No but two things occur which are bad
1. The request queue gets filled unfairly by the one task because
there's a lack of request fairness (its not normally an issue)
2. The queue fills and blocks other drivers up because Linus still
hasnt included the patch that was developed to keep a per
device queue (SCSI doesnt have this problem as it empties the
request queues onto its own queues), but stuff like IDE and
especially slower devices - eg floppies are dire for it.
(and yes Linus can we please have the multiple queues patch in
2.2 pending the new io_request stuff in 2.3...)
Alan