From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f69.google.com (mail-ot1-f69.google.com [209.85.210.69]) by kanga.kvack.org (Postfix) with ESMTP id 9AC298E0004 for ; Fri, 7 Dec 2018 16:10:17 -0500 (EST) Received: by mail-ot1-f69.google.com with SMTP id w24so2419958otk.22 for ; Fri, 07 Dec 2018 13:10:17 -0800 (PST) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id m5si1924792otk.80.2018.12.07.13.10.16 for ; Fri, 07 Dec 2018 13:10:16 -0800 (PST) Subject: Re: [PATCH v3 1/9] mm: Introduce new vm_insert_range API References: <20181206183945.GA20932@jordon-HP-15-Notebook-PC> <53bbc095-c9f5-5d6a-6e50-6e060d17eb68@arm.com> <20181207171116.GA29923@bombadil.infradead.org> From: Robin Murphy Message-ID: <67495f8f-2092-e42d-321e-5216c346513f@arm.com> Date: Fri, 7 Dec 2018 21:10:00 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Souptick Joarder , Matthew Wilcox Cc: Andrew Morton , Michal Hocko , "Kirill A. Shutemov" , vbabka@suse.cz, Rik van Riel , Stephen Rothwell , rppt@linux.vnet.ibm.com, Peter Zijlstra , Russell King - ARM Linux , iamjoonsoo.kim@lge.com, treding@nvidia.com, Kees Cook , Marek Szyprowski , stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, Heiko Stuebner , airlied@linux.ie, oleksandr_andrushchenko@epam.com, joro@8bytes.org, pawel@osciak.com, Kyungmin Park , mchehab@kernel.org, Boris Ostrovsky , Juergen Gross , linux-kernel@vger.kernel.org, Linux-MM , linux-arm-kernel@lists.infradead.org, linux1394-devel@lists.sourceforge.net, dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, xen-devel@lists.xen.org, iommu@lists.linux-foundation.org, linux-media@vger.kernel.org On 2018-12-07 7:28 pm, Souptick Joarder wrote: > On Fri, Dec 7, 2018 at 10:41 PM Matthew Wilcox wrote: >> >> On Fri, Dec 07, 2018 at 03:34:56PM +0000, Robin Murphy wrote: >>>> +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr, >>>> + struct page **pages, unsigned long page_count) >>>> +{ >>>> + unsigned long uaddr = addr; >>>> + int ret = 0, i; >>> >>> Some of the sites being replaced were effectively ensuring that vma and >>> pages were mutually compatible as an initial condition - would it be worth >>> adding something here for robustness, e.g.: >>> >>> + if (page_count != vma_pages(vma)) >>> + return -ENXIO; >> >> I think we want to allow this to be used to populate part of a VMA. >> So perhaps: >> >> if (page_count > vma_pages(vma)) >> return -ENXIO; > > Ok, This can be added. > > I think Patch [2/9] is the only leftover place where this > check could be removed. Right, 9/9 could also have relied on my stricter check here, but since it's really testing whether it actually managed to allocate vma_pages() worth of pages earlier, Matthew's more lenient version won't help for that one. (Why privcmd_buf_mmap() doesn't clean up and return an error as soon as that allocation loop fails, without taking the mutex under which it still does a bunch more pointless work to only undo it again, is a mind-boggling mystery, but that's not our problem here...) Robin.