linux-kernel - Re: Removing MAX_ARG_PAGES (request for comments/assistance)

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Message-ID: <65dd6fd50610111448q7ff210e1nb5f14917c311c8d4@mail.gmail.com>
Date:	Wed, 11 Oct 2006 14:48:14 -0700
From:	"Ollie Wild" <aaw@...gle.com>
To:	"Peter Zijlstra" <a.p.zijlstra@...llo.nl>
Cc:	linux-kernel@...r.kernel.org, parisc-linux@...ts.parisc-linux.org,
	"Linus Torvalds" <torvalds@...l.org>,
	"Arjan van de Ven" <arjan@...radead.org>,
	"Ingo Molnar" <mingo@...e.hu>, linux-mm@...ck.org,
	"Andrew Morton" <akpm@...l.org>, "Andi Kleen" <ak@....de>,
	linux-arch@...r.kernel.org, "David Howells" <dhowells@...hat.com>
Subject: Re: Removing MAX_ARG_PAGES (request for comments/assistance)

> Yeah, you'll need to change the PTEs for those pages you created by
> calling get_user_page() by calling an mprotect like function; perhaps
> something like:

Thanks.  I've incorporated your changes (updated patch attached).

> > +               /* Move stack pages down in memory. */
> > +               if (stack_shift) {
> > +                       // FIXME: Verify the shift is OK.
> > +
>
> What exactly are you wondering about? the call to move_vma looks sane to
> me

My concern was that the binfmt handler may have setup other vm areas
which overlap the new range.  The move_vma() function doesn't do
overlap checking.  I'm not sure if this is something I need to guard
against, or if it falls in the "Don't do that!" category.

Ollie

Download attachment "no_MAX_ARG_PAGES.patch" of type "application/octet-stream" (27310 bytes)