From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bombadil.infradead.org ([198.137.202.133]:56664 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388263AbeKPEWp (ORCPT ); Thu, 15 Nov 2018 23:22:45 -0500 Subject: Re: [PATCH 1/9] mm: Introduce new vm_insert_range API To: Souptick Joarder , akpm@linux-foundation.org, willy@infradead.org, mhocko@suse.com, kirill.shutemov@linux.intel.com, vbabka@suse.cz, riel@surriel.com, sfr@canb.auug.org.au, rppt@linux.vnet.ibm.com, peterz@infradead.org, linux@armlinux.org.uk, robin.murphy@arm.com, iamjoonsoo.kim@lge.com, treding@nvidia.com, keescook@chromium.org, m.szyprowski@samsung.com, stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, heiko@sntech.de, airlied@linux.ie, oleksandr_andrushchenko@epam.com, joro@8bytes.org, pawel@osciak.com, kyungmin.park@samsung.com, mchehab@kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, 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 References: <20181115154530.GA27872@jordon-HP-15-Notebook-PC> From: Randy Dunlap Message-ID: <9655a12e-bd3d-aca2-6155-38924028eb5d@infradead.org> Date: Thu, 15 Nov 2018 10:13:36 -0800 MIME-Version: 1.0 In-Reply-To: <20181115154530.GA27872@jordon-HP-15-Notebook-PC> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 11/15/18 7:45 AM, Souptick Joarder wrote: > Previouly drivers have their own way of mapping range of > kernel pages/memory into user vma and this was done by > invoking vm_insert_page() within a loop. > > As this pattern is common across different drivers, it can > be generalized by creating a new function and use it across > the drivers. > > vm_insert_range is the new API which will be used to map a > range of kernel memory/pages to user vma. > > Signed-off-by: Souptick Joarder > Reviewed-by: Matthew Wilcox > --- > include/linux/mm_types.h | 3 +++ > mm/memory.c | 28 ++++++++++++++++++++++++++++ > mm/nommu.c | 7 +++++++ > 3 files changed, 38 insertions(+) Hi, What is the opposite of vm_insert_range() or even of vm_insert_page()? or is there no need for that? > diff --git a/mm/memory.c b/mm/memory.c > index 15c417e..da904ed 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1478,6 +1478,34 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr, > } > > /** > + * vm_insert_range - insert range of kernel pages into user vma > + * @vma: user vma to map to > + * @addr: target user address of this page > + * @pages: pointer to array of source kernel pages > + * @page_count: no. of pages need to insert into user vma s/no./number/ > + * > + * This allows drivers to insert range of kernel pages they've allocated > + * into a user vma. This is a generic function which drivers can use > + * rather than using their own way of mapping range of kernel pages into > + * user vma. > + */ > +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; > + > + for (i = 0; i < page_count; i++) { > + ret = vm_insert_page(vma, uaddr, pages[i]); > + if (ret < 0) > + return ret; For a non-trivial value of page_count: Is it a problem if vm_insert_page() succeeds for several pages and then fails? > + uaddr += PAGE_SIZE; > + } > + > + return ret; > +} > + > +/** > * vm_insert_page - insert single page into user vma > * @vma: user vma to map to > * @addr: target user address of this page thanks. -- ~Randy