From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B248631E852 for ; Tue, 3 Mar 2026 09:12:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772529138; cv=none; b=SbslmsxSTueO8XOdtEPDbRmmZMM4zEdX5nw5rJHwUTzaei2y2MYh9kV/6fL9TBFmseDLxyS4KC++N93KLp7gLIt9D1jdzXir3INx2WW99SYJufDwipkq7hnkMDYg7TQeOkXcPa/WpmXqa+jd3DDaOnG8Ivpv9HRja0ARGBjxufA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772529138; c=relaxed/simple; bh=ECc7z7tsidz26oiQwOHWeZRLOlNbNjwxKg4L1JltJrw=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Y7dL3ZOI4KmL15mQVAqR5kG0P/a7I8sdBrmFuXjgVNbcEgh1FoRalfXKXmOp0KzKd3wVUPeXk6Iz558XoIvdgryK3tHd+PCr0M9KnCv1J+FE4UVrN2+8qeA68N9oZsKdiHBvKV2jfWJrwCWGYVFXMzq1WPtGLY9btOFr3xVkzAg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=D6gbYfiq; arc=none smtp.client-ip=209.85.128.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="D6gbYfiq" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-483770e0b25so46037115e9.0 for ; Tue, 03 Mar 2026 01:12:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1772529135; x=1773133935; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=4hy9xICo1EPoOGuMUjTJL88qGfqc1hJzlCloLKGWnZI=; b=D6gbYfiqZ9Rub9Nna+8CpTbHrvLLEBybstalgCCNYJt05H5XiJLBCCrkaJmEVbnx93 0DeEZNj+JuPY305863XQwrg2W5OaLpXpiKDVn7ZgSmmvWJfk5840zZpwrBQoxGsVLr2V 941nJYizTDY3i1Xx5kR8DX5eJuPf4xhvBWtjtqF28lloXnh68KfNtDSQSNkBBUKoUg/y 75+9TOCLECMjRUoh9+A+fQk3sUCtJbO+hb0c3+hLPph8RtG3OlD/lEc8gK/my+ranH9o rvHNfk2gUF1JF9rJtRS/8mjTju073gBH6L927ZI6BGkoDsfJfUfkFC99zJXs7W7YsGdL 7UKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772529135; x=1773133935; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=4hy9xICo1EPoOGuMUjTJL88qGfqc1hJzlCloLKGWnZI=; b=f4bVQZrzpoX7xAghYtTxJvcVXyls15ll+UZukVylnihC46UfBHNANs8kGZFLcGzMFq GLmEB0v6Y4UwIeG+Z5vzcVQ1aL+20lkmgKe+/XzO7Sc0+58H/V8+1zdk8t5yN2qc8/U8 +aP476ChSSnL/1qN3V0uHS2/DmCSCJZLMIwJ3uG+r85W2bGO+LKYgPRF3fAIKFiUfgYD 6RGk4yYb7YvdloS+xvD7QOuL2q1+Iqi6F79Jc//JmKDcakXrKrDh3TMkXiFdD7LXIE0d tRvcBnb1FyS1WpZds0X/fk+VIEBnMkaQxBmQR8IUmEpkZc734SVPVBuDL96IgQNZTHWg 5bvQ== X-Forwarded-Encrypted: i=1; AJvYcCW+hFrN5OhWyg0v5S1ZkdaONh6dGdBMmvo+u4JAVbW1MPZ8zzjOmj7Ng1KDv8m7rVKYsyWmRNg7A08bMCA=@vger.kernel.org X-Gm-Message-State: AOJu0YwZ8/rhwvhNLNp758tgE32nBikxwqgMfcHXSevJNBwF7J+Nvm5p yGulod/E++zOhftFQ4ZLr7Yr50IevyO+rpb/KAGtMVoT5Y32ZbxAGl7S X-Gm-Gg: ATEYQzx2rOHLagqsRhsMTeToTUABjex92XpK0fj5UGqMANZDnzNlHOCOvSEkuSwUEeh t4gVaCCPQ10HYWuqws2pJ/Uyhh9GvnonMUzn7CPPs6t/2Li5x38FV4s3HmEX1sMMALn2oiCvzFR pKn+0hfN92gDTJAa1SwDBYwcDQBdmXkC532yxKSqY4BtSxzZjyzKOQ2BS86QeR/7wmDiNT4FOQE iGw0vR19IoYMvvOZRre0fPRSLTWMCoohMOH5Th894mStWTOud0mXUIMea7tqfT63AfCFNF9GFsu 8IZhjxIqRd0ezIbXQYRFvfCRtvVTXQ18UMpiBp+hwIM45u48AiR6IXLqs36a4GyDQeWl/C9uRdV P7QDKrPDcu0shrpesSWhxKDe2yVRVCjQXK2g/REz2CLNIJBI6UTQkXfgkoafhbMZeMIU9V5uDKB 62yyn1LmJEiu5IfzsIsl43pQ3VXEUVl5PB2maxuYsFXLdiPVEixcAQlHWiAmI3hPbd X-Received: by 2002:a05:600c:3542:b0:480:1e8f:d15f with SMTP id 5b1f17b1804b1-483c9bc5596mr280473755e9.2.1772529134880; Tue, 03 Mar 2026 01:12:14 -0800 (PST) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48512692c14sm13045615e9.7.2026.03.03.01.12.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Mar 2026 01:12:14 -0800 (PST) Date: Tue, 3 Mar 2026 09:12:12 +0000 From: David Laight To: "Christophe Leroy (CS GROUP)" Cc: Alexander Viro , Andre Almeida , Andrew Cooper , Christian Borntraeger , Christian Brauner , Darren Hart , Davidlohr Bueso , Heiko Carstens , Jan Kara , Julia Lawall , Linus Torvalds , linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, LKML , Madhavan Srinivasan , Mathieu Desnoyers , Michael Ellerman , Nicholas Piggin , Nicolas Palix , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Russell King , Sven Schnelle , Thomas Gleixner , x86@kernel.org, Kees Cook , akpm@linux-foundation.org Subject: Re: [PATCH v2 4/5] uaccess: Disable -Wshadow in __scoped_user_access() Message-ID: <20260303091212.620241c8@pumpkin> In-Reply-To: References: <20260302132755.1475451-1-david.laight.linux@gmail.com> <20260302132755.1475451-5-david.laight.linux@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Mon, 2 Mar 2026 16:00:26 +0100 "Christophe Leroy (CS GROUP)" wrote: > Le 02/03/2026 =C3=A0 14:27, david.laight.linux@gmail.com a =C3=A9crit=C2= =A0: > > From: David Laight > >=20 > > -Wshadow is enabled by W=3D2 builds and __scoped_user_access() quite > > deliberately creates a 'const' shadow of the 'user' address that > > references a 'guard page' when the application passes a kernel pointer. > >=20 > > Signed-off-by: David Laight =20 >=20 > There is a problem with this patch: (badly line-wrapped errors deleted) It seems to need gcc 12. (So Linus is in luck.) Prior to gcc 12 the #pragma generated by _Pragma() act as the controlled statement of the for () loop. Trying to put the _Pragma() inside the for statement doesn't work at all. David