Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752312AbcLHKuQ (ORCPT ); Thu, 8 Dec 2016 05:50:16 -0500 Received: from mga01.intel.com ([192.55.52.88]:9203 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750982AbcLHKuP (ORCPT ); Thu, 8 Dec 2016 05:50:15 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,318,1477983600"; d="scan'208";a="200385308" Date: Thu, 8 Dec 2016 13:50:11 +0300 From: "Kirill A. Shutemov" To: =?iso-8859-1?B?Suly6W15?= Lefaure Cc: x86@kernel.org, Borislav Petkov , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/vm86: fix compilation warning on a unused variable Message-ID: <20161208105011.2jmuvlgdnirnv33b@black.fi.intel.com> References: <20161208043833.15088-1-jeremy.lefaure@lse.epita.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20161208043833.15088-1-jeremy.lefaure@lse.epita.fr> User-Agent: NeoMutt/20161126 (1.7.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 786 Lines: 19 On Wed, Dec 07, 2016 at 11:38:33PM -0500, Jérémy Lefaure wrote: > When CONFIG_TRANSPARENT_HUGEPAGE is disabled, split_huge_pmd is a no-op > stub. In such case, vma is unused and a compiler raises a warning: > > arch/x86/kernel/vm86_32.c: In function ‘mark_screen_rdonly’: > arch/x86/kernel/vm86_32.c:180:26: warning: unused variable ‘vma’ > [-Wunused-variable] > struct vm_area_struct *vma = find_vma(mm, 0xA0000); > ^~~ > Adding __maybe_unused in the vma declaration fixes this warning. Hm. pmd_trans_huge() is zero if CONFIG_TRANSPARENT_HUGEPAGE is not set. Compiler should get rid of whole block of code under the 'if'. Could you share your kernel config which triggers the warning? And what compiler do you use? -- Kirill A. Shutemov