I think I've found a limitation in the badblocks implementation (block/badblocks.c), which we now also use for nvdimm badblocks.  Consider the following operations: badblocks_set(bb, 32, 1); badblocks_set(bb, 34, 1); badblocks_set(bb, 36, 1); badblocks_show will now correctly report: 32 1 34 1 36 1 Now if I do: badblocks_set(bb, 32, 12); Ideally, this should collapse all ranges into a single (32, 12).. But looks like badblocks_set only merges one set of adjacent mergeable ranges, and then returns, resulting in: 32 3 36 1 Now if I add the same (32, 12) range again, I get: 32 5 as one more set is merged. And finally after adding (32, 12) one final time, I get the expected 32 12. Neil - do you think it will be relatively straightforward to extend badblocks_set to be aware of multi-overlap ranges like above? I haven't really looked at the internals of it (I'll take a look tomorrow), but I wanted to get this out in the meantime. Thanks, -Vishal