From: Dave Hansen <dave.hansen@intel.com>
To: 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>,
Kees Cook <kees@kernel.org>,
"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 08:00:00 -0800 [thread overview]
Message-ID: <20fb97f1-7e50-485a-bdfd-a2901d20ec84@intel.com> (raw)
In-Reply-To: <20260119130122.1283821-1-ryan.roberts@arm.com>
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.
But I don't see any problems with the approach, and the move to common
code looks like a big win as well:
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
next prev parent reply other threads:[~2026-01-19 16:00 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 ` Dave Hansen [this message]
2026-01-19 16:44 ` [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation Kees Cook
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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