Re: [LSF/MM] schedule suggestion

[Matthew Wilcox <willy@infradead.org>]

On Thu, Apr 19, 2018 at 03:31:08PM -0400, Jerome Glisse wrote:
> > > Basicly i want a callback in __fd_install(), do_dup2(), dup_fd() and
> > > add void * *private_data; to struct fdtable (also a default array to
> > > struct files_struct). The callback would be part of struct file_operations.
> > > and only call if it exist (os overhead is only for device driver that
> > > care).
> > > 
> > > Did i miss something fundamental ? copy_files() call dup_fd() so i
> > > should be all set here.
> > > 
> > > I will work on patches i was hoping this would not be too much work.
> 
> Well scratch that whole idea, i would need to add a new array to task
> struct which make it a lot less appealing. Hence a better solution is
> to instead have this as part of mm (well indirectly).

It shouldn't be too bad to add a struct radix_tree to the fdtable.

I'm sure we could just not support weird cases like sharing the fdtable
without sharing the mm.  Does anyone actually do that?