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[140.211.169.12]) by mx.google.com with ESMTPS id 5si31501124plc.425.2019.04.15.13.57.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Apr 2019 13:57:10 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) client-ip=140.211.169.12; Authentication-Results: mx.google.com; spf=pass (google.com: domain of akpm@linux-foundation.org designates 140.211.169.12 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from X1 (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 19A17CB2; Mon, 15 Apr 2019 20:57:10 +0000 (UTC) Date: Mon, 15 Apr 2019 13:57:08 -0700 From: Andrew Morton To: Manfred Spraul Cc: kbuild test robot , kbuild-all@01.org, Linux Memory Management List , Waiman Long , Davidlohr Bueso Subject: Re: [linux-next:master 6345/7161] ipc/util.c:226:13: note: in expansion of macro 'max' Message-Id: <20190415135708.0dbc9e3ddb5afeb47bd52ce4@linux-foundation.org> In-Reply-To: References: <201904130252.Ws2iLv7w%lkp@intel.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 Sun, 14 Apr 2019 20:21:30 +0200 Manfred Spraul wrote: >=20 > With sysctl disabled, ipc_min_cycle is RADIX_TREE_MAP_SIZE, and this is >=20 > > include/linux/radix-tree.h:#define RADIX_TREE_MAP_SIZE=A0 (1UL <<=20 > RADIX_TREE_MAP_SHIFT) >=20 > The checker behind max() is not smart enough to notice that=20 > RADIX_TREE_MAP_SIZE can be represented as int without an overflow. >=20 >=20 > What is the right approach? >=20 Make ipc_min_cycle have the same type in both cases? --- a/ipc/util.h~ipc-do-cyclic-id-allocation-for-the-ipc-object-fix +++ a/ipc/util.h @@ -42,7 +42,7 @@ extern int ipc_min_cycle; #else /* CONFIG_SYSVIPC_SYSCTL */ =20 #define ipc_mni IPCMNI -#define ipc_min_cycle RADIX_TREE_MAP_SIZE +#define ipc_min_cycle ((int)RADIX_TREE_MAP_SIZE) #define ipcmni_seq_shift() IPCMNI_SHIFT #define IPCMNI_IDX_MASK ((1 << IPCMNI_SHIFT) - 1) #endif /* CONFIG_SYSVIPC_SYSCTL */ _