From 7b60e9ad59a31dd98c2f7ef841e2882c2b0e0f3b Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 20 May 2016 17:02:23 -0700 Subject: radix-tree: fix multiorder BUG_ON in radix_tree_insert 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 Reviewed-by: Ross Zwisler Cc: Konstantin Khlebnikov Cc: Kirill Shutemov Cc: Jan Kara Cc: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'lib/radix-tree.c') diff --git a/lib/radix-tree.c b/lib/radix-tree.c index f14ada9830ca..ff460423ff4b 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 +609,13 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index, rcu_assign_pointer(*slot, item); if (node) { + unsigned offset = get_slot_offset(node, slot); 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; -- cgit v1.2.3