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Re: Read fault when running example network/nfsd-trace.stp stap
- From: Daniel Doron <danielmeirdoron at gmail dot com>
- To: Yun-Chih Chen <b03902074 at ntu dot edu dot tw>
- Cc: systemtap at sourceware dot org
- Date: Sat, 27 May 2017 22:34:54 +0300
- Subject: Re: Read fault when running example network/nfsd-trace.stp stap
- Authentication-results: sourceware.org; auth=none
- References: <CANeCTtTg0g9zP06XOVbKn-zoGujcsJiMNBebLC3vjDQ53NyYLg@mail.gmail.com>
ex_path is a struct path not a pointer to a struct path so maybe:
fh->fh_export->ex_path.mnt ?
On Fri, May 26, 2017 at 5:59 PM, Yun-Chih Chen <b03902074@ntu.edu.tw> wrote:
> I am running the example NFS stap file network/nfsd-trace.stp[1] on a
> NFS server.
> The stap file fails with the following message when a new NFS read
> request comes in:
>
> # sudo stap -v nfsd-trace.stp
> Pass 1: parsed user script and 467 library scripts using
> 138276virt/44988res/7568shr/37488data kb, in 130usr/20sys/154real ms.
> Pass 2: analyzed script: 22 probes, 66 functions, 9 embeds, 1 global
> using 342304virt/246608res/9036shr/241516data kb, in
> 6020usr/730sys/6779real ms.
> Pass 3: translated to C into
> "/tmp/stapoyPncz/stap_b12e64c3fc1fc31297eb3b8c93c2dacf_107403_src.c"
> using 342304virt/246856res/9228shr/241516data kb, in
> 200usr/70sys/265real ms.
> Pass 4: compiled C into
> "stap_b12e64c3fc1fc31297eb3b8c93c2dacf_107403.ko" in
> 4230usr/880sys/5113real ms.
> Pass 5: starting run.
> ERROR: read fault [man error::fault] at 0x0000000000000040 (addr) near
> operator '->' at nfsd-trace.stp:18:31
>
> It says "fh->fh_export->ex_path->mnt" is probably a reference on null
> pointer ....
>
> The test is conducted on both Linux 4.10 on Fedora 25 and Linux 3.10
> on CentOS 7. Both fails at the same place.
> Does anyone know what's going on here?
>
> Thanks,
>
>
> Yunchih
>
> [1] https://sourceware.org/systemtap/examples/network/nfsd-trace.stp