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Sat, 05 Sep 2026 12:29:57 -0700 (PDT) From: Matt Turner Date: Sat, 05 Sep 2026 15:29:36 -0400 Subject: [PATCH v2 15/22] alpha: select HAVE_GUP_FAST Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260905-arch-kconfig-options-v2-v2-15-83e8245761a2@gmail.com> References: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> In-Reply-To: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> To: Richard Henderson , Magnus Lindholm , Kees Cook , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, Matt Turner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1139; i=mattst88@gmail.com; h=from:subject:message-id; bh=qbVO92ABCC1+7CT9amMSlUYErry59m82RuIMiHqH71w=; b=owGbwMvMwCW25rVmCc8sv+mMp9WSGLLm5E6xNXGyqXZ0vv1g+ZG9qlMWzGNwm8jnsH3zFy171 yW3Nh5q6fjIwiDGxTBTTJElbr0iy6y2HUt9Tkv/gpnDygQyRFqkgQEIWBj4chPzSo10jPRMtQ31 DIEMHaN4iJweg0ZmcXFpapFuWkGRQ15+SWJJZn5esV5+QWpeQXqBXlpmWklGRn5RcSrQCL281BJ TV0c3I0MDE0tHCzMnC0dTE2dnJ0MnN0dHZ1cnI0tzEwNnS0cTV0tzBi5OAZhryv8zMjx7VPb1xJ IPi9qSYxY1Sj6ZUNP07+qkqULLcqafmfSlZY85I8OUddbSTbfc1IpXssw5wmlRN7No3n7hQKGwx LxIodK/IVwA X-Developer-Key: i=mattst88@gmail.com; a=openpgp; fpr=3BB639E56F861FA2E86505690FDD682D974CA72A The lockless GUP fast path needs the architecture to distinguish PTEs with no struct page behind them and to keep page table pages alive while a walker holds no lock. Alpha now has ARCH_HAS_PTE_SPECIAL, and it has selected MMU_GATHER_RCU_TABLE_FREE for a long time, so both requirements are met. PTEs are a single 64-bit word on Alpha, so the lockless reads that the generic walker performs cannot tear, and no arch-specific gup_fast_permitted() or ptep_get_lockless() is needed. Assisted-by: Claude:claude-opus-5 Signed-off-by: Matt Turner Tested-by: Magnus Lindholm Reviewed-by: Magnus Lindholm --- arch/alpha/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 4bd5e913baaf..1ba262812212 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -28,6 +28,7 @@ config ALPHA select HAVE_ARCH_COMPILER_H select HAVE_ASM_MODVERSIONS select HAVE_DEBUG_KMEMLEAK + select HAVE_GUP_FAST select HAVE_PAGE_SIZE_8KB select HAVE_PCSPKR_PLATFORM select HAVE_PERF_EVENTS -- 2.54.0