cpudl_change_key(cp, cp->size - 1, dl);
cpumask_clear_cpu(cpu, cp->free_cpus);
} else {
@@ -195,10 +198,21 @@ int cpudl_init(struct cpudl *cp)
memset(cp, 0, sizeof(*cp));
raw_spin_lock_init(&cp->lock);
cp->size = 0;
- for (i = 0; i < NR_CPUS; i++)
- cp->cpu_to_idx[i] = IDX_INVALID;
- if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL))
+
+ cp->elements = kcalloc(nr_cpu_ids,
+ sizeof(struct cpudl_item),
+ GFP_KERNEL);
+ if (!cp->elements)
+ return -ENOMEM;
+
+ if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
+ kfree(cp->elements);
return -ENOMEM;
+ }
+
+ for_each_possible_cpu(i)
+ cp->elements[i].idx = IDX_INVALID;
+
cpumask_setall(cp->free_cpus);

return 0;
@@ -211,4 +225,5 @@ int cpudl_init(struct cpudl *cp)
void cpudl_cleanup(struct cpudl *cp)
{
free_cpumask_var(cp->free_cpus);
+ kfree(cp->elements);
}
--- a/kernel/sched/cpudeadline.h
+++ b/kernel/sched/cpudeadline.h
@@ -5,17 +5,17 @@

#define IDX_INVALID -1

-struct array_item {
+struct cpudl_item {
u64 dl;
int cpu;
+ int idx;
};

struct cpudl {
raw_spinlock_t lock;
int size;
- int cpu_to_idx[NR_CPUS];
- struct array_item elements[NR_CPUS];
cpumask_var_t free_cpus;
+ struct cpudl_item *elements;
};