From: Kees Cook <kees@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Mark Rutland <mark.rutland@arm.com>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Ard Biesheuvel <ardb@kernel.org>,
Jeremy Linton <jeremy.linton@arm.com>,
David Laight <david.laight.linux@gmail.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation
Date: Mon, 19 Jan 2026 08:44:17 -0800 [thread overview]
Message-ID: <C502BCE6-2FB2-4A06-93A8-E8DEDFC22914@kernel.org> (raw)
In-Reply-To: <20fb97f1-7e50-485a-bdfd-a2901d20ec84@intel.com>
On January 19, 2026 8:00:00 AM PST, Dave Hansen <dave.hansen@intel.com> wrote:
>On 1/19/26 05:01, Ryan Roberts wrote:
>> x86 (AWS Sapphire Rapids):
>> +-----------------+--------------+-------------+---------------+
>> | Benchmark | Result Class | v6.18-rc5 | per-task-prng |
>> | | | rndstack-on | |
>> | | | | |
>> +=================+==============+=============+===============+
>> | syscall/getpid | mean (ns) | (R) 13.32% | (R) 4.60% |
>> | | p99 (ns) | (R) 13.38% | (R) 18.08% |
>> | | p99.9 (ns) | 16.26% | (R) 19.38% |
>
>Like you noted, this is surprising. This would be a good thing to make
>sure it goes in very early after -rc1 and gets plenty of wide testing.
Right, we are pretty late in the dev cycle (rc6). It would be prudent to get this into -next after the coming rc1 (1 month from now).
On the other hand, the changes are pretty "binary" in the sense that mistakes should be VERY visible right away. Would it be better to take this into -next immediately instead?
>But I don't see any problems with the approach, and the move to common
>code looks like a big win as well:
Agreed; I think it's looking great.
--
Kees Cook
next prev parent reply other threads:[~2026-01-19 16:44 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-19 13:01 [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation Ryan Roberts
2026-01-19 13:01 ` [PATCH v4 1/3] randomize_kstack: Maintain kstack_offset per task Ryan Roberts
2026-01-19 16:10 ` Dave Hansen
2026-01-19 16:51 ` Ryan Roberts
2026-01-19 16:53 ` Dave Hansen
2026-01-19 13:01 ` [PATCH v4 2/3] prandom: Add __always_inline version of prandom_u32_state() Ryan Roberts
2026-01-28 17:00 ` Jason A. Donenfeld
2026-01-28 17:33 ` Ryan Roberts
2026-01-28 18:32 ` David Laight
2026-01-30 16:16 ` Christophe Leroy (CS GROUP)
2026-01-19 13:01 ` [PATCH v4 3/3] randomize_kstack: Unify random source across arches Ryan Roberts
2026-01-20 23:50 ` kernel test robot
2026-01-21 10:20 ` David Laight
2026-01-21 14:48 ` David Laight
2026-01-21 10:52 ` Ryan Roberts
2026-01-21 12:32 ` Mark Rutland
2026-02-18 15:20 ` Ryan Roberts
2026-02-22 21:34 ` Thomas Gleixner
2026-02-23 9:41 ` David Laight
2026-03-03 14:43 ` Ryan Roberts
2026-01-19 16:00 ` [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation Dave Hansen
2026-01-19 16:44 ` Kees Cook [this message]
2026-01-19 16:51 ` Dave Hansen
2026-01-20 16:32 ` Ryan Roberts
2026-01-20 16:37 ` Dave Hansen
2026-01-20 16:45 ` Ryan Roberts
2026-01-20 18:45 ` David Laight
2026-01-19 16:25 ` Heiko Carstens
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