I've found that Trond fixed it recently in commit 875f0706acc "SUNRPC: The TCP back channel mustn't disappear while requests are outstanding" On 11/29/19 5:10 PM, Vasily Averin wrote:
OpenVz team got complain on crash in bc_svc_process(). Crashed node had 15 running containers with active nfsv4.1 mounts, single nfsv4.1-svc thread was processed its back-channel requests. In our case nfs41_callback_svc() took rpc_rqst *req from serv->sv_cb_list started its processing but found that req->rq_xprt points to already freed struct rpc_xprt aka part of struct sock_xprt transport. Back-channel request was submitted via xprt_complete_bc_request(), its processing uses req->rq_xprt reference in many times, however I did not found who keeps this reference. It seems sock_xprt or even whole its net namespace can be freed before bc_svc_process() will start processing of submitted back-channel request, and req->rq_xprt using is unsafe in bc_svc_process() Am I missed something probably?
