Date: Tue, 28 Jul 2015 19:39:20 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Ahmed Kamal <email.ahmedkamal@googlemail.com> Cc: Graham Allan <allan@physics.umn.edu>, Ahmed Kamal via freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: Linux NFSv4 clients are getting (bad sequence-id error!) Message-ID: <1089316279.4709692.1438126760802.JavaMail.zimbra@uoguelph.ca> In-Reply-To: <CANzjMX5Q4TNLBxrAm6R2F6oUdfgRD8dX1LRZiniJA4M4HTN_=w@mail.gmail.com> References: <684628776.2772174.1435793776748.JavaMail.zimbra@uoguelph.ca> <184170291.10949389.1437161519387.JavaMail.zimbra@uoguelph.ca> <CANzjMX4NmxBErtEu=e5yEGJ6gAJBF4_ar_aPdNDO2-tUcePqTQ@mail.gmail.com> <55B12EB7.6030607@physics.umn.edu> <1935759160.2320694.1437688383362.JavaMail.zimbra@uoguelph.ca> <CANzjMX48F1gAVwqq64q=yALfTBNEc7iMbKAK1zi6aUfoF3WpOw@mail.gmail.com> <576106597.2326662.1437688749018.JavaMail.zimbra@uoguelph.ca> <CANzjMX5Q4TNLBxrAm6R2F6oUdfgRD8dX1LRZiniJA4M4HTN_=w@mail.gmail.com>
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[-- Attachment #1 --] Ahmed Kamal wrote: > Hi again Rick, > > Seems that I'm still being unlucky with nfs :/ I caught one of the newly > installed RHEL6 boxes having high CPU usage, and bombarding the BSD NFS box > with 10Mbps traffic .. I caught a tcpdump as you mentioned .. You can > download it here: > > https://dl.dropboxusercontent.com/u/51939288/nfs41-high-client-cpu.pcap.bz2 > Ok, the packet trace suggests that the NFSv4 server is broken (it is replying with NFS4ERR_STALE_CLIENTID for a recently generated ClientID). Now, I can't be sure, but the only explanation I can come up with is... - For some arches (I only have i386, so I wouldn't have seen this during testing), time_t is 64bits (uint64_t). --> If time_seconds somehow doesn't fit in the low order 32bits, then the code would be busted for these arches because nfsrvboottime is set to time_seconds when the server is started and then there are comparisons like: if (nfsrvboottime != clientid.lval[0]) return (NFSERR_STALECLIENTID); /* where clientid.lval[0] is a uint32_t */ Anyhow, if this is what is happening, the attached simple patch should fix it. (I don't know how time_seconds would exceed 4billion, but the clock code is pretty convoluted, so I can't say if it can possibly happen?) rick ps: Hmm, on i386 time_seconds ends up at 1438126486, so maybe it can exceed 4*1024*1024*1024 - 1 on amd64? > I didn't restart the client yet .. so if you catch me in the next few hours > and want me to run any diagnostics, let me know. Thanks a lot all for > helping > > On Thu, Jul 23, 2015 at 11:59 PM, Rick Macklem <rmacklem@uoguelph.ca> wrote: > > > Ahmed Kamal wrote: > > > Can you please let me know the ultimate packet trace command I'd need to > > > run in case of any nfs4 troubles .. I guess this should be comprehensive > > > even at the expense of a larger output size (which we can trim later).. > > > Thanks a lot for the help! > > > > > tcpdump -s 0 -w <file>.pcap host <client-host-name> > > (<file> refers to a file name you choose and <client-host-name> refers to > > the host name of a client generating traffic.) > > --> But you won't be able to allow this to run for long during the storm > > or the > > file will be huge. > > > > Then you look at <file>.pcap in wireshark, which knows NFS. > > > > rick > > > > > On Thu, Jul 23, 2015 at 11:53 PM, Rick Macklem <rmacklem@uoguelph.ca> > > wrote: > > > > > > > Graham Allan wrote: > > > > > For our part, the user whose code triggered the pathological > > behaviour > > > > > on SL5 reran it on SL6 without incident - I still see lots of > > > > > sequence-id errors in the logs, but nothing bad