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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C44F4C433F5 for ; Thu, 20 Jan 2022 03:38:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=S4XBa/5UfQm87Mp+oc7lMVHdX0I8FDF5wYl+vVvjGE4=; b=4+JarF5/yLy8nK3iyXCeG2mydO IxATWWVGJG2reJKiQMALpP9OvZzoix2RreqwgmY6rXqlB7o/36LxyhLyOh+9Ra5Gw0hxaHuDEGGhd JtPCdCmVD9hehx48ovoJ+v5ZfOExTTJRVVyw1J7CyXUBzzwKHJU+k05KBmt0oeRh8Y93/ZUS/hMWd AGUrZHQikgVRf8Ds+HTDIKxCPtjGfR6kLXBTd5gQW7HCe83Q7XJeOrXCXFPi4nOvbjntxhoq6eXk3 nzRkUWpyR56EKIwJ/t5V61EKGcuzF2EywEKFEjISeTVqLbm728ks9lSuxzup3uIEt+7kIHSkUwZDc l9qWF8/Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nAOGF-008WQm-J4; Thu, 20 Jan 2022 03:37:19 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nAOGB-008WOm-Kz for linux-arm-kernel@lists.infradead.org; Thu, 20 Jan 2022 03:37:17 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8D8BC1FB; Wed, 19 Jan 2022 19:37:13 -0800 (PST) Received: from [10.163.74.136] (unknown [10.163.74.136]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 522953F766; Wed, 19 Jan 2022 19:37:07 -0800 (PST) Subject: Re: [PATCH] vmap(): don't allow invalid pages To: Yury Norov Cc: Matthew Wilcox , Catalin Marinas , Will Deacon , Andrew Morton , Nicholas Piggin , Ding Tianhong , Alexey Klimov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Uladzislau Rezki References: <20220118235244.540103-1-yury.norov@gmail.com> From: Anshuman Khandual Message-ID: <5b62ed03-8da8-a94d-cc48-a8cac1eae1c9@arm.com> Date: Thu, 20 Jan 2022 09:07:11 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220119_193715_779782_33B9A7B5 X-CRM114-Status: GOOD ( 10.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/19/22 10:52 PM, Yury Norov wrote: >> Why should not this just scan over the entire user provided struct page >> array and make sure that all pages there in are valid via above method, >> but in vmap() itself before calling vmap_pages_range(). Because seems >> like a single invalid page detected in vmap_pages_pte_range() will >> anyways abort the entire vmap(). This will also enable us to drop the >> existing NULL check above. > > I can do this, but why is it any better than the current approach? Because it will just return on the first instance where the valid page check fails, saving us some CPU cycles and an incomplete mapping ? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel