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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
lib/radix-tree.c
View File

@ -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)); 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. * Returns 1 if any slot in the node has this tag set.
* Otherwise returns 0. * Otherwise returns 0.
@ -604,12 +609,13 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
rcu_assign_pointer(*slot, item); rcu_assign_pointer(*slot, item);
if (node) { if (node) {
unsigned offset = get_slot_offset(node, slot);
node->count++; node->count++;
BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK)); BUG_ON(tag_get(node, 0, offset));
BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK)); BUG_ON(tag_get(node, 1, offset));
BUG_ON(tag_get(node, 2, offset));
} else { } else {
BUG_ON(root_tag_get(root, 0)); BUG_ON(root_tags_get(root));
BUG_ON(root_tag_get(root, 1));
} }
return 0; return 0;

12
tools/testing/radix-tree/multiorder.c
View File

@ -81,6 +81,17 @@ static void multiorder_shrink(unsigned long index, int order)
item_check_absent(&tree, i); 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) void multiorder_checks(void)
{ {
int i; int i;
@ -94,4 +105,5 @@ void multiorder_checks(void)
for (i = 0; i < 15; i++) for (i = 0; i < 15; i++)
multiorder_shrink((1UL << (i + RADIX_TREE_MAP_SHIFT)), i); multiorder_shrink((1UL << (i + RADIX_TREE_MAP_SHIFT)), i);
multiorder_insert_bug();
} }