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[209.85.217.45]) by smtp.gmail.com with ESMTPSA id n206sm23499791vkn.36.2019.02.05.15.11.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 Feb 2019 15:11:19 -0800 (PST) Received: by mail-vs1-f45.google.com with SMTP id z3so3293778vsf.7 for ; Tue, 05 Feb 2019 15:11:18 -0800 (PST) X-Received: by 2002:a67:e15e:: with SMTP id o30mr3333598vsl.66.1549408278541; Tue, 05 Feb 2019 15:11:18 -0800 (PST) MIME-Version: 1.0 References: <154899811208.3165233.17623209031065121886.stgit@dwillia2-desk3.amr.corp.intel.com> <154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.com> <20190205140415.544ae2876ee44e6edb8ca743@linux-foundation.org> In-Reply-To: <20190205140415.544ae2876ee44e6edb8ca743@linux-foundation.org> From: Kees Cook Date: Tue, 5 Feb 2019 23:11:06 +0000 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v10 1/3] mm: Shuffle initial free memory to improve memory-side-cache utilization To: Andrew Morton Cc: Dan Williams , Dave Hansen , Michal Hocko , Linux-MM , LKML , Keith Busch Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 5, 2019 at 10:04 PM Andrew Morton wrote: > > On Thu, 31 Jan 2019 21:15:17 -0800 Dan Williams wrote: > > > +config SHUFFLE_PAGE_ALLOCATOR > > + bool "Page allocator randomization" > > + default SLAB_FREELIST_RANDOM && ACPI_NUMA > > + help > > SLAB_FREELIST_RANDOM is default n, so this patchset won't get much > runtime testing. > > How about you cook up a (-mm only) patch which makes the kernel default > to SLAB_FREELIST_RANDOM=y, SHUFFLE_PAGE_ALLOCATOR=y (or whatever) to > ensure we get a decent amount of runtime testing? Then I can hold that > in -mm (and -next) until we get bored of it? I love this plan. :) FWIW, distros have enabled it by default for a while. Here's Ubuntu, for example: $ grep SLAB_FREELIST /boot/config-4.1* /boot/config-4.15.0-45-generic:CONFIG_SLAB_FREELIST_RANDOM=y /boot/config-4.15.0-45-generic:CONFIG_SLAB_FREELIST_HARDENED=y /boot/config-4.18.0-13-generic:CONFIG_SLAB_FREELIST_RANDOM=y /boot/config-4.18.0-13-generic:CONFIG_SLAB_FREELIST_HARDENED=y /boot/config-4.18.0-14-generic:CONFIG_SLAB_FREELIST_RANDOM=y /boot/config-4.18.0-14-generic:CONFIG_SLAB_FREELIST_HARDENED=y and Fedora too: $ curl -s 'https://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/fedora.git/patch/fedora/configs/kernel-4.16.12-x86_64.config?h=f26' | grep SLAB_FREELIST +CONFIG_SLAB_FREELIST_RANDOM=y +CONFIG_SLAB_FREELIST_HARDENED=y -- Kees Cook