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Date: Thu, 14 Dec 2017 18:36:53 +0100
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2 02/17] mm: Exempt special mappings from mlock(),
 mprotect() and madvise()
Message-ID: <20171214173653.s6vsgiwfty3tzyzs@hirez.programming.kicks-ass.net>
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To: Andy Lutomirski <luto@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Dave Hansen <dave.hansen@intel.com>, Borislav Petkov <bpetkov@suse.de>, Greg KH <gregkh@linuxfoundation.org>, Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>, Brian Gerst <brgerst@gmail.com>, Josh Poimboeuf <jpoimboe@redhat.com>, Denys Vlasenko <dvlasenk@redhat.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Juergen Gross <jgross@suse.com>, David Laight <David.Laight@aculab.com>, Eduardo Valentin <eduval@amazon.com>, "Liguori, Anthony" <aliguori@amazon.com>, Will Deacon <will.deacon@arm.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Dan Williams <dan.j.williams@intel.com>

On Thu, Dec 14, 2017 at 08:19:36AM -0800, Andy Lutomirski wrote:
> On Thu, Dec 14, 2017 at 3:27 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > It makes no sense to ever prod at special mappings with any of these
> > syscalls.
> >
> > XXX should we include munmap() ?
> 
> This is an ABI break for the vdso.  Maybe that's okay, but mremap() on
> the vdso is certainly used, and I can imagine debuggers using
> mprotect().

*groan*, ok so mremap() will actually still work after this, but yes,
mprotect() will not. I hadn't figured people would muck with the VDSO
like that.

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