On Mar 12, 2014, at 10:28, Jeffrey Layton <jlayton@xxxxxxxxxx> wrote: > On Wed, 12 Mar 2014 10:05:24 -0400 > Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote: > >> >> On Mar 12, 2014, at 9:33, Jeff Layton <jlayton@xxxxxxxxxx> wrote: >> >>> On Sat, 08 Mar 2014 14:13:44 -0600 >>> Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx> wrote: >>> >>>> On 3/8/2014 1:20 PM, Steve Wise wrote: >>>>> >>>>>> I removed your change and started debugging original crash that >>>>>> happens on top-o-tree. Seems like rq_next_pages is screwed >>>>>> up. It should always be >= rq_respages, yes? I added a >>>>>> BUG_ON() to assert this in rdma_read_xdr() we hit the BUG_ON(). >>>>>> Look >>>>>> >>>>>> crash> svc_rqst.rq_next_page 0xffff8800b84e6000 >>>>>> rq_next_page = 0xffff8800b84e6228 >>>>>> crash> svc_rqst.rq_respages 0xffff8800b84e6000 >>>>>> rq_respages = 0xffff8800b84e62a8 >>>>>> >>>>>> Any ideas Bruce/Tom? >>>>>> >>>>> >>>>> Guys, the patch below seems to fix the problem. Dunno if it is >>>>> correct though. What do you think? >>>>> >>>>> diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >>>>> b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >>>>> index 0ce7552..6d62411 100644 >>>>> --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >>>>> +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >>>>> @@ -90,6 +90,7 @@ static void rdma_build_arg_xdr(struct svc_rqst >>>>> *rqstp, sge_no++; >>>>> } >>>>> rqstp->rq_respages = &rqstp->rq_pages[sge_no]; >>>>> + rqstp->rq_next_page = rqstp->rq_respages; >>>>> >>>>> /* We should never run out of SGE because the limit is >>>>> defined to >>>>> * support the max allowed RPC data length >>>>> @@ -276,6 +277,7 @@ static int fast_reg_read_chunks(struct >>>>> svcxprt_rdma *xprt, >>>>> >>>>> /* rq_respages points one past arg pages */ >>>>> rqstp->rq_respages = &rqstp->rq_arg.pages[page_no]; >>>>> + rqstp->rq_next_page = rqstp->rq_respages; >>>>> >>>>> /* Create the reply and chunk maps */ >>>>> offset = 0; >>>>> >>>>> >>>> >>>> While this patch avoids the crashing, it apparently isn't >>>> correct...I'm getting IO errors reading files over the mount. :) >>>> >>> >>> I hit the same oops and tested your patch and it seems to have fixed >>> that particular panic, but I still see a bunch of other mem >>> corruption oopses even with it. I'll look more closely at that when >>> I get some time. >>> >>> FWIW, I can easily reproduce that by simply doing something like: >>> >>> $ dd if=/dev/urandom of=/file/on/nfsordma/mount bs=4k count=1 >>> >>> I'm not sure why you're not seeing any panics with your patch in >>> place. Perhaps it's due to hw differences between our test rigs. >>> >>> The EIO problem that you're seeing is likely the same client bug >>> that Chuck recently fixed in this patch: >>> >>> [PATCH 2/8] SUNRPC: Fix large reads on NFS/RDMA >>> >>> AIUI, Trond is merging that set for 3.15, so I'd make sure your >>> client has those patches when testing. >>> >> >> Nothing is in my queue yet. >> > > Doh! Any reason not to merge that set from Chuck? They do fix a couple > of nasty client bugs… > Most of them are one-line debugging dprintks which I do not intend to apply. One of them confuses a readdir optimisation with a bugfix; at the very least the patch comments need changing. That leaves 2 that can go in, however as they are clearly insufficient to make RDMA safe for general use, they certainly do not warrant a stable@ label. The workaround for the Oopses is simple: use TCP. _________________________________ Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@xxxxxxxxxxxxxxx -- 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
