mm: convert mm->cpu_vm_cpumask into cpumask_var_t
cpumask_t is very big struct and cpu_vm_mask is placed wrong position.
It might lead to reduce cache hit ratio.
This patch has two change.
1) Move the place of cpumask into last of mm_struct. Because usually cpumask
is accessed only front bits when the system has cpu-hotplug capability
2) Convert cpu_vm_mask into cpumask_var_t. It may help to reduce memory
footprint if cpumask_size() will use nr_cpumask_bits properly in future.
In addition, this patch change the name of cpu_vm_mask with cpu_vm_mask_var.
It may help to detect out of tree cpu_vm_mask users.
This patch has no functional change.
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/fork.c b/kernel/fork.c
index 9276927..8e7e135 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -485,6 +485,20 @@
#endif
}
+int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+#ifdef CONFIG_CPUMASK_OFFSTACK
+ if (!alloc_cpumask_var(&mm->cpu_vm_mask_var, GFP_KERNEL))
+ return -ENOMEM;
+
+ if (oldmm)
+ cpumask_copy(mm_cpumask(mm), mm_cpumask(oldmm));
+ else
+ memset(mm_cpumask(mm), 0, cpumask_size());
+#endif
+ return 0;
+}
+
static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
{
atomic_set(&mm->mm_users, 1);
@@ -521,10 +535,20 @@
struct mm_struct * mm;
mm = allocate_mm();
- if (mm) {
- memset(mm, 0, sizeof(*mm));
- mm = mm_init(mm, current);
+ if (!mm)
+ return NULL;
+
+ memset(mm, 0, sizeof(*mm));
+ mm = mm_init(mm, current);
+ if (!mm)
+ return NULL;
+
+ if (mm_init_cpumask(mm, NULL)) {
+ mm_free_pgd(mm);
+ free_mm(mm);
+ return NULL;
}
+
return mm;
}
@@ -536,6 +560,7 @@
void __mmdrop(struct mm_struct *mm)
{
BUG_ON(mm == &init_mm);
+ free_cpumask_var(mm->cpu_vm_mask_var);
mm_free_pgd(mm);
destroy_context(mm);
mmu_notifier_mm_destroy(mm);
@@ -690,6 +715,9 @@
if (!mm_init(mm, tsk))
goto fail_nomem;
+ if (mm_init_cpumask(mm, oldmm))
+ goto fail_nocpumask;
+
if (init_new_context(tsk, mm))
goto fail_nocontext;
@@ -716,6 +744,9 @@
return NULL;
fail_nocontext:
+ free_cpumask_var(mm->cpu_vm_mask_var);
+
+fail_nocpumask:
/*
* If init_new_context() failed, we cannot use mmput() to free the mm
* because it calls destroy_context()