Re: anon_vma RFC2

Hugh Dickins
2004-03-12T13:55:48Z

On Fri, 12 Mar 2004, Andrea Arcangeli wrote:
> On Fri, Mar 12, 2004 at 04:46:38AM -0800, William Lee Irwin III wrote:
> >
> > The case where mremap() creates rmap_chains is so rare I never ever saw
> > it happen in 6 months of regular practical use and testing. Their
> > creation could be triggered only by remap_file_pages().
>
> did you try specweb with apache? that's super heavy mremap as far as I
> know (and it maybe using anon memory, and if not I certainly cannot
> exclude other apps are using mremap on significant amounts of anymous
> ram).

anonmm has no problem with most mremaps: the special case is for
mremap MAYMOVE of anon vmas _inherited from parent_ (same page at
different addresses in the different mms). As I said before, it's
quite conceivable that this case never arises outside our testing
(but I'd be glad to be shown wrong, would make effort worthwhile).

Hugh