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([177.21.143.178]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-309f77370b2sm6810067a91.8.2025.04.28.04.00.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Apr 2025 04:00:38 -0700 (PDT) From: Guilherme Giacomo Simoes To: akpm@linux-foundation.org, pasha.tatashin@soleen.com, surenb@google.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Guilherme Giacomo Simoes , Andrey Konovalov Subject: [PATCH V2] mm: alloc_tag: change the KASAN_TAG_WIDTH for HW_TAGS Date: Mon, 28 Apr 2025 08:00:30 -0300 Message-Id: <20250428110030.151265-1-trintaeoitogc@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" the KASAN_TAG_WIDTH is 8 bits for both (HW_TAGS and SW_TAGS), but for HW_TAGS the KASAN_TAG_WIDTH can be 4 bits bits because due to the design of the MTE the memory words for storing metadata only need 4 bits. Change the preprocessor define KASAN_TAG_WIDTH for check if SW_TAGS is define, so KASAN_TAG_WIDTH should be 8 bits, but if HW_TAGS is define, so KASAN_TAG_WIDTH should be 4 bits to save a few flags bits. Suggested-by: Andrey Konovalov Signed-off-by: Guilherme Giacomo Simoes --- V2 changes: - Improve commit message --- include/linux/page-flags-layout.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-l= ayout.h index 4f5c9e979bb9..760006b1c480 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -72,8 +72,10 @@ #define NODE_NOT_IN_PAGE_FLAGS 1 #endif =20 -#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) +#if defined(CONFIG_KASAN_SW_TAGS) #define KASAN_TAG_WIDTH 8 +#elif defined(CONFIG_KASAN_HW_TAGS) +#define KASAN_TAG_WIDTH 4 #else #define KASAN_TAG_WIDTH 0 #endif --=20 2.34.1