Re: [bug report] NFS and uninterruptable wait states

["Peter Wächtler" <pwaechtler@loewe-komp.de>]

David Woodhouse wrote:
> 
> doug@wireboard.com said:
> >  NFS does this (wait in D state) by default in order to prevent naive
> > applications from getting timeout errors that they're not equipped to
> > handle--the idea being that, if an NFS server goes down, programs
> > using it will simply freeze and recover once it returns, rather than
> > getting a timeout error and possibly becoming confused.
> 
> Timeouts are a completely separate issue, surely? Applications ought to be
> able to deal with getting a _signal_ during a system call, whatever happens.
> 
> IMO, sleeping in state TASK_UNINTERRUPTIBLE in any situation where you can't
> prove that the wakeup _will_ happen and will happen _soon_ should be
> considered a bug - it's almost always just because someone hasn't bothered
> to implement the cleanup code required for dealing with being interrupted.
> 
> /me tries to work out why anyone would ever want filesystem accesses to be
> uninterruptible.
> 
Because historically the 'D' meant "wait on _D_isk" 8-)