Systemtap incompatible with ubuntu 18.04

[spbike]

Under 16.04 I ran run:
$ stap nfsd-trace.stp
Mon Oct 1 19:48:05 2018 PDT 10.22.7.20:50434 nfsd.proc4.lookup grep /export/1/blank/build.2018-08-22/bin/grep

Works great.

Under 18.04 I tried:
# stap nfsd-trace.stp
semantic error: while processing probe module("nfsd").function("nfsd4_lookup@/build/linux-lZKWha/linux-4.15.0/fs/nfsd/nfs4proc.c:735").call from: nfsd.proc4.lookup from: nfsd.proc.lookup from: nfsd.proc.entries from: nfsd.proc.entries

The kernel being used:
Linux nas-7-0 4.15.0-22-generic #24-Ubuntu SMP Wed May 16 12:15:17 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

I thought I might need a newer systemtap, so I installed it from git on Sept 27th 2018. So the same run:
/share/apps/systemtap-2018-09-27# ./bin/stap ./share/systemtap/examples/network/nfsd-trace.stp
semantic error: while processing probe module("nfsd").function("nfsd4_read@/build/linux-lZKWha/linux-4.15.0/fs/nfsd/nfs4proc.c:744").call from: nfsd.proc4.read from: nfsd.proc.read from: nfsd.proc.entries from: nfsd.proc.entries

Other scripts like iostats.stp work as expected.

So basically from what I can tell the neither the ubuntu provided systemtap, nor the upstream systemtap works with the widely circulated nfsd-trace.stp file. It's been available from redhat's documentation as well as part of the upstream source under examples.

I expected the 18.04 result of "stap nfsd-trace.stp" to be much like the 16.04 result. Showing a log of NFS related I/O, path names, time stamps, etc.

Other NFS related scripts like nfsd-recent.stp works.

[Frank Ch. Eigler (fche)]

Hi -

This commit appears to fix this problem.

https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=commitdiff;h=8bc64034509474bee3fb7996b2a9e74c8bc27281

[spbike (bill-broadley)]

On 10/19/18 2:38 PM, Frank Ch. Eigler wrote:
> Hi -
>
> This commit appears to fix this problem.
>
> https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=commitdiff;h=8bc64034509474bee3fb7996b2a9e74c8bc27281
>

It tried it, here's that file with the patch:
        version = 4
        fh = & @nfsd4_compound_state($cstate)->current_fh

        if (@defined($u)) {
             count = $u->read->rd_length
             offset = $u->read->rd_offset
             vec = $rqstp->rq_vec
             vlen = $u->read->rd_vlen
        } else {
             count = $read->rd_length
             offset = $read->rd_offset
             vec = $rqstp->rq_vec
             vlen = $read->rd_vlen
        }

        uid = __rqstp_uid($rqstp)
        gid = __rqstp_gid($rqstp)

I installed systemtap-4.0, ran ./configure --prefix=/share/apps/systemtap-4.0;
make; make install

Then ran it:
root@nas-12-1:/share/apps/systemtap-4.0# ./bin/stap
./share/systemtap/examples/network/nfsd-trace.stp
semantic error: while processing probe
module("nfsd").function("nfsd4_commit@/build/linux-39dmni/linux-4.15.0/fs/nfsd/nfs4proc.c:579").call
from: nfsd.proc4.commit from: nfsd.proc.commit from: nfsd.proc.entries from:
nfsd.proc.entries

semantic error: failed to retrieve location attribute for 'commit' [man
error::dwarf]: identifier '$commit' at
/share/apps/systemtap-4.0/share/systemtap/tapset/linux/nfsd.stp:856:10
        dieoffset: 0x1b5709 from
/usr/lib/debug/lib/modules/4.15.0-36-generic/kernel/fs/nfsd/nfsd.ko
        function: nfsd4_commit at
/build/linux-39dmni/linux-4.15.0/fs/nfsd/nfs4proc.c:581
        source: count = $commit->co_count
                         ^

semantic error: failed to retrieve location attribute for 'commit' [man
error::dwarf]: identifier '$commit' at :856:10
        dieoffset: 0x1b5709 from
/usr/lib/debug/lib/modules/4.15.0-36-generic/kernel/fs/nfsd/nfsd.ko
        function: nfsd4_commit at
/build/linux-39dmni/linux-4.15.0/fs/nfsd/nfs4proc.c:581
        source: count = $commit->co_count
                         ^

Pass 2: analysis failed. [man error::pass2]

I'll try building the current git version and see if that helps.

[spbike (bill-broadley)]

On 10/19/18 2:38 PM, Frank Ch. Eigler wrote:
> Hi -
>
> This commit appears to fix this problem.
>
> https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=commitdiff;h=8bc64034509474bee3fb7996b2a9e74c8bc27281
>

Apparently that commit depends on other commits. But if building from
git://sourceware.org/git/systemtap.git it does work with 18.04.

Many thanks for the find, I find systemtap indispensable.