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The use of the VM shrinker was a bad fit for locks. Shrinking a lock requires a round trip with the server to request a null mode. The VM treats the locks like a cache, as expected, which leads to huge amounts of locks accumulating and then being shrank in bulk. This creates a huge backlog of locks making their way through the network conversation with the server that implements invalidating to a null mode and freeing. It starves other network and lock processing, possibly for minutes. This removes the VM shrinker and instead introduces an option that sets a limit on the number of idle locks. As the number of locks exceeds the count we only try to free an oldest lock at each lock call. This results in a lock freeing pace that is proportional to the allocation of new locks by callers and so is throttled by the work done while callers hold locks. It avoids the bulk shrinking of 10s of thousands of locks that we see in the field. Signed-off-by: Zach Brown <zab@versity.com>