Re: [PATCH -next] SUNRPC: Clean XPRT_CONGESTED of xprt->state when rpc task is killed
From: Trond Myklebust
Date: Mon Dec 20 2021 - 13:22:46 EST
On Mon, 2021-12-20 at 11:39 +0800, Bixuan Cui wrote:
> ping~
>
> 在 2021/12/14 下午9:53, Bixuan Cui 写道:
> > When the values of tcp_max_slot_table_entries and
> > sunrpc.tcp_slot_table_entries are lower than the number of rpc
> > tasks,
> > xprt_dynamic_alloc_slot() in xprt_alloc_slot() will return -EAGAIN,
> > and
> > then set xprt->state to XPRT_CONGESTED:
> > xprt_retry_reserve
> > ->xprt_do_reserve
> > ->xprt_alloc_slot
> > ->xprt_dynamic_alloc_slot // return -EAGAIN and task-
> > >tk_rqstp is NULL
> > ->xprt_add_backlog // set_bit(XPRT_CONGESTED, &xprt-
> > >state);
> >
> > When rpc task is killed, XPRT_CONGESTED bit of xprt->state will not
> > be
> > cleaned up and nfs hangs:
> > rpc_exit_task
> > ->xprt_release // if (req == NULL) is true, then
> > XPRT_CONGESTED
> > // bit not clean
> >
> > Add xprt_wake_up_backlog(xprt) to clean XPRT_CONGESTED bit in
> > xprt_release().
I'm not seeing how this explanation makes sense. If the task doesn't
hold a slot, then freeing that task isn't going to clear the congestion
caused by all the slots being in use.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx