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radix-tree: fix multiorder BUG_ON in radix_tree_insert

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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@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox
2016-05-20 17:02:23 -07:00
committed by Linus Torvalds
parent 858299544e
commit 7b60e9ad59
2 changed files with 22 additions and 4 deletions
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14
lib/radix-tree.c
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@@ -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;