This is where the mm_autonuma structure is being handled.
mm_autonuma holds the link for knuma_scand's list of mm structures to
scan and a pointer to the associated mm structure for knuma_scand's
convenience.
It also contains the per-mm NUMA statistics collected by knuma_scand
daemon. The per-mm NUMA statistics are needed by
sched_autonuma_balance to take appropriate NUMA balancing decision
when balancing threads belonging to different processes.
Just like task_autonuma, this is only allocated at runtime if the
hardware the kernel is running on has been detected as NUMA. On not
NUMA hardware the memory cost is reduced to one pointer per mm.
To get rid of the pointer in the each mm, the kernel can be compiled
with CONFIG_AUTONUMA=n.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
kernel/fork.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index 9ba6e9b..7367c32 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -532,6 +532,8 @@ static void mm_init_aio(struct mm_struct *mm)
static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
{
+ if (unlikely(alloc_mm_autonuma(mm)))
+ goto out_free_mm;
atomic_set(&mm->mm_users, 1);
atomic_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);
@@ -554,6 +556,8 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
return mm;
}
+ free_mm_autonuma(mm);
+out_free_mm:
free_mm(mm);
return NULL;
}
@@ -603,6 +607,7 @@ void __mmdrop(struct mm_struct *mm)
destroy_context(mm);
mmu_notifier_mm_destroy(mm);
check_mm(mm);
+ free_mm_autonuma(mm);
free_mm(mm);
}
EXPORT_SYMBOL_GPL(__mmdrop);
@@ -885,6 +890,7 @@ fail_nocontext:
* If init_new_context() failed, we cannot use mmput() to free the mm
* because it calls destroy_context()
*/
+ free_mm_autonuma(mm);
mm_free_pgd(mm);
free_mm(mm);
return NULL;
@@ -1707,6 +1713,7 @@ void __init proc_caches_init(void)
mm_cachep = kmem_cache_create("mm_struct",
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
+ mm_autonuma_init();
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
mmap_init();
nsproxy_cache_init();
--
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