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X-CSE-ConnectionGUID: 2EJwRwjNSGSVIjzB6OUWEg== X-CSE-MsgGUID: 6WlZVx4FROSG1SEozpg1oA== X-IronPort-AV: E=McAfee;i="6800,10657,11520"; a="60903816" X-IronPort-AV: E=Sophos;i="6.17,284,1747724400"; d="scan'208";a="60903816" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2025 06:29:34 -0700 X-CSE-ConnectionGUID: t6kjFU4oRZiLZmMpMij85g== X-CSE-MsgGUID: TDLcIyj9Qy+UaemOVoZKVg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,284,1747724400"; d="scan'208";a="165831582" Received: from vpanait-mobl.ger.corp.intel.com (HELO wieczorr-mobl1.intel.com) ([10.245.245.54]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2025 06:29:12 -0700 From: Maciej Wieczor-Retman To: nathan@kernel.org, arnd@arndb.de, broonie@kernel.org, Liam.Howlett@oracle.com, urezki@gmail.com, will@kernel.org, kaleshsingh@google.com, rppt@kernel.org, leitao@debian.org, coxu@redhat.com, surenb@google.com, akpm@linux-foundation.org, luto@kernel.org, jpoimboe@kernel.org, changyuanl@google.com, hpa@zytor.com, dvyukov@google.com, kas@kernel.org, corbet@lwn.net, vincenzo.frascino@arm.com, smostafa@google.com, nick.desaulniers+lkml@gmail.com, morbo@google.com, andreyknvl@gmail.com, alexander.shishkin@linux.intel.com, thiago.bauermann@linaro.org, catalin.marinas@arm.com, ryabinin.a.a@gmail.com, jan.kiszka@siemens.com, jbohac@suse.cz, dan.j.williams@intel.com, joel.granados@kernel.org, baohua@kernel.org, kevin.brodsky@arm.com, nicolas.schier@linux.dev, pcc@google.com, andriy.shevchenko@linux.intel.com, wei.liu@kernel.org, bp@alien8.de, ada.coupriediaz@arm.com, xin@zytor.com, pankaj.gupta@amd.com, vbabka@suse.cz, glider@google.com, jgross@suse.com, kees@kernel.org, jhubbard@nvidia.com, joey.gouly@arm.com, ardb@kernel.org, thuth@redhat.com, pasha.tatashin@soleen.com, kristina.martsenko@arm.com, bigeasy@linutronix.de, maciej.wieczor-retman@intel.com, lorenzo.stoakes@oracle.com, jason.andryuk@amd.com, david@redhat.com, graf@amazon.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, mark.rutland@arm.com, dave.hansen@linux.intel.com, samuel.holland@sifive.com, kbingham@kernel.org, trintaeoitogc@gmail.com, scott@os.amperecomputing.com, justinstitt@google.com, kuan-ying.lee@canonical.com, maz@kernel.org, tglx@linutronix.de, samitolvanen@google.com, mhocko@suse.com, nunodasneves@linux.microsoft.com, brgerst@gmail.com, willy@infradead.org, ubizjak@gmail.com, peterz@infradead.org, mingo@redhat.com, sohil.mehta@intel.com Cc: linux-mm@kvack.org, linux-kbuild@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, llvm@lists.linux.dev, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 12/18] x86: Minimal SLAB alignment Date: Tue, 12 Aug 2025 15:23:48 +0200 Message-ID: X-Mailer: git-send-email 2.50.