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