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Thu, 20 Feb 2020 17:37:58 -0800 (PST) Received: from ubuntu-m2-xlarge-x86 ([2604:1380:4111:8b00::1]) by smtp.gmail.com with ESMTPSA id c10sm460048otl.77.2020.02.20.17.37.57 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 20 Feb 2020 17:37:57 -0800 (PST) Date: Thu, 20 Feb 2020 18:37:56 -0700 From: Nathan Chancellor To: Andrew Morton Cc: Catalin Marinas , linux-mm@kvack.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Nick Desaulniers Subject: Re: [PATCH v2] mm: kmemleak: Use address-of operator on section symbols Message-ID: <20200221013756.GA8323@ubuntu-m2-xlarge-x86> References: <20200220051551.44000-1-natechancellor@gmail.com> <20200220173501.0de88326911e41b15e27b62f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200220173501.0de88326911e41b15e27b62f@linux-foundation.org> User-Agent: Mutt/1.9.4 (2018-02-28) 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 Thu, Feb 20, 2020 at 05:35:01PM -0800, Andrew Morton wrote: > On Wed, 19 Feb 2020 22:15:51 -0700 Nathan Chancellor wrote: > > > Clang warns: > > > > These are not true arrays, they are linker defined symbols, which are > > just addresses. Using the address of operator silences the warning and > > does not change the resulting assembly with either clang/ld.lld or > > gcc/ld (tested with diff + objdump -Dr). > > I guess you forgot to quote the clang output? Ugh yes, sorry. I can send a v3 later or here it is if you want to stitch it in: ../mm/kmemleak.c:1955:28: warning: array comparison always evaluates to a constant [-Wtautological-compare] if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata) ^ ../mm/kmemleak.c:1955:60: warning: array comparison always evaluates to a constant [-Wtautological-compare] if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata) ^ 2 warnings generated. Cheers, Nathan