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AJvYcCVTfTaiK2Vq5Uv4XHyKUkIXxYPscUNOC5fpSqdUpdpavD44d5AGQTFXyMQwGh7+8FbLgx2RtS0qhw==@kvack.org X-Gm-Message-State: AOJu0YwWB8kGLPwuL4T5onB48bvEfyq3533hRP6bSik6g7KXbUjMUwq1 D9adfM1vAI2G9mdQVtA8L0FXZ579IS5azLhK16SR4GJJXcEmr5aRN7TsqF6eIht3JEwKVszOLFj A28DCwErnCHsHaRILrFJpqpsBu+rak8y1AA8H X-Gm-Gg: ASbGnct/wYt9ydlnk/xN5jGDzgqqbyhmU0eUfUAyMMV8lOHaZ/4ODfuBLqIleOVVPqm NVg+vbd4tdXy9t4SSTBrb2LWi9+iE/pqz6PE/bvngPSbtviZ0L+U42z/1TXuoysxOVQiw99Srdb wHGQJJnrWI7vXHJwsjnZ07V6A8DAey8eI= X-Google-Smtp-Source: AGHT+IGC8BcBrZ+OsNHPMrSSJp0ngSL9gh6C30RowYt7MLOBGERB0KUxUozIcK96e8Y2xwDGbe0NI8EsTveVxeRefaA= X-Received: by 2002:ac8:7c52:0:b0:480:18d4:93ff with SMTP id d75a77b69052e-487fb9ef28dmr452101cf.12.1745856116221; Mon, 28 Apr 2025 09:01:56 -0700 (PDT) MIME-Version: 1.0 References: <20250428110030.151265-1-trintaeoitogc@gmail.com> In-Reply-To: <20250428110030.151265-1-trintaeoitogc@gmail.com> From: Suren Baghdasaryan Date: Mon, 28 Apr 2025 09:01:44 -0700 X-Gm-Features: ATxdqUHrPKwca8-_S84UfHAAD1rxlHz0n8hql1KjZQSNuKge-jfQNOoEIazZNB0 Message-ID: Subject: Re: [PATCH V2] mm: alloc_tag: change the KASAN_TAG_WIDTH for HW_TAGS To: Guilherme Giacomo Simoes Cc: akpm@linux-foundation.org, pasha.tatashin@soleen.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 73EDD40004 X-Stat-Signature: xhixugocb5egshxm6xnua159qi4gqwq3 X-Rspam-User: X-HE-Tag: 1745856117-171158 X-HE-Meta: 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 dXQ16S7Q hfcXrXUWD8uA5VpZoN5657uwMXeH9r1HYw6he37aBjKMFYPpXmJTzPu6UrczwfhP6FJQN6ZlTjsji0zopgYePJ2wxAYzKMfZAet3akPsWBQpIF1VyuU0VvEqssECzz7xTn9AMhPlTApiGP01FlcILzyJy0/JDoTou/0fwlmI/0klnnnqaWpOu4/gqIqadA/igNjNHtwty4sRfeKooexV+3nzvbOHFPkShD24Y4Sw6eO8GjT82OvdRE2unIceCKImBSTQC2+PzdQgFAE+qwopQdo5YY89ooIu53BwBc2MrfZT0HiU= 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: On Mon, Apr 28, 2025 at 4:00=E2=80=AFAM Guilherme Giacomo Simoes wrote: > > 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. The title lists "alloc_tag" but the change does not directly relate to allocation tags. I think it should be page-flags-layout.h instead. > > 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= -layout.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 > > -#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 > -- > 2.34.1 >