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Subject: Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, "H. Peter Anvin" <hpa@zytor.com>
References: <20161227015413.187403-1-kirill.shutemov@linux.intel.com>
 <20161227015413.187403-30-kirill.shutemov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>, Andy Lutomirski <luto@amacapital.net>,
        linux-arch@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <5a3dcc25-b264-37c7-c090-09981b23940d@intel.com>
Date: Thu, 5 Jan 2017 11:13:57 -0800
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On 12/26/2016 05:54 PM, Kirill A. Shutemov wrote:
> MM would use min(RLIMIT_VADDR, TASK_SIZE) as upper limit of virtual
> address available to map by userspace.

What happens to existing mappings above the limit when this upper limit
is dropped?

Similarly, why do we do with an application running with something
incompatible with the larger address space that tries to raise the
limit?  Say, legacy MPX.