Re: Race in pagevec_strip?

[Hugh Dickins <hugh@veritas.com>]

On Thu, 16 Mar 2006, Christoph Lameter wrote:
> On Thu, 16 Mar 2006, Hugh Dickins wrote:
> > 
> > But I should add, I don't see what might be racing with what on the
> > same page, to cause the problem in practice.
> 
> The page is on the inactive list at the time pagevec_strip is called 
> (see refill_inactive_zone). So kswapd could get to it. Could filesystems 
> get to the page via the mapping?

A filesystem could get there, but I doubt it'd want to be releasing
buffers.  But now I see truncation's invalidate_complete_page,
that looks quite capable of racing with the kswapd instance.

Anyway, I don't disagree with your patch, and happy to see it now
in Linus' tree: was just wanting to make clear that I hadn't actually
seen the race in question, and didn't know if you were fixing a
potentiality or something actually seen.

Hugh