From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793563373; b=4gkhVLadIlPvvBQY0QKqhjB/0+mh7ALrYSQ/0SFDmGabSZTqW/oS2zP/oCZu3hvDXHzt K5vpKi7tGy9RanTDZzZtYShNfLSocCyNmejz1QUhO7vwwlcmXSMBcxfT4rPs2eWeQoyNp ptFMVUqN/mSRcaXA25oUfyGmU+Rd0uau7xvCyUWpDhQcGqkZhTyuGOJCuAbR0Rt/0C2ov UUrpNpnJoYAJ0sBl6FILiS5op0+ewB6gg8GT4fo465y8C5CDkhv8ZsaJkE9F1p3SayATy NIC3Zq6wyFMLtLi3p+6W47NVIDEMpcKdhboH6c7ykRba6ysaTdXgWRzy8dcDkx+QsWQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793563373; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=0SOJOJhsdif+go/5LJX1b5wSejdt1NsbUiyp9y70uTo=; b=N5TcpWObLV+tpIiiz3Q/VvbZZDNAB0NhpBRsM0GB6kY0QEk8ElFbyrD8iSlEHWxPW24Q gTwAB+3aQerlWiYIzIKQBTyUpwVkJzukfcMo3jeiXjir4aBtbCJVpt5GoSsMVXKuFl3jZ pLJQrnz88r4ZGLT+rhDDXJj2cbNGCnk+pJNbs6H7Sklw4KhkUEI7Zq9gXPm0zL4ak7qIo ibPrKn1ecib7xN9Yb0Ag9cQk0E9A822QpTiQT8GLBlM8iHxTa09b1TGzIL6K/BVjrMVzX BDj8uQ7sHb5VI01cyRSouAbNQ7DwQk3elDvGRloo7Ovnh2m/FnAxM27P+cv97Zcb/ng== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WPNGg2UF; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 473B4606A335 for ; Sun, 1 Nov 2026 20:02:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WPNGg2UF Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BD5F1F00A1F; Sun, 1 Nov 2026 20:02:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793563372; bh=0SOJOJhsdif+go/5LJX1b5wSejdt1NsbUiyp9y70uTo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=WPNGg2UFCH8oHLxBKLsk+XSbOwxF9rgh4nqmQJ4tGq+b/EXkueNSv/mUnpHe3LXTa vVluDdes8rduQB1kHH0qnPxYIyTpIdeNMxc8d3/hE32sD/nAC42CBB2NZjzjwaoFKq VSfWDWS4ofbNNxRwkpWxOicfIWhXrFR5GTU++pvsJt1mFFhIjNQMHzbTibJdmUZwEl shnLe4dYc7bBcVf24pjhWeZ+yUtZLJ3rqG60ptgsmN8Uot0ZF7l/u6/9+ih0PTdWtU cK/6PBKoyC0PY6UDnhR/dmnnBtE45aSMdmbZobi90DRIuD7AmkyMtioQdRZsBRVIOO QgUz6fdgRIgag== Date: Sun, 1 Nov 2026 22:02:37 +0200 From: Mike Rapoport To: vrilutza@gmail.com Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Kees Cook , Borislav Petkov , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Ilya Leoshkevich Subject: Re: [PATCH v2 3/4] mm: Factor __pfn_valid() out of pfn_valid() Message-ID: References: <20261101-kmsan-serie-v2-0-f97f66dc57ef@gmail.com> <20261101-kmsan-serie-v2-3-f97f66dc57ef@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261101-kmsan-serie-v2-3-f97f66dc57ef@gmail.com> On Sun, Nov 01, 2026 at 07:04:38PM +0200, Viorel Cernateanu via B4 Relay wrote: > From: Viorel Cernateanu > > KMSAN needs to validate a PFN during metadata lookup without entering > instrumented code. Calling pfn_valid() also calls > rcu_read_lock_sched(), which can enter instrumented code and recurse > into the metadata lookup. > > Extract the PFN checks into __pfn_valid(), whose caller must already > be in an RCU-sched read-side critical section. Keep pfn_valid() as > the wrapper that acquires and releases that protection. > > This lets KMSAN reuse the existing PFN validation while providing > the required protection without instrumented helpers. > > The wrapper now also holds the RCU-sched read lock during the > initial range checks, which previously ran before acquiring it. > > Suggested-by: Alexander Potapenko > Signed-off-by: Viorel Cernateanu Acked-by: Mike Rapoport (Microsoft) > --- > include/linux/mmzone.h | 42 +++++++++++++++++++++++++----------------- > 1 file changed, 25 insertions(+), 17 deletions(-) -- Sincerely yours, Mike.