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ksm: rename kernel_pages_allocated
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We're not implementing swapping of KSM pages in its first release;
but when that follows, "kernel_pages_allocated" will be a very poor
name for the sysfs file showing number of nodes in the stable tree:
rename that to "pages_shared" throughout.

But we already have a "pages_shared", counting those page slots
sharing the shared pages: first rename that to... "pages_sharing".

What will become of "max_kernel_pages" when the pages shared can
be swapped?  I guess it will just be removed, so keep that name.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Izik Eidus <ieidus@redhat.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Hugh Dickins authored and Linus Torvalds committed Sep 22, 2009
1 parent 339aa62 commit b402826
Showing 1 changed file with 28 additions and 29 deletions.
57 changes: 28 additions & 29 deletions mm/ksm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -150,10 +150,10 @@ static struct kmem_cache *rmap_item_cache;
static struct kmem_cache *mm_slot_cache;

/* The number of nodes in the stable tree */
static unsigned long ksm_kernel_pages_allocated;
static unsigned long ksm_pages_shared;

/* The number of page slots sharing those nodes */
static unsigned long ksm_pages_shared;
static unsigned long ksm_pages_sharing;

/* Limit on the number of unswappable pages used */
static unsigned long ksm_max_kernel_pages;
Expand Down Expand Up @@ -384,7 +384,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
next_item->address |= NODE_FLAG;
} else {
rb_erase(&rmap_item->node, &root_stable_tree);
ksm_kernel_pages_allocated--;
ksm_pages_shared--;
}
} else {
struct rmap_item *prev_item = rmap_item->prev;
Expand All @@ -398,7 +398,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
}

rmap_item->next = NULL;
ksm_pages_shared--;
ksm_pages_sharing--;

} else if (rmap_item->address & NODE_FLAG) {
unsigned char age;
Expand Down Expand Up @@ -748,7 +748,7 @@ static int try_to_merge_two_pages(struct mm_struct *mm1, unsigned long addr1,
* is the number of kernel pages that we hold.
*/
if (ksm_max_kernel_pages &&
ksm_max_kernel_pages <= ksm_kernel_pages_allocated)
ksm_max_kernel_pages <= ksm_pages_shared)
return err;

kpage = alloc_page(GFP_HIGHUSER);
Expand Down Expand Up @@ -787,7 +787,7 @@ static int try_to_merge_two_pages(struct mm_struct *mm1, unsigned long addr1,
if (err)
break_cow(mm1, addr1);
else
ksm_pages_shared += 2;
ksm_pages_sharing += 2;
}

put_page(kpage);
Expand Down Expand Up @@ -817,7 +817,7 @@ static int try_to_merge_with_ksm_page(struct mm_struct *mm1,
up_read(&mm1->mmap_sem);

if (!err)
ksm_pages_shared++;
ksm_pages_sharing++;

return err;
}
Expand Down Expand Up @@ -928,7 +928,7 @@ static struct rmap_item *stable_tree_insert(struct page *page,
}
}

ksm_kernel_pages_allocated++;
ksm_pages_shared++;

rmap_item->address |= NODE_FLAG | STABLE_FLAG;
rmap_item->next = NULL;
Expand Down Expand Up @@ -1044,7 +1044,7 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
tree_rmap_item = stable_tree_search(page, page2, rmap_item);
if (tree_rmap_item) {
if (page == page2[0]) { /* forked */
ksm_pages_shared++;
ksm_pages_sharing++;
err = 0;
} else
err = try_to_merge_with_ksm_page(rmap_item->mm,
Expand Down Expand Up @@ -1107,7 +1107,7 @@ 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_shared -= 2;
ksm_pages_sharing -= 2;
}
}

Expand Down Expand Up @@ -1423,7 +1423,7 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
/*
* KSM_RUN_MERGE sets ksmd running, and 0 stops it running.
* KSM_RUN_UNMERGE stops it running and unmerges all rmap_items,
* breaking COW to free the kernel_pages_allocated (but leaves
* breaking COW to free the unswappable pages_shared (but leaves
* mm_slots on the list for when ksmd may be set running again).
*/

Expand All @@ -1442,22 +1442,6 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
}
KSM_ATTR(run);

static ssize_t pages_shared_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%lu\n",
ksm_pages_shared - ksm_kernel_pages_allocated);
}
KSM_ATTR_RO(pages_shared);

static ssize_t kernel_pages_allocated_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%lu\n", ksm_kernel_pages_allocated);
}
KSM_ATTR_RO(kernel_pages_allocated);

static ssize_t max_kernel_pages_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
Expand All @@ -1481,13 +1465,28 @@ static ssize_t max_kernel_pages_show(struct kobject *kobj,
}
KSM_ATTR(max_kernel_pages);

static ssize_t pages_shared_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return sprintf(buf, "%lu\n", ksm_pages_shared);
}
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);
}
KSM_ATTR_RO(pages_sharing);

static struct attribute *ksm_attrs[] = {
&sleep_millisecs_attr.attr,
&pages_to_scan_attr.attr,
&run_attr.attr,
&pages_shared_attr.attr,
&kernel_pages_allocated_attr.attr,
&max_kernel_pages_attr.attr,
&pages_shared_attr.attr,
&pages_sharing_attr.attr,
NULL,
};

Expand Down

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