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From:   Florian Weimer <fweimer@redhat.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        Dave Martin <Dave.Martin@arm.com>
Subject: Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function
References: <20190606200926.4029-1-yu-cheng.yu@intel.com>
        <20190606200926.4029-4-yu-cheng.yu@intel.com>
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        <aa8a92ef231d512b5c9855ef416db050b5ab59a6.camel@intel.com>
        <20190607174336.GM3436@hirez.programming.kicks-ass.net>
        <b3de4110-5366-fdc7-a960-71dea543a42f@intel.com>
        <34E0D316-552A-401C-ABAA-5584B5BC98C5@amacapital.net>
        <7e0b97bf1fbe6ff20653a8e4e147c6285cc5552d.camel@intel.com>
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        <e26f7d09376740a5f7e8360fac4805488b2c0a4f.camel@intel.com>
        <3f19582d-78b1-5849-ffd0-53e8ca747c0d@intel.com>
        <5aa98999b1343f34828414b74261201886ec4591.camel@intel.com>
        <0665416d-9999-b394-df17-f2a5e1408130@intel.com>
        <5c8727dde9653402eea97bfdd030c479d1e8dd99.camel@intel.com>
        <ac9a20a6-170a-694e-beeb-605a17195034@intel.com>
        <328275c9b43c06809c9937c83d25126a6e3efcbd.camel@intel.com>
        <92e56b28-0cd4-e3f4-867b-639d9b98b86c@intel.com>
Date:   Tue, 11 Jun 2019 09:24:03 +0200
In-Reply-To: <92e56b28-0cd4-e3f4-867b-639d9b98b86c@intel.com> (Dave Hansen's
        message of "Mon, 10 Jun 2019 15:02:45 -0700")
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* Dave Hansen:

> My assumption has always been that these large, potentially sparse
> hardware tables *must* be mmap()'d with MAP_NORESERVE specified.  That
> should keep them from being problematic with respect to overcommit.

MAP_NORESERVE pages still count towards the commit limit.  The flag only
disables checks at allocation time, for this particular allocation.  (At
least this was the behavior the last time I looked into this, I
believe.)

Not sure if this makes a difference here.

Thanks,
Florian