On Fri, Jul 26, 2019 at 06:20:46PM +0200, Benjamin Block wrote: > Hey Ming Lei, > > On Sat, Jul 20, 2019 at 11:06:35AM +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. > > I am confused about this. Probably because I am not up-to-date with > all of blk-mq. But if you free the LLD private data before the request > is finished, what is the LLD doing if the request finishes afterwards? > Would that not be an automatic use-after-free? Wrt. this special use case, the underlying request is totally covered by dm-rq after .queue_rq() returns BLK_STS_*RESOURCE. So the request won't be re-dispatched by blk-mq at all. thanks, Ming
