These BUG_ON tests are to ensure that all the tags are clear when
inserting a new entry. If we insert a multiorder entry, we'll end up
looking at the tags for a different node, and so the BUG_ON can end up
triggering spuriously.
Also, we now have three tags, not two, so check all three are clear,
and check all the root tags with a single call to BUG_ON since the bits
are stored contiguously.
Include a test-case to ensure this problem does not reoccur.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
lib/radix-tree.c | 16 ++++++++++++----
tools/testing/radix-tree/multiorder.c | 13 +++++++++++++
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 2ca2b416b476..33f91f207587 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -165,6 +165,11 @@ static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
}
+static inline unsigned root_tags_get(struct radix_tree_root *root)
+{
+ return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT;
+}
+
/*
* Returns 1 if any slot in the node has this tag set.
* Otherwise returns 0.
@@ -604,12 +609,15 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
rcu_assign_pointer(*slot, item);
if (node) {
+ unsigned shift = ((node->path - 1) & RADIX_TREE_HEIGHT_MASK) *
+ RADIX_TREE_MAP_SHIFT;
+ unsigned offset = (index >> shift) & RADIX_TREE_MAP_MASK;
node->count++;
- BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
- BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
+ BUG_ON(tag_get(node, 0, offset));
+ BUG_ON(tag_get(node, 1, offset));
+ BUG_ON(tag_get(node, 2, offset));
} else {
- BUG_ON(root_tag_get(root, 0));
- BUG_ON(root_tag_get(root, 1));
+ BUG_ON(root_tags_get(root));
}
return 0;
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index cfe718c78eb6..606bfe04b104 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -46,6 +46,17 @@ static void multiorder_check(unsigned long index, int order)
item_check_absent(&tree, i);
}
+static void multiorder_insert_bug(void)
+{
+ RADIX_TREE(tree, GFP_KERNEL);
+
+ item_insert(&tree, 0);
+ radix_tree_tag_set(&tree, 0, 0);
+ item_insert_order(&tree, 3 << 6, 6);
+
+ item_kill_tree(&tree);
+}
+
void multiorder_checks(void)
{
int i;
@@ -55,4 +66,6 @@ void multiorder_checks(void)
multiorder_check(0, i);
multiorder_check((1UL << i) + 1, i);
}
+
+ multiorder_insert_bug();
}
--
2.8.0.rc3
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