linux-kernel - Re: [PATCH 1/9] mm: Introduce new vm_insert

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Message-Id: <20181119162623.GA13200@rapoport-lnx>
Date:   Mon, 19 Nov 2018 08:26:24 -0800
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Souptick Joarder <jrdr.linux@...il.com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        vbabka@...e.cz, Rik van Riel <riel@...riel.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        rppt@...ux.vnet.ibm.com, Peter Zijlstra <peterz@...radead.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        robin.murphy@....com, iamjoonsoo.kim@....com, treding@...dia.com,
        Kees Cook <keescook@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        stefanr@...6.in-berlin.de, hjc@...k-chips.com,
        Heiko Stuebner <heiko@...ech.de>, airlied@...ux.ie,
        oleksandr_andrushchenko@...m.com, joro@...tes.org,
        pawel@...iak.com, Kyungmin Park <kyungmin.park@...sung.com>,
        mchehab@...nel.org, Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        Linux-MM <linux-mm@...ck.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux1394-devel@...ts.sourceforge.net,
        dri-devel@...ts.freedesktop.org,
        linux-rockchip@...ts.infradead.org, xen-devel@...ts.xen.org,
        iommu@...ts.linux-foundation.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 1/9] mm: Introduce new vm_insert_range API

On Mon, Nov 19, 2018 at 08:43:09PM +0530, Souptick Joarder wrote:
> Hi Mike,
> 
> On Sat, Nov 17, 2018 at 8:07 PM Matthew Wilcox <willy@...radead.org> wrote:
> >
> > On Sat, Nov 17, 2018 at 12:26:38PM +0530, Souptick Joarder wrote:
> > > On Fri, Nov 16, 2018 at 11:59 PM Mike Rapoport <rppt@...ux.ibm.com> wrote:
> > > > > + * 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
> > > > > + *
> > > > > + * 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.
> > > >
> > > > Please add the return value and context descriptions.
> > > >
> > >
> > > Sure I will wait for some time to get additional review comments and
> > > add all of those requested changes in v2.
> >
> > You could send your proposed wording now which might remove the need
> > for a v3 if we end up arguing about the wording.
> 
> Does this description looks good ?
> 
> /**
>  * 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: number of pages need to insert into user vma
>  *
>  * 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.
>  *
>  * Context - Process context. Called by mmap handlers.

Context:

>  * Return - int error value

Return:

>  * 0                    - OK
>  * -EINVAL              - Invalid argument
>  * -ENOMEM              - No memory
>  * -EFAULT              - Bad address
>  * -EBUSY               - Device or resource busy

I don't think that elaborate description of error values is needed, just "0
on success and error code otherwise" would be sufficient.

>  */
> 

-- 
Sincerely yours,
Mike.