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Date:   Wed, 3 Oct 2018 06:56:11 +0200
From:   Eugene Syromiatnikov <esyr@redhat.com>
To:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc:     x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Arnd Bergmann <arnd@arndb.de>,
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        Balbir Singh <bsingharora@gmail.com>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
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        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
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        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [RFC PATCH v4 24/27] mm/mmap: Create a guard area between VMAs
Message-ID: <20181003045611.GB22724@asgard.redhat.com>
References: <20180921150351.20898-1-yu-cheng.yu@intel.com>
 <20180921150351.20898-25-yu-cheng.yu@intel.com>
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On Fri, Sep 21, 2018 at 08:03:48AM -0700, Yu-cheng Yu wrote:
> Create a guard area between VMAs, to detect memory corruption.

Do I understand correctly that with this patch a user space program
no longer be able to place two mappings back to back? If it is so,
it will likely break a lot of things; for example, it's a common ring
buffer implementations technique, to map buffer memory twice back
to back in order to avoid special handling of items wrapping its end.