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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=WOhLQgtHBlaa6/9LcTJQIUBbipAiIKcaff5d+EZnw10=; b=HGZDEa+cAnFGpKg9lWPp4NT1IyYMVGR6JLcGIB59nEUrcjcdkjG7CNYNLV2eVW/Qcd XD0srgp6szwImsPitA5JPaLm41rkJvb6It3THmvGL/BYVWrLXwE140ZA1dxGMFTop6Sy fwU4vlu/NKmIHeu/Dtgq/9qWRDX9QdKw9shbs8jZQquSkoo7C4r+zsW5DeN044vUq35X GHj6MA9oPGO9HnOZAnlKTcA1PmEGUXx9KPOmHg9Uods1NTBQM6fp0KvD5/O+u/of8Hgd 2CzVI+X8prR1gt3p/z9zwDAZtJCD8hoT8eb1X7m6amQDGfXjvgqO63L4WoMBPwu6V3X+ AZtA== X-Gm-Message-State: AFqh2kphclYa0SkllF8t2D1L7yqsHCpG/VFiN1IJL+y6PKkp3YxZyqWL dUYyfOaDzDcFGH/zE0CKDZ6C1oNwN1UXDhb+uVg= X-Google-Smtp-Source: AMrXdXsS70rHo2N+FPLWUuDXEgJl0EoZKll493iXdf5EU3bDYdWcTSyssJJl2zqYAWiN9Ryhcx6DYMIRjcy7S3HsQFs= X-Received: by 2002:a17:90b:2541:b0:229:3af9:a0ac with SMTP id nw1-20020a17090b254100b002293af9a0acmr4227709pjb.47.1674593222835; Tue, 24 Jan 2023 12:47:02 -0800 (PST) MIME-Version: 1.0 References: <24ea20c1b19c2b4b56cf9f5b354915f8dbccfc77.1674592496.git.andreyknvl@google.com> <20230124124504.2b21f0fde58af208a4f4e290@linux-foundation.org> In-Reply-To: <20230124124504.2b21f0fde58af208a4f4e290@linux-foundation.org> From: Andrey Konovalov Date: Tue, 24 Jan 2023 21:46:51 +0100 Message-ID: Subject: Re: [PATCH mm] kasan: reset page tags properly with sampling To: Andrew Morton Cc: andrey.konovalov@linux.dev, Marco Elver , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov , Peter Collingbourne Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 0C83F140006 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 8wya64kzd9nsy8ra3i5c5f56g9km5a1h X-HE-Tag: 1674593223-528429 X-HE-Meta: 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 QRfeGIM6 D4Q36hALjCnstLINPnFcnm7XYlN+5X9f9qbWWezgnrnB48mH8sEEEtisb82PV42MQ7C3J3wYhw0/mSpWLK1AbQke22VbT5Vi07d9qbFcJXhpAEO6anBAIw3oUFYct6wcBMjZfz1JWbUQvpPlcmc81Jz4Skr9l3enVqPXUTe7Ge4o7ZAh+3eAvztCkXcEzihLsjjf/6MsaEwRTToVsFpgMVjp1Aido0fNKWL45OmUjqWPO8JkAinYWz9XwOBO+Exs60QqcBBfiSo/tMW6s403ydBmKd/Y9PDHCDEwRfgu3jz4BCl+emgaYlITiGRYR3Yb9u+2xVStZ1fOVbbB9SiMF5Xo/0rpQ9lQVP2vSK+ceyJRltG6nEK13VVQQnSHGqs6gp9wGyw4xKCp4KtU3iUc4Tdt5vw== 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: On Tue, Jan 24, 2023 at 9:45 PM Andrew Morton wrote: > > On Tue, 24 Jan 2023 21:35:26 +0100 andrey.konovalov@linux.dev wrote: > > > The implementation of page_alloc poisoning sampling assumed that > > tag_clear_highpage resets page tags for __GFP_ZEROTAGS allocations. > > However, this is no longer the case since commit 70c248aca9e7 > > ("mm: kasan: Skip unpoisoning of user pages"). > > > > This leads to kernel crashes when MTE-enabled userspace mappings are > > used with Hardware Tag-Based KASAN enabled. > > > > Reset page tags for __GFP_ZEROTAGS allocations in post_alloc_hook(). > > > > Also clarify and fix related comments. > > I assume this is a fix against 44383cef54c0 ("kasan: allow sampling > page_alloc allocations for HW_TAGS") which is presently in mm-stable, > yes? Correct. I assumed I shouldn't include a Fixes tag, as the patch is not in the mainline.