On Fri, Feb 11, 2022 at 01:36:06PM -0600, Bob Pearson wrote: > On 2/11/22 12:43, Jason Gunthorpe wrote: > > On Tue, Feb 08, 2022 at 03:16:42PM -0600, Bob Pearson wrote: > >> Well behaved applications will free all memory allocated by multicast > >> but programs which do not clean up properly can leave behind allocated > >> memory when the rxe driver is unloaded. This patch walks the red-black > >> tree holding multicast group elements and then walks the list of attached > >> qp's freeing the mca's and finally the mcg's. > > > > How does this happen? the ib core ensures that all uobjects are > > destroyed, so if something is still in the rb tree here it means that > > an earlier uobject destruction leaked it > > > > Jason > > The mc_grp and mc_elem objects are not rdma-core uobjects. So their memory > is allocated by the rxe driver. They get created by ib_attach_mcast and destroyed > by ib_detach_mcast. If an application crashes without calling a matching > ib_detach_mcast for each attachment the driver would have leaked the memory. > This patch fixes that. The mcast attachment is affiliated with a QP, when all the QPs are destroyed, which are rdma-core objects, then all attachments should be free'd as well. That should have happened by the time things get here I would expect a simple WARN_ON that the rb tree is empty in destroy to catch any bugs. Jason
