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Commit 7b60e9ad authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
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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: default avatarMatthew Wilcox <willy@linux.intel.com>
Reviewed-by: default avatarRoss 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 85829954

lib/radix-tree.c

+10 −4
Original line number Diff line number Diff line
@@ -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;

tools/testing/radix-tree/multiorder.c

+12 −0
Original line number Diff line number Diff line
@@ -81,6 +81,17 @@ static void multiorder_shrink(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;
@@ -94,4 +105,5 @@ void multiorder_checks(void) 
	for (i = 0; i < 15; i++)

		multiorder_shrink((1UL << (i + RADIX_TREE_MAP_SHIFT)), i);



	multiorder_insert_bug();

}