Re: [RFC][PATCH] Avoid vmtruncate/mmap-page-fault race

[Daniel Phillips]

On Thursday 29 May 2003 18:33, you wrote:
> On Thu, 29 May 2003, Paul E. McKenney wrote:
> > On Fri, May 23, 2003 at 11:42:02AM -0700, Paul E. McKenney wrote:
> > > Exactly -- allows a ->nopage() to drop some lock to avoid races
> > > between pagefault and either vmtruncate() or invalidate_mmap_range().
> > > This race (from the cross-host mmap viewpoint) is described in:
> > >
> > >     http://marc.theaimsgroup.com/?l=linux-kernel&m=105286345316249&w=2
> >
> > Rediffed for 2.5.70-mm1.
>
> Me?  I much preferred your original, much sparer, nopagedone patch
> (labelled "uglyh as hell" by hch).

"me too".

The fat patch that hits every fs to get rid of two lines and .5 cycles per 
no_page fault could be an epilogue (if/when it passes muster) to the little 
one that does the job and has already been thoroughly tested.

I see both sides of the argument.  The third side, not yet discussed, is the 
value of doing things incrementally, with widespread testing of the system at 
each step.

Regards,

Daniel