happened. > > > > > > > > > > I'd still like to ask them to rerun again on SL5 to see if the > > "accept > > > > > skipped seqid" patch had any effect, though I think we expect not. > > Maybe > > > > > it would be nice if I could get set up to capture rolling tcpdumps of > > > > > the nfs traffic before they run that though... > > > > > > > > > > Graham > > > > > > > > > > On 7/20/2015 10:26 PM, Ahmed Kamal wrote: > > > > > > Hi folks, > > > > > > > > > > > > I've upgraded a test client to rhel6 today, and I'll keep an eye > > on it > > > > > > to see what happens. > > > > > > > > > > > > During the process, I made the (I guess mistake) of zfs send | > > recv to > > > > a > > > > > > locally attached usb disk for backup purposes .. long story short, > > > > > > sharenfs property on the received filesystem was causing some > > > > nfs/mountd > > > > > > errors in logs .. I wasn't too happy with what I got .. I > > destroyed the > > > > > > backup datasets and the whole pool eventually .. and then rebooted > > the > > > > > > whole nas box .. After reboot my logs are still flooded with > > > > > > > > > > > > Jul 21 05:12:36 nas kernel: nfsrv_cache_session: no session > > > > > > Jul 21 05:13:07 nas last message repeated 7536 times > > > > > > Jul 21 05:15:08 nas last message repeated 29664 times > > > > > > > > > > > > Not sure what that means .. or how it can be stopped .. Anyway, > > will > > > > > > keep you posted on progress. > > > > > > > > > Oh, I didn't see the part about "reboot" before. Unfortunately, it > > sounds > > > > like the > > > > client isn't recovering after the session is lost. When the server > > > > reboots, the > > > > client(s) will get NFS4ERR_BAD_SESSION errors back because the server > > > > reboot has > > > > deleted all sessions. The NFS4ERR_BAD_SESSION should trigger state > > > > recovery on the client. > > > > (It doesn't sound like the clients went into recovery, starting with a > > > > Create_session > > > > operation, but without a packet trace, I can't be sure?) > > > > > > > > rick > > > > > > > > > > > > > > -- > > > > > > > ------------------------------------------------------------------------- > > > > > Graham Allan - gta@umn.edu - allan@physics.umn.edu > > > > > School of Physics and Astronomy - University of Minnesota > > > > > > > ------------------------------------------------------------------------- > > > > > > > > > > > > > > > > > > > > [-- Attachment #2 --] --- fs/nfsserver/nfs_nfsdstate.c.sav 2015-07-28 18:54:06.561454000 -0400 +++ fs/nfsserver/nfs_nfsdstate.c 2015-07-28 19:00:20.351089000 -0400 @@ -487,7 +487,7 @@ nfsrv_getclient(nfsquad_t clientid, int if (clpp) *clpp = NULL; if ((nd == NULL || (nd->nd_flag & ND_NFSV41) == 0 || - opflags != CLOPS_RENEW) && nfsrvboottime != clientid.lval[0]) { + opflags != CLOPS_RENEW) && (uint32_t)nfsrvboottime != clientid.lval[0]) { error = NFSERR_STALECLIENTID; goto out; } @@ -683,7 +683,7 @@ nfsrv_destroyclient(nfsquad_t clientid, struct nfsclienthashhead *hp; int error = 0, i, igotlock; - if (nfsrvboottime != clientid.lval[0]) { + if ((uint32_t)nfsrvboottime != clientid.lval[0]) { error = NFSERR_STALECLIENTID; goto out; } @@ -3996,11 +3996,11 @@ nfsrv_checkrestart(nfsquad_t clientid, u */ if (flags & (NFSLCK_OPEN | NFSLCK_TEST | NFSLCK_RELEASE | NFSLCK_DELEGPURGE)) { - if (clientid.lval[0] != nfsrvboottime) { + if (clientid.lval[0] != (uint32_t)nfsrvboottime) { ret = NFSERR_STALECLIENTID; goto out; } - } else if (stateidp->other[0] != nfsrvboottime && + } else if (stateidp->other[0] != (uint32_t)nfsrvboottime && specialid == 0) { ret = NFSERR_STALESTATEID; goto out;
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