On Mon, 2016-10-24 at 11:19 -0400, Jeff Layton wrote: > On Mon, 2016-10-24 at 09:51 -0400, Chuck Lever wrote: > > > > > > > > > > > On Oct 24, 2016, at 9:31 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > > > > On Mon, 2016-10-24 at 11:15 +0800, Eryu Guan wrote: > > > > > > > > > > > > On Sun, Oct 23, 2016 at 02:21:15PM -0400, J. Bruce Fields wrote: > > > > > > > > > > > > > > > > > > > > I'm getting an intermittent crash in the nfs server as of > > > > > 68778945e46f143ed7974b427a8065f69a4ce944 "SUNRPC: Separate buffer > > > > > pointers for RPC Call and Reply messages". > > > > > > > > > > I haven't tried to understand that commit or why it would be a problem yet, I > > > > > don't see an obvious connection--I can take a closer look Monday. > > > > > > > > > > Could even be that I just landed on this commit by chance, the problem is a > > > > > little hard to reproduce so I don't completely trust my testing. > > > > > > > > I've hit the same crash on 4.9-rc1 kernel, and it's reproduced for me > > > > reliably by running xfstests generic/013 case, on a loopback mounted > > > > NFSv4.1 (or NFSv4.2), XFS is the underlying exported fs. More details > > > > please see > > > > > > > > http://marc.info/?l=linux-nfs&m=147714320129362&w=2 > > > > > > > > > > Looks like you landed at the same commit as Bruce, so that's probably > > > legit. That commit is very small though. The only real change that > > > doesn't affect the new field is this: > > > > > > > > > @@ -1766,7 +1766,7 @@ rpc_xdr_encode(struct rpc_task *task) > > > req->rq_buffer, > > > req->rq_callsize); > > > xdr_buf_init(&req->rq_rcv_buf, > > > - (char *)req->rq_buffer + req->rq_callsize, > > > + req->rq_rbuffer, > > > req->rq_rcvsize); > > > > > > > > > So I'm guessing this is breaking the callback channel somehow? > > > > Could be the TCP backchannel code is using rq_buffer in a different > > way than RDMA backchannel or the forward channel code. > > > > Well, it basically allocates a page per rpc_rqst and then maps that. > > One thing I notice is that this patch ensures that rq_rbuffer gets set > up in rpc_malloc and xprt_rdma_allocate, but it looks like > xprt_alloc_bc_req didn't get the same treatment. > > I suspect that that may be the problem... > In fact, maybe we just need this here? (untested and probably whitespace damaged): diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c index ac701c28f44f..c561aa8ce05b 100644 --- a/net/sunrpc/backchannel_rqst.c +++ b/net/sunrpc/backchannel_rqst.c @@ -100,6 +100,7 @@ struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags) goto out_free; } req->rq_rcv_buf.len = PAGE_SIZE; + req->rq_rbuffer = req->rq_rcv_buf.head[0].iov_base; /* Preallocate one XDR send buffer */ if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) { -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
