On Wed, 2020-04-01 at 15:37 -0400, Chuck Lever wrote:
> If an RPC task is signaled while it is running and the transport is
> not connected, it will never sleep and never be terminated. This can
> happen when a RPC transport is shut down: the remaining tasks are
> signalled, but the transport is disconnected.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> net/sunrpc/sched.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> Interested in comments and suggestions.
>
> Nearly every time my NFS/RDMA client unmounts when using krb5, the
> umount hangs (killably). I tracked it down to an NFSv3 NULL request
> that is signalled but loops and does not exit.
>
>
> diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
> index 55e900255b0c..905c31f75593 100644
> --- a/net/sunrpc/sched.c
> +++ b/net/sunrpc/sched.c
> @@ -905,6 +905,12 @@ static void __rpc_execute(struct rpc_task *task)
> trace_rpc_task_run_action(task, do_action);
> do_action(task);
>
> + if (RPC_SIGNALLED(task)) {
> + task->tk_rpc_status = -ERESTARTSYS;
> + rpc_exit(task, -ERESTARTSYS);
> + break;
> + }
> +
Hmm... I'd really prefer to avoid this kind of check in the tight loop.
Why is this NULL request looping?
> /*
> * Lockless check for whether task is sleeping or not.
> */
> @@ -912,14 +918,6 @@ static void __rpc_execute(struct rpc_task *task)
> continue;
>
> /*
> - * Signalled tasks should exit rather than sleep.
> - */
> - if (RPC_SIGNALLED(task)) {
> - task->tk_rpc_status = -ERESTARTSYS;
> - rpc_exit(task, -ERESTARTSYS);
> - }
> -
> - /*
> * The queue->lock protects against races with
> * rpc_make_runnable().
> *
>
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
