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Date: Thu, 18 Apr 2019 15:07:36 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Alexander Potapenko <glider@...gle.com>, akpm@...ux-foundation.org,
cl@...ux.com, dvyukov@...gle.com, keescook@...omium.org, labbott@...hat.com
Cc: linux-mm@...ck.org, linux-security-module@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 0/3] RFC: add init_allocations=1 boot option
On 4/18/19 8:42 AM, Alexander Potapenko wrote:
> Following the recent discussions here's another take at initializing
> pages and heap objects with zeroes. This is needed to prevent possible
> information leaks and make the control-flow bugs that depend on
> uninitialized values more deterministic.
>
> The patchset introduces a new boot option, init_allocations, which
> makes page allocator and SL[AOU]B initialize newly allocated memory.
> init_allocations=0 doesn't (hopefully) add any overhead to the
> allocation fast path (no noticeable slowdown on hackbench).
>
> With only the the first of the proposed patches the slowdown numbers are:
> - 1.1% (stdev 0.2%) sys time slowdown building Linux kernel
> - 3.1% (stdev 0.3%) sys time slowdown on af_inet_loopback benchmark
> - 9.4% (stdev 0.5%) sys time slowdown on hackbench
>
> The second patch introduces a GFP flag that allows to disable
> initialization for certain allocations. The third page is an example of
third patch
> applying it to af_unix.c, which helps hackbench greatly.
>
> Slowdown numbers for the whole patchset are:
> - 1.8% (stdev 0.8%) on kernel build
> - 6.5% (stdev 0.2%) on af_inet_loopback
> - 0.12% (stdev 0.6%) on hackbench
>
>
> Alexander Potapenko (3):
> mm: security: introduce the init_allocations=1 boot option
> gfp: mm: introduce __GFP_NOINIT
> net: apply __GFP_NOINIT to AF_UNIX sk_buff allocations
>
> drivers/infiniband/core/uverbs_ioctl.c | 2 +-
> include/linux/gfp.h | 6 ++++-
> include/linux/mm.h | 8 +++++++
> include/linux/slab_def.h | 1 +
> include/linux/slub_def.h | 1 +
> include/net/sock.h | 5 +++++
> kernel/kexec_core.c | 4 ++--
> mm/dmapool.c | 2 +-
> mm/page_alloc.c | 18 ++++++++++++++-
> mm/slab.c | 14 ++++++------
> mm/slab.h | 1 +
> mm/slab_common.c | 15 +++++++++++++
> mm/slob.c | 3 ++-
> mm/slub.c | 9 ++++----
> net/core/sock.c | 31 +++++++++++++++++++++-----
> net/unix/af_unix.c | 13 ++++++-----
> 16 files changed, 104 insertions(+), 29 deletions(-)
>
--
~Randy
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