Messages in this thread | | | From | Blaisorblade <> | Subject | Re: Remap_file_pages, RSS limits, security implications (was: Re: [uml-devel] Re: [RFC] [patch 0/18] remap_file_pages protection support (for UML), try 3) | Date | Wed, 21 Sep 2005 19:02:25 +0200 |
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On Wednesday 21 September 2005 18:50, Hugh Dickins wrote: > On Wed, 21 Sep 2005, Blaisorblade wrote: > > Other pages in the VMA may be unmapped, yes, but not freed. In fact, > > they're kept in by the pagecache reference; try_to_unmap() (or better its > > caller, shrink_list) will only actually free the page it asked for.
> Not freed in that pass, yes; but brought closer to being freed soon.
Will a page with mapcount == 0 be put in the inactive list explicitly? At next scan PageActive will be clear, sure, and it won't be reactivated while it's unmapped.
But references will only cause more hardware faults. > > The only real "problem" is that we do ptep_clear_flush_young without > > activating the page. And yes, *this* may penalize who holds a nonlinear > > VMA. But this is probably fair, given that we're going to have trouble in > > freeing those pages.
> Good point, I don't remember ever considering that. > But agree it should work out fairly.
> > > mm/trash.c? I got quite excited,
> > What would that have meant?
> Trash is rubbish or garbage. Or if I trash my hotel room (not me!), > I'd rip the washbasin off the wall, smash the mirror, throw the > chair through the window, ... hmm, better stop this public fantasy.
Nice... hope this can get to LWN "quotes of the week" page.
-- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade
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