Date: Tue, 15 Feb 2005 13:14:53 +0000 (GMT)
From: Hugh Dickins <hugh@veritas.com>
To: Andrea Arcangeli <andrea@suse.de>
cc: Andi Kleen <ak@suse.de>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, Dave Hansen <haveblue@us.ibm.com>
Subject: Re: fix iounmap and a pageattr memleak (x86 and x86-64)
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On Tue, 15 Feb 2005, Andrea Arcangeli wrote:
> On Tue, Feb 15, 2005 at 11:51:52AM +0100, Andi Kleen wrote:
> 
> It's not just for cosmetic reasons that I suggest to change this. My
> point is that the _real_ reason why we had the bug in the first place is
> that people forgets that p->size includes the guard page (because it
> shouldn't include the guard page). The fundamental problem of vmalloc
> exposing the guard page to the callers (which makes it prone for
> mistakes, and prone for breakage if somebody needs all virtual space and
> removes the guard page), isn't solved yet.

Strongly agree with you.  I remember this nuisance from large-page-patch
days: the guard page (if any) really should be an implementation detail
private to mm/vmalloc.c, never exposed outside.

> > No problem with changing it, but hopefully after 2.6.11.
> 
> Ok fine with me, take your time it's clearly not urgent because in
> practice no bug can be triggered anymore ;). thanks!

Yes, not urgent.  The instance of exposure I remember is one of the
PAGE_SIZEs in fs/proc/kcore.c.

Hugh
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