Hi Willy,
We're seeing a case where RocksDB hangs and becomes defunct when
trying to kill the process. v4.19 succeeds and v4.20 fails. Robert was
able to bisect this to commit b15cd800682f "dax: Convert page fault
handlers to XArray".
I see some direct usage of xa_index and wonder if there are some more
pmd fixups to do?
Other thoughts?