On Thu, Jul 25, 2019 at 10:04:58AM +0800, Ming Lei wrote: > Hi, > > When one request is dispatched to LLD via dm-rq, if the result is > BLK_STS_*RESOURCE, dm-rq will free the request. However, LLD may allocate > private data for this request, so this way will cause memory leak. > > Add .cleanup_rq() callback and implement it in SCSI for fixing the issue, > since SCSI is the only driver which allocates private requst data in > .queue_rq() path. > > Another use case of this callback is to free the request and re-submit > bios during cpu hotplug when the hctx is dead, see the following link: > > https://lore.kernel.org/linux-block/[email protected]/T/#t > > V4: > - add more commit log on the new .cleanup_rq callback, as suggested > by Mike > > V3: > - run .cleanup_rq() from dm-rq because this issue is dm-rq specific, > and even in future it should be still very unusual to free request > in this way. If we call .cleanup_rq() in generic rq free code(fast > path), cost will be introduced unnecessarily, also we have to > consider related race. > > V2: > - run .cleanup_rq() in blk_mq_free_request(), as suggested by Mike > > > > Ming Lei (2): > blk-mq: add callback of .cleanup_rq > scsi: implement .cleanup_rq callback > > drivers/md/dm-rq.c | 1 + > drivers/scsi/scsi_lib.c | 13 +++++++++++++ > include/linux/blk-mq.h | 13 +++++++++++++ > 3 files changed, 27 insertions(+) > > Cc: Ewan D. Milne <[email protected]> > Cc: Bart Van Assche <[email protected]> > Cc: Hannes Reinecke <[email protected]> > Cc: Christoph Hellwig <[email protected]> > Cc: Mike Snitzer <[email protected]> > Cc: [email protected] > Cc: <[email protected]> > Fixes: 396eaf21ee17 ("blk-mq: improve DM's blk-mq IO merging via > blk_insert_cloned_request feedback")
Hello Jens & guys, Ping on this fix. Thanks, Ming
