Re: ftruncate fails

["Eric Van Hensbergen" <eric.vanhensbergen@linux.dev>]

Itaru,

If you can, could confirm that your issues go away with the pending-fixes branch of the next tree?
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/?h=pending-fixes

I work for Arm as well, so if you could point me at the revision of FVP you are seeing the problems on I could also have a look at the server side of it and see if its breaking any assumptions we've been operating under using Qemu as our primary server.

     -eric


April 7, 2024 at 9:22 PM, "Itaru Kitayama" <itaru.kitayama@linux.dev> wrote:
> 
> > 
> > On Apr 8, 2024, at 11:08, Itaru Kitayama <itaru.kitayama@linux.dev> wrote:
> > 
> >  
> > 
> >  Hi,
> > 
> >  
> > 
> > > 
> > > On Apr 8, 2024, at 11:01, Dominique Martinet <asmadeus@codewreck.org> wrote:
> > > 
> > >  
> > > 
> > >  Itaru Kitayama wrote on Mon, Apr 08, 2024 at 10:44:51AM +0900:
> > > 
> > 
> >  With a recent kernel I see below program fails (Bus error) if executed
> > 
> >  from 9p mounted directory, not with the local filesystem (Ext4).
> > 
> > > 
> > > I cannot reproduce on 6.8/6.9-rc2 with qemu and a couple of options.
> > > 
> > >  Bus error would be some problem with the mmap of the executable given
> > > 
> > >  this code? so probably doesn't have anything to do with the content of
> > > 
> > >  the program itself...
> > > 
> > >  
> > > 
> > >  A few questions:
> > > 
> > >  - What exact kernel are you running? (or closest approximation)
> > > 
> > 
> >  
> > 
> >  v6.9-rc3
> > 
> >  
> > 
> > > 
> > > - What server? (assuming qemu) what mount option? (tried default
> > > 
> > >  cacheless and cache=loose)
> > > 
> > 
> >  
> > 
> >  FVP and just mount -t 9p FM /mnt
> > 
> >  
> > 
> > > 
> > > - Does this reproduce right after boot/mounting the 9p filesystem?
> > > 
> > 
> >  
> > 
> >  Not immediately after the boot/mounting.
> > 
> 
> My reproducer wasn’t explaining what a kselftests was showing.
> 
> If you build the “mm” subsystem and execute one of the programs, gup_longterm from the 9p mounted directory, you’ll notice the ftruncate error.
> 
> Thanks,
> 
> Itaru.
> 
> > 
> > Thanks,
> > 
> >  Itaru.
> > 
> >  
> > 
> > > 
> > > Thanks
> > > 
> > >  -- 
> > > 
> > >  Dominique Martinet | Asmadeus
> > >
> >
>