Re: [RFC][PATCH 0/1] Node-based reclaim/migration

KAMEZAWA Hiroyuki
2006-12-01T03:10:55Z

On Thu, 30 Nov 2006 18:44:30 -0800 (PST)
Christoph Lameter <clameter@sgi.com> wrote:

> Fixed up patch with more comments and a check that the migration_count is
> zero before freeing.
>

Looks good, thanks. we need users and tests :)
-Kame

> Index: linux-2.6.19-rc6-mm2/include/linux/rmap.h
> ===================================================================
> --- linux-2.6.19-rc6-mm2.orig/include/linux/rmap.h 2006-11-15 22:03:40.000000000 -0600
> +++ linux-2.6.19-rc6-mm2/include/linux/rmap.h 2006-11-30 17:39:17.643728656 -0600
> @@ -26,6 +26,7 @@
> struct anon_vma {
> spinlock_t lock; /* Serialize access to vma list */
> struct list_head head; /* List of private "related" vmas */
> + int migration_count; /* # processes migrating pages */
> };
>
> #ifdef CONFIG_MMU
> Index: linux-2.6.19-rc6-mm2/mm/migrate.c
> ===================================================================
> --- linux-2.6.19-rc6-mm2.orig/mm/migrate.c 2006-11-29 18:37:17.797934398 -0600
> +++ linux-2.6.19-rc6-mm2/mm/migrate.c 2006-11-30 20:41:13.810836561 -0600
> @@ -209,15 +209,12 @@ static void remove_file_migration_ptes(s
> spin_unlock(&mapping->i_mmap_lock);
> }
>
> -/*
> - * Must hold mmap_sem lock on at least one of the vmas containing
> - * the page so that the anon_vma cannot vanish.
> - */
> static void remove_anon_migration_ptes(struct page *old, struct page *new)
> {
> struct anon_vma *anon_vma;
> struct vm_area_struct *vma;
> unsigned long mapping;
> + int empty;
>
> mapping = (unsigned long)new->mapping;
>
> @@ -225,15 +222,20 @@ static void remove_anon_migration_ptes(s
> return;
>
> /*
> - * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
> + * We have increased migration_count So no need to call
> + * page_lock_anon_vma.
> */
> anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
> spin_lock(&anon_vma->lock);
> + anon_vma->migration_count--;
>
> list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
> remove_migration_pte(vma, old, new);
>
> + empty = list_empty(&anon_vma->head) && !anon_vma->migration_count;
> spin_unlock(&anon_vma->lock);
> + if (empty)
> + anon_vma_free(anon_vma);
> }
>
> /*
> Index: linux-2.6.19-rc6-mm2/mm/rmap.c
> ===================================================================
> --- linux-2.6.19-rc6-mm2.orig/mm/rmap.c 2006-11-15 22:03:40.000000000 -0600
> +++ linux-2.6.19-rc6-mm2/mm/rmap.c 2006-11-30 20:39:52.266554217 -0600
> @@ -150,8 +150,8 @@ void anon_vma_unlink(struct vm_area_stru
> validate_anon_vma(vma);
> list_del(&vma->anon_vma_node);
>
> - /* We must garbage collect the anon_vma if it's empty */
> - empty = list_empty(&anon_vma->head);
> + /* We must garbage collect the anon_vma if it's unused */
> + empty = list_empty(&anon_vma->head) && !anon_vma->migration_count;
> spin_unlock(&anon_vma->lock);
>
> if (empty)
> @@ -787,6 +787,10 @@ static int try_to_unmap_anon(struct page
> if (!anon_vma)
> return ret;
>
> + if (migration)
> + /* Prevent freeing while migrating pages */
> + anon_vma->migration_count++;
> +
> list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
> ret = try_to_unmap_one(page, vma, migration);
> if (ret == SWAP_FAIL || !page_mapped(page))