RHEL6: kernel BUG at net/sunrpc/svcsock.c:948 - nfsd crash in svc_tcp_clear_pages and RIP svc_tcp_sock_detach

Issue

• NFS server (nfsd) kernel BUG at net/sunrpc/svcsock.c:948 - BUG_ON in svc_tcp_clear_pages and RIP svc_tcp_sock_detach

kernel: nfsd: recvfrom returned errno 104
kernel: ------------[ cut here ]------------
kernel: kernel BUG at net/sunrpc/svcsock.c:948!
kernel: invalid opcode: 0000 [#1] SMP

• resolving the above line to source code shows the following assertion was hit: BUG_ON(svsk->sk_pages[i] == NULL);

net/sunrpc/svcsock.c
939 static void svc_tcp_clear_pages(struct svc_sock *svsk)
940 {
941     unsigned int i, len, npages;
942 
943     if (svsk->sk_tcplen <= sizeof(rpc_fraghdr))
944             goto out;
945     len = svsk->sk_tcplen - sizeof(rpc_fraghdr);
946     npages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
947     for (i = 0; i < npages; i++) {
948-->          BUG_ON(svsk->sk_pages[i] == NULL);
949             put_page(svsk->sk_pages[i]);
950             svsk->sk_pages[i] = NULL;
951     }