From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 50701EA8116 for ; Tue, 10 Feb 2026 13:41:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B852E6B0005; Tue, 10 Feb 2026 08:41:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B332B6B0088; Tue, 10 Feb 2026 08:41:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A5C1D6B0089; Tue, 10 Feb 2026 08:41:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 974A66B0005 for ; Tue, 10 Feb 2026 08:41:11 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 3BDA4160491 for ; Tue, 10 Feb 2026 13:41:11 +0000 (UTC) X-FDA: 84428658342.16.BEB7BE1 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id 7163B4000C for ; Tue, 10 Feb 2026 13:41:09 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nIllKt5t; spf=pass (imf01.hostedemail.com: domain of pratyush@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1770730869; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Unc9qKAicQ/3X4+uqvXt+dYinmIoJsSf6GoPz9zE95w=; b=XLv5WirACqLXJhsFLHdkGeppTRV19B+D8DDD53N7Tjgy25JigmjC5lgqJqnDPlsUurLy6M P5+1yecmKj++sm011dMuw92n5aCREsULP7PBXyBuI75ovBS3TxacFwJ2+yXV/ONzdCgHnP AeV0Nw5uHwN6UqqXMhTTSFH7XCOt2JE= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nIllKt5t; spf=pass (imf01.hostedemail.com: domain of pratyush@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=pratyush@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770730869; a=rsa-sha256; cv=none; b=z3ogLfmEaGe9qgQn5rRpsNosjdpGfLU9tRAOBiXVcO/NG8zBV0ZRJuP/fkfpFvVp4X4sK0 9x+tgRCHnHtYkulUBTjF6ZV2TGh7p0tPIl5ojXK6GStVouotVtsyA2A+Mb1pvBn2xdrdLX yGTsqmp96/ZF1BYT4P7/qYYsjcS7wig= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 4E73541A8D; Tue, 10 Feb 2026 13:41:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9288C116C6; Tue, 10 Feb 2026 13:41:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770730868; bh=MT+rctIKmuvnA5eIBAxzoWBQTwTyMz/PD/htQtTMRHA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=nIllKt5tMFMZhddu4EvDabsmw0eHTKy8WZOr+dKIUK3L85tK4gxTBXSx759Vo8FSP UEUEtJQRapO+RGb5Lej1n6r3xYUdyvdxWW6Xey2r3uABmMd57mYgPNF/1Vlizl4A/y 2Lan/KlFtdWKApPbiTGiOpjdxcEhW5ODyj7+1LjCroZc7eJcd4z7PKmoVr9lV2hUUR hLDipo1c38yuDNcZaraPl5Four8CUKGTqKpey2Dkjbh8XtIagfqAnKbKvqvYZnrhIb XX/7t3NPvotDvDyaeHdjj7EwR++IqchPlbh/kdhhIuc3QtygKOiXDz2mIWRIrKu/SA o00paYupoA1MA== From: Pratyush Yadav To: David Binderman Cc: "graf@amazon.com" , "rppt@kernel.org" , "pasha.tatashin@soleen.com" , "pratyush@kernel.org" , "kexec@lists.infradead.org" , "linux-mm@kvack.org" , LKML Subject: Re: linux-6.19-rc8/kernel/liveupdate/kexec_handover.c:1089: Possible 32/64 bit mixup ? In-Reply-To: (David Binderman's message of "Thu, 5 Feb 2026 09:21:17 +0000") References: Date: Tue, 10 Feb 2026 14:41:05 +0100 Message-ID: <2vxzzf5gsolq.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: 4dfpuhfmdkufty446che8wfkc44sfxqb X-Rspamd-Queue-Id: 7163B4000C X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1770730869-884802 X-HE-Meta: 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 4IZIUJbY NFcfoQAb9KoIjWC7NwOCpU3jL4CR8OsyZVD0s+M6LlD7289uqtHuzjGdKzeGRzCpa3M2k5iMnM98U5q8H00p2zzwdIRPeOJCW8R1LHQfBiufHvqlqmtPqWu4fK1YnR2RG99yaZ4f3PPCkCt53XeG/n3qnThmAwYdyA8um5b8ZkMoYIkecc6loMZjQWIDTUP28fV8M65VXVnwlTRmk9jcKNzpXT4R40SfifOiWu3Os92WGWtMqurWlKIqqHdi53a4wCvCNf3iq0Wl+xNsP+DsgWIHgxI9QP2xXsr8WTWGrQaa5oWk= 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: List-Subscribe: List-Unsubscribe: Hi David, On Thu, Feb 05 2026, David Binderman wrote: > Hello there, > > Source code analyser cppcheck says: > > linux-6.19-rc8/kernel/liveupdate/kexec_handover.c:1089:15: style: int result is > assigned to long variable. If the variable is long to avoid loss of information, > then you have loss of information. [truncLongCastAssignment] > > Source code is > > contig_pages = (1 << order); > > I admit the error message is hard to understand, but AFAIK > if local variable order remains under 30 or so, then there is no problem. > > However, if it goes above 32, then there will be loss of data. > Expression 1 << order is type int. > > Suggest add some code or comment to document the expected range > of local variable order. If it ever goes above 32, suggest new code > > contig_pages = 1UL << order; If order is 32, with 4k pages, that means 16 TiB. It is unlikely that we will see vmalloc area backed by pages this large any time soon. So I am not worried about any practical problems. But I think this is still a good idea to do for code hygiene. So a patch would be much appreciated. -- Regards, Pratyush Yadav