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AJvYcCVzN8dGziCLu35+GZKC7sjDXatJk6qFEPOszUXulRvvLzEtodzzqqOAbHlfytyptfX4gJdzmLQH6A==@kvack.org X-Gm-Message-State: AOJu0Yzn6hjag1cUExda+Cu95p0dbTuOkCmijvB1Jb0RpzEAnf0P4cfE gsFfu+kGAjy1xDMWG4LADczwtUGPezlBDsCvLSSVDOwE4O3AT35Er+Gz00vwwpy4V9rUaBN+Z6i ++gL/Y+f/Q/kd2tOe4B6iWMOP0LA= X-Gm-Gg: ASbGncs5w5OEEYq3sjW8JvjbmXzYBfFmzN6tepoB8yngeM7HpyyW4x9A9T7Hol7/YAH jVDhuLg9HcO+WnrfRSp0ZaXnbE1g8wrCrEeiYbDUg1jtG6fpUKUDTx0gpjQYSm5pcnnAVLsTvQ3 /9eJl/3G4i/vHo5BL8ET6+hkE= X-Google-Smtp-Source: AGHT+IFr/ffU3S+Bcjd1sodOm+syXMczUvmTSuO46qAChScji4OUmr+q+4/zUEzHxk2aA8yhvLcXylE3LscFEHxeUTg= X-Received: by 2002:a5d:584a:0:b0:39c:30cd:352c with SMTP id ffacd0b85a97d-3a09fd6dddemr3186212f8f.8.1746394475826; Sun, 04 May 2025 14:34:35 -0700 (PDT) MIME-Version: 1.0 References: <20250428201409.5482-1-trintaeoitogc@gmail.com> In-Reply-To: <20250428201409.5482-1-trintaeoitogc@gmail.com> From: Andrey Konovalov Date: Sun, 4 May 2025 23:34:25 +0200 X-Gm-Features: ATxdqUEocI_y8g3-crzqqnu9TlwBMVPxrfYu5E8lZBzXKc40AXAeG5jrb780eco Message-ID: Subject: Re: [PATCH V3] mm: page-flags-layout.h: change the KASAN_TAG_WIDTH for HW_TAGS To: Guilherme Giacomo Simoes Cc: akpm@linux-foundation.org, pasha.tatashin@soleen.com, surenb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8C2FF180007 X-Stat-Signature: zxfpkzdr58t4nb9i5sdkh9rew6qwb8px X-Rspam-User: X-HE-Tag: 1746394477-339209 X-HE-Meta: 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 aldw7V/J MiqYuPWYbiEzGzbFdSS3UV6mltlPIIwvI27laNwaUo36xOufqPPYj9YljODbPDXcO2A/s22R8lp3M0ew5/YRpeCsW5nVPp0tzLgpb54j5dhHT/M2B1d0PH+Pw4/CPax87UlU0YN1QR8t1Q0CojFowcH606AKt+0C3gnwRtm20dKn2rdoQeQcwWW3BEoUpG5GYZ1P5LmCfsk1i6OEDiYTjpkdH13XHnI4F0gFPV/bK9zpj9kYHXJ3zbQXUjyyzoRbR/UYSDIeuUTCJf5nb4NNcrHuDcxhytMOVLNPfQryBEii8dNkywZxoX0OcMAZBtGe3B9Gyz6ylRQFwAWq5wU+liscA2MJmHlISKGMge4y12G4ddvIiTz0GzRic15xrolqZKKei5KER7UBFv+qt15kailm0XcaJheP6ICVpwUzqqtHtW04= 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 10:14=E2=80=AFPM 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. > > Suggested-by: Andrey Konovalov > Signed-off-by: Guilherme Giacomo Simoes > --- > V3 changes > - improve commit title > --- > 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 > Reviewed-by: Andrey Konovalov