Commit e178dfde authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

ksm: move pages_sharing updates 



The pages_shared count is incremented and decremented when adding a node
to and removing a node from the stable tree: easy to understand.  But the
pages_sharing count was hard to follow, being adjusted in various places:
increment and decrement it when adding to and removing from the stable tree.

And the pages_sharing variable used to include the pages_shared, then those
were subtracted when shown in the pages_sharing sysfs file: now keep it as
an exclusive count of leaves hanging off the stable tree nodes, throughout.

Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: default avatarIzik Eidus <ieidus@redhat.com>
Acked-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b4028260

mm/ksm.c

+9 −15
Original line number Diff line number Diff line
@@ -152,7 +152,7 @@ static struct kmem_cache *mm_slot_cache; 
/* The number of nodes in the stable tree */

static unsigned long ksm_pages_shared;



/* The number of page slots sharing those nodes */

/* The number of page slots additionally sharing those nodes */

static unsigned long ksm_pages_sharing;



/* Limit on the number of unswappable pages used */
@@ -382,6 +382,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) 
						&next_item->node,

						&root_stable_tree);

				next_item->address |= NODE_FLAG;

				ksm_pages_sharing--;

			} else {

				rb_erase(&rmap_item->node, &root_stable_tree);

				ksm_pages_shared--;
@@ -395,10 +396,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item) 
				BUG_ON(next_item->prev != rmap_item);

				next_item->prev = rmap_item->prev;

			}

			ksm_pages_sharing--;

		}



		rmap_item->next = NULL;

		ksm_pages_sharing--;



	} else if (rmap_item->address & NODE_FLAG) {

		unsigned char age;
@@ -786,8 +787,6 @@ static int try_to_merge_two_pages(struct mm_struct *mm1, unsigned long addr1, 
		 */

		if (err)

			break_cow(mm1, addr1);

		else

			ksm_pages_sharing += 2;

	}



	put_page(kpage);
@@ -816,9 +815,6 @@ static int try_to_merge_with_ksm_page(struct mm_struct *mm1, 
	err = try_to_merge_one_page(vma, page1, kpage);

	up_read(&mm1->mmap_sem);



	if (!err)

		ksm_pages_sharing++;



	return err;

}
@@ -928,13 +924,12 @@ static struct rmap_item *stable_tree_insert(struct page *page, 
		}

	}



	ksm_pages_shared++;



	rmap_item->address |= NODE_FLAG | STABLE_FLAG;

	rmap_item->next = NULL;

	rb_link_node(&rmap_item->node, parent, new);

	rb_insert_color(&rmap_item->node, &root_stable_tree);



	ksm_pages_shared++;

	return rmap_item;

}
@@ -1019,6 +1014,8 @@ static void stable_tree_append(struct rmap_item *rmap_item, 


	tree_rmap_item->next = rmap_item;

	rmap_item->address |= STABLE_FLAG;



	ksm_pages_sharing++;

}



/*
@@ -1043,10 +1040,9 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) 
	/* We first start with searching the page inside the stable tree */

	tree_rmap_item = stable_tree_search(page, page2, rmap_item);

	if (tree_rmap_item) {

		if (page == page2[0]) {			/* forked */

			ksm_pages_sharing++;

		if (page == page2[0])			/* forked */

			err = 0;

		} else

		else

			err = try_to_merge_with_ksm_page(rmap_item->mm,

							 rmap_item->address,

							 page, page2[0]);
@@ -1107,7 +1103,6 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item) 
				break_cow(tree_rmap_item->mm,

						tree_rmap_item->address);

				break_cow(rmap_item->mm, rmap_item->address);

				ksm_pages_sharing -= 2;

			}

		}
@@ -1475,8 +1470,7 @@ KSM_ATTR_RO(pages_shared); 
static ssize_t pages_sharing_show(struct kobject *kobj,

				  struct kobj_attribute *attr, char *buf)

{

	return sprintf(buf, "%lu\n",

			ksm_pages_sharing - ksm_pages_shared);

	return sprintf(buf, "%lu\n", ksm_pages_sharing);

}

KSM_ATTR_RO(pages_sharing);

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