It's in fuse_parse_cache(). %rbx (ffff88859367bff0) is fuse_dirent
pointer - addr + offset. FUSE_DIRENT_SIZE() is trying to dereference
namelen off of it but that derefs into the next page which is disabled
by pagealloc debug causing a PF.
This is caused by dirent->namelen being accessed before ensuring that
there's enough bytes in the page for the dirent. Fix it by pushing
down reclen calculation.