linux-kernel - Re: [PATCH v3] staging: kpc2000: Convert put_page to put_user

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Message-ID: <20190720173615.GA4323@bharath12345-Inspiron-5559>
Date:   Sat, 20 Jul 2019 23:06:15 +0530
From:   Bharath Vedartham <linux.bhar@...il.com>
To:     Matt Sickler <Matt.Sickler@...tronics.com>
Cc:     "jhubbard@...dia.com" <jhubbard@...dia.com>,
        "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "jglisse@...hat.com" <jglisse@...hat.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>
Subject: Re: [PATCH v3] staging: kpc2000: Convert put_page to put_user_page*()

On Fri, Jul 19, 2019 at 08:59:02PM +0000, Matt Sickler wrote:
> >From: Bharath Vedartham <linux.bhar@...il.com>
> >Changes since v2
> >        - Added back PageResevered check as suggested by John Hubbard.
> >
> >The PageReserved check needs a closer look and is not worth messing
> >around with for now.
> >
> >Matt, Could you give any suggestions for testing this patch?
> 
> Myself or someone else from Daktronics would have to do the testing since the
> hardware isn't really commercially available.  I've been toying with the idea
> of asking for a volunteer from the mailing list to help me out with this - I'd
> send them some hardware and they'd do all the development and testing. :)
> I still have to run that idea by Management though.
> 
> >If in-case, you are willing to pick this up to test. Could you
> >apply this patch to this tree and test it with your devices?
> 
> I've been meaning to get to testing the changes to the drivers since upstreaming
> them, but I've been swamped with other development.  I'm keeping an eye on the
> mailing lists, so I'm at least aware of what is coming down the pipe.
> I'm not too worried about this specific change, even though I don't really know
> if the reserved check and the dirtying are even necessary.
> It sounded like John's suggestion was to not do the PageReserved() check and just
> use put_user_pges_dirty() all the time.  John, is that incorrect?
The change is fairly trivial in the upstream kernel. It requires no
testing in the upstream kernel. It would be great if you could test it
on John's git tree with the implemented gup tracking subsystem and check
if gup tracking is