From: xu xin <xu.xin16@xxxxxxxxxx>
A new function try_to_get_old_rmap_item is abstracted from
get_next_rmap_item. This function will be reused by the subsequent
patches about counting ksm_zero_pages.
The patch improves the readability and reusability of KSM code.
Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: Xuexin Jiang <jiang.xuexin@xxxxxxxxxx>
Reviewed-by: Xiaokai Ran <ran.xiaokai@xxxxxxxxxx>
Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx>
v5->v6:
Modify some comments according to David's suggestions.
---
mm/ksm.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c
index 83e2f74ae7da..905a79d213da 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2214,23 +2214,38 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
}
}
-static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot,
- struct ksm_rmap_item **rmap_list,
- unsigned long addr)
+static struct ksm_rmap_item *try_to_get_old_rmap_item(unsigned long addr,
+ struct ksm_rmap_item **rmap_list)
{
- struct ksm_rmap_item *rmap_item;
-
while (*rmap_list) {
- rmap_item = *rmap_list;
+ struct ksm_rmap_item *rmap_item = *rmap_list;
+
if ((rmap_item->address & PAGE_MASK) == addr)
return rmap_item;
if (rmap_item->address > addr)
break;
*rmap_list = rmap_item->rmap_list;
+ /*
+ * If we end up here, the VMA is MADV_UNMERGEABLE or its page
+ * is ineligible or discarded, e.g. MADV_DONTNEED.
+ */
remove_rmap_item_from_tree(rmap_item);
free_rmap_item(rmap_item);
}
+ return NULL;
+}
+
+static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot,
+ struct ksm_rmap_item **rmap_list,
+ unsigned long addr)
+{
+ struct ksm_rmap_item *rmap_item;
+
+ rmap_item = try_to_get_old_rmap_item(addr, rmap_list);
+ if (rmap_item)
+ return rmap_item;
+
rmap_item = alloc_rmap_item();
if (rmap_item) {
/* It has already been zeroed */
--
2.15.2
