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-rw-r--r--kernel/mm/ksm.c49
1 files changed, 35 insertions, 14 deletions
diff --git a/kernel/mm/ksm.c b/kernel/mm/ksm.c
index 7ee101eaa..b5cd647da 100644
--- a/kernel/mm/ksm.c
+++ b/kernel/mm/ksm.c
@@ -475,7 +475,8 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
flush_dcache_page(page);
} else {
put_page(page);
-out: page = NULL;
+out:
+ page = NULL;
}
up_read(&mm->mmap_sem);
return page;
@@ -625,7 +626,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
unlock_page(page);
put_page(page);
- if (stable_node->hlist.first)
+ if (!hlist_empty(&stable_node->hlist))
ksm_pages_sharing--;
else
ksm_pages_shared--;
@@ -1021,8 +1022,6 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
if (page == kpage) /* ksm page forked */
return 0;
- if (!(vma->vm_flags & VM_MERGEABLE))
- goto out;
if (PageTransCompound(page) && page_trans_compound_anon_split(page))
goto out;
BUG_ON(PageTransCompound(page));
@@ -1087,10 +1086,8 @@ static int try_to_merge_with_ksm_page(struct rmap_item *rmap_item,
int err = -EFAULT;
down_read(&mm->mmap_sem);
- if (ksm_test_exit(mm))
- goto out;
- vma = find_vma(mm, rmap_item->address);
- if (!vma || vma->vm_start > rmap_item->address)
+ vma = find_mergeable_vma(mm, rmap_item->address);
+ if (!vma)
goto out;
err = try_to_merge_one_page(vma, page, kpage);
@@ -1177,8 +1174,18 @@ again:
cond_resched();
stable_node = rb_entry(*new, struct stable_node, node);
tree_page = get_ksm_page(stable_node, false);
- if (!tree_page)
- return NULL;
+ if (!tree_page) {
+ /*
+ * If we walked over a stale stable_node,
+ * get_ksm_page() will call rb_erase() and it
+ * may rebalance the tree from under us. So
+ * restart the search from scratch. Returning
+ * NULL would be safe too, but we'd generate
+ * false negative insertions just because some
+ * stable_node was stale.
+ */
+ goto again;
+ }
ret = memcmp_pages(page, tree_page);
put_page(tree_page);
@@ -1254,12 +1261,14 @@ static struct stable_node *stable_tree_insert(struct page *kpage)
unsigned long kpfn;
struct rb_root *root;
struct rb_node **new;
- struct rb_node *parent = NULL;
+ struct rb_node *parent;
struct stable_node *stable_node;
kpfn = page_to_pfn(kpage);
nid = get_kpfn_nid(kpfn);
root = root_stable_tree + nid;
+again:
+ parent = NULL;
new = &root->rb_node;
while (*new) {
@@ -1269,8 +1278,18 @@ static struct stable_node *stable_tree_insert(struct page *kpage)
cond_resched();
stable_node = rb_entry(*new, struct stable_node, node);
tree_page = get_ksm_page(stable_node, false);
- if (!tree_page)
- return NULL;
+ if (!tree_page) {
+ /*
+ * If we walked over a stale stable_node,
+ * get_ksm_page() will call rb_erase() and it
+ * may rebalance the tree from under us. So
+ * restart the search from scratch. Returning
+ * NULL would be safe too, but we'd generate
+ * false negative insertions just because some
+ * stable_node was stale.
+ */
+ goto again;
+ }
ret = memcmp_pages(kpage, tree_page);
put_page(tree_page);
@@ -1340,7 +1359,7 @@ struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item,
cond_resched();
tree_rmap_item = rb_entry(*new, struct rmap_item, node);
tree_page = get_mergeable_page(tree_rmap_item);
- if (IS_ERR_OR_NULL(tree_page))
+ if (!tree_page)
return NULL;
/*
@@ -1914,9 +1933,11 @@ again:
struct anon_vma_chain *vmac;
struct vm_area_struct *vma;
+ cond_resched();
anon_vma_lock_read(anon_vma);
anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
0, ULONG_MAX) {
+ cond_resched();
vma = vmac->vma;
if (rmap_item->address < vma->vm_start ||
rmap_item->address >= vma->vm_end)