The issue is very reproducible. Just takes a few hours. If there is any debug info you would like turned on, I'd be glad to enable it and re-run the test. The test workload that causes this: Concurrent access from multiple threads. 1 thread continuously (in a loop) running python os.walk (i.e., readdir) of the entire filesystem, roughly ~5M files total. 5 more threads are writing a few thousand files each. When the writes complete, a single thread verifies written content, then deletes it. Then the writes repeat again. I did see about 97,000 of the following messages in a few minutes of enabling debug: LogDebugAlt(COMPONENT_NFS_READDIR, COMPONENT_CACHE_INODE, "Already existent when inserting new dirent on entry=%p name=%s", entry, v->name); LogFullDebugAlt(COMPONENT_NFS_READDIR, COMPONENT_CACHE_INODE, "Duplicate insert of %s v->chunk=%p v2->chunk=%p", v->name, v->chunk, v2->chunk);