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 25B80140012 X-Stat-Signature: tkcuz4mqq6ddh13bchp1rz4cijd3yxdk X-HE-Tag: 1755005374-849732 X-HE-Meta: U2FsdGVkX18gRnVfZgklHyR4BnebULM8ZCIf6ywcE0n/y7UUKb8ciD62DEA0nmRRyvGbwzCpr18r2E5pNrte/wDPaaegN7XLeCM45wdYmc+NmJ/nvA7J81dI55Dwo4HQLRLwgcwvCrjDVVGhFG7oNPIAgVH7g1aqvWjyxwKgj4wFE2NeHOUM04TLjEMkZL+8LfYJTodcvWAXVsm7LR8btPWudFxNqCRvhkGOIeATKaRvVYMZG0ULbWwWSDDCGrlv3Q4zJ5HkQwYeMA58aEBuJTbLv44DBh4CKYTS3Gadr1AQYhZwmqbQKOyrLRNAxncKrf9tfe5Re53oRojR64NFUcwYP37jv+559WbVV21CVxAgfkgj5IR5U9GXxXQnRSNw1FqAblDJiMBjCE5kbORt5Ymyz4Q5dtsWOrInF0BXuLjrfafIJmloOjy6pCXitNiowE3Pqw71rQ8Vu65bSX4FpnS/ymh9AT62ZUkCDYAcoHzmjuP813m141CnYvHuTGtThrDVY2Uc2SJYekTbf0CZiHyvakbX16jv9aFu5Y62lNF0Iq3/3IZxj1ZzHGQH1Ymoglv3JRqQKcFZutj9SEGZ+5Eq5SvYUtQvLXeZ6pTX1m/ANfSrCLeGet7BvHCRbMdaBHV5DcSTi7dV47ctzskybhoRHLYjF7/G1x2y5obHEYdvInSzG0r3JG46K0OdggfuEQQGgSLVmei17Hosb2Mt7PMD6CmbQzQjcJ5nsIrjWolkNcY1Z+wOjEb2v1vnbP2DngWcum6d0xeuFnbV5Mi5o3TNu/RRTPZ+UkQH/Huz5QuYTDYAw7ZbjoYBNcmb+HlvIcrlfHNMIYaltXiwOuUInLtw+PbhzlleDaOURUk3787uZ6RpD2rK26ufgyQodLS3boq+ncLB28SeQYhAV4oWXDB1qzl00bBNN7y2g0u8spstGE8+ZgZ17k8n6IIbZIKUlHqT5BEK6ugGBqhASco ps+7Px+H giclPyQpZthEYkSWvrxcaA3oi46DjDDVIFNWByxPuqGIyxOQQj9LHjIh9UCWwy4W8yuyQaHDnXwPTLIur2TX4TbeAnvst7Yznuj2XKV4PteEuiJkmfE/azZ8Fwz+9DbbuRm0+nDepe3UHE2cr0MsGjpBp2RooE5GIeoyOy8s6JC3tMv75s7ExqSu2/FHmxH4Th9hPYB5aJlyY8RwgjoTksbHSAviNHpgvdCju3Ohim7ZMqPWfoWWDUBsX3sP3zZ8HA2S6 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 8 byte minimal SLAB alignment interferes with KASAN's granularity of 16 bytes. It causes a lot of out-of-bounds errors for unaligned 8 byte allocations. Compared to a kernel with KASAN disabled, the memory footprint increases because all kmalloc-8 allocations now are realized as kmalloc-16, which has twice the object size. But more meaningfully, when compared to a kernel with generic KASAN enabled, there is no difference. Because of redzones in generic KASAN, kmalloc-8' and kmalloc-16' object size is the same (48 bytes). So changing the minimal SLAB alignment of the tag-based mode doesn't have any negative impact when compared to the other software KASAN mode. Adjust x86 minimal SLAB alignment to match KASAN granularity size. Signed-off-by: Maciej Wieczor-Retman --- Changelog v4: - Extend the patch message with some more context and impact information. Changelog v3: - Fix typo in patch message 4 -> 16. - Change define location to arch/x86/include/asm/cache.c. arch/x86/include/asm/cache.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/include/asm/cache.h b/arch/x86/include/asm/cache.h index 69404eae9983..3232583b5487 100644 --- a/arch/x86/include/asm/cache.h +++ b/arch/x86/include/asm/cache.h @@ -21,4 +21,8 @@ #endif #endif +#ifdef CONFIG_KASAN_SW_TAGS +#define ARCH_SLAB_MINALIGN (1ULL << KASAN_SHADOW_SCALE_SHIFT) +#endif + #endif /* _ASM_X86_CACHE_H */ -- 2.50.1