Re: process killed: text file modification

On Thursday, March 09, 2017 03:31:56 PM Gergely Czuczy wrote:
> [+freebsd-fs]
> 
> 
> On 2017. 03. 09. 14:20, Gergely Czuczy wrote:
> > On 2017. 03. 09. 11:27, Gergely Czuczy wrote:
> >> Hello,
> >>
> >> I'm trying to build a few things from ports on an rpi3, the ports 
> >> collection is mounted over NFS from another machine. When it's trying 
> >> to build pkg i'm getting the error message in syslog:
> >>
> >> rpi3 kernel: pid 4451 (sh), uid 0, was killed: text file modification
> >>
> >> The report to pkg_at_:
> >> https://lists.freebsd.org/pipermail/freebsd-pkg/2017-March/002048.html
> >>
> >> In ports-mgmt/pkg's config.log It fails at the following entry:
> >> configure:3726: checking whether we are cross compiling
> >> configure:3734: cc -o conftest -O2 -pipe  -Wno-error 
> >> -fno-strict-aliasing   conftest.c  >&5
> >> configure:3738: $? = 0
> >> configure:3745: ./conftest
> >> configure:3749: $? = 137
> >> configure:3756: error: in `/usr/ports/ports-mgmt/pkg/work/pkg-1.10.0':
> >> configure:3760: error: cannot run C compiled programs.
> >> If you meant to cross compile, use `--host'.
> >> See `config.log' for more details
> >>
> >> # uname -a
> >> FreeBSD rpi3 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r314949: Thu Mar 9 
> >> 08:58:46 CET 2017 
> >> aegir_at_marvin.harmless.hu:/tank/rpi3/crochet/work/obj/arm64.aarch64/tank/rpi3/src/sys/AEGIR 
> >> arm64
> > So far, a few additions:
> > Time is synced between the NFS server and the client.
> > it's an open() call which is getting the kill, and it's not the file 
> > what's being opened, but the process executing it.
> > Here's a simple code that reproduces it:
> > #include <stdio.h>
> >
> > int main() {
> >
> >   FILE *f = fopen ("/bar", "w");
> >
> >   fclose(f);
> >   return 0;
> > }
> >
> > Conditions to reproduce it:
> >  - The resulting binary must be executed from the nfs mount
> >  - The binary must be built after mounting the NFS share.
> >
> > I haven't tried building it on a different host, I don't have access 
> > to multiple RPis. Also, if I build the binary, umount/remount the NFS 
> > mount point, which has the binary, execute it, then it works.
> >
> > I've also tried this with the raspbsd.org's image, I could reproduce 
> > it as well.
> >
> > Another interesting thing is, when I first booted the RPi up, the NFS 
> > server was a 10.2-STABLE, and later got updated to 11-STABLE. While it 
> > was 10.2 I've tried to build some port, and I don't remember having 
> > this issue.
> >
> > So, could someone please help me figure this out and fix it? This 
> > stuff should work pretty much.
> >
> So, this error message comes from here:
> https://svnweb.freebsd.org/base/head/sys/fs/nfsclient/nfs_clbio.c?revision=314436&view=markup#l1674
> 
> It's the NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.na_mtime) 
> comparision that fails, np should be the NFS node structure, from the 
> vnode's v_data, and n_vattr is the attribute cache. As I've seen these 
> two are being updated together, so I don't really see by the code why 
> they might differ. Could someone please take a look at it, with more 
> experience in the NFS code? -czg

Can you print out the two mtimes?  I wonder if what's happening is that
your server uses different granularity (for example just seconds) than
your client, so on the client we generate a timestamp with a non-zero
nanoseconds but when the server receives that timestamp it "truncates"
it.  During open() we forcefully re-fetch the timestamp (for CTO
consistency) and then notice it doesn't match.  For now I would start
with comparing the timestamps and maybe the vfs.timestamp_precision
sysctls on client and server (if server is a FreeBSD box).

-- 
John Baldwin