On Sun, Mar 1, 2015 at 8:06 PM, Bruce James Fields <bfields@xxxxxxxxxxxx> wrote: > On Sun, Mar 01, 2015 at 07:52:28PM -0500, Trond Myklebust wrote: >> Hi Bruce, >> >> On Sun, Mar 1, 2015 at 2:14 PM, Trond Myklebust >> <trond.myklebust@xxxxxxxxxxxxxxx> wrote: >> > Hi, >> > >> > When doing testing of NFSv3 loopback mounts (client and server are on >> > the same IP address), I'm seeing a very reproducible hang in which the >> > client stops receiving data from the server. The TCP connection is still >> > marked as established, and the server appears to continue to receive and >> > send data, however the client does not. >> > >> > So far, I've reproduced on both v4.0-rc1, and the Fedora v3.18.7 kernel. >> > >> > The reproducer is simply to loopback mount using NFSv3, and then run the >> > 'fsx' filesystem exerciser. I'm usually able to trigger the hang with >> > "fsx -N 100000 foobar". >> > >> > I've attached a couple of wireshark trace of a few frames just before >> > and during the hang in case it jogs any memories. >> >> This bug appears to go away when I disable the splice()-based reads by >> clearing the RQ_SPLICE_OK flag. >> >> I noticed that it always involved a combination of a READ and a >> truncating SETATTR call. Are you sure that it is safe to share >> pagecache pages directly with sendpage() in this way? As far as I can >> tell, there is no locking to prevent them from being modified while in >> the TCP send queue. > > This is the stable-pages problem that we've had forever, isn't it? Or > is this a different problem? It is causing the TCP socket to hang, so it goes beyond the usual stable pages issue. -- 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
