NFS client/buffer cache deadlock

Marc Olzheim marcolz at
Tue Apr 26 09:06:11 PDT 2005

On Tue, Apr 26, 2005 at 11:50:43AM -0400, Brian Fundakowski Feldman wrote:
> > I'm okay with the fact that simultaneous huge writes to the same file
> > over NFS could lead to corruption and that the exact outcome is
> > undefined.
> > 
> > This is exactly how it was in FreeBSD 4.x and that's perfectly workable.
> > 
> > But that's just my way of looking at it and certainly not ideal. :-/
> I don't know what you mean.  The exact same bug should exists in 4.x,
> and should cause a system deadlock in exactly the same scenario.

I'm not sure you understand the "scenario". All I do is create a new
file and writev 600 * 1MB to it. This creates a VFS hangup on FreeBSD
5.x after writing an amount of 2-100 MB (depending on how much memory is
in the system), while 4.x just does what it is told and doesn't hangup.

I do not have any synchronisation problems.

See kern/79208

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