++ /*
++ * A guest reaching this cutoff is dirtying lots of RAM. It should be
++ * large enough so that the guest can't dirty this much between the
++ * check and the guest actually being stopped, but it should be small
++ * enough to avoid long downtimes for non-hibernation snapshots.
++ */
++ maxlen = blk_getlength(snap_state.target) - 100*1024*1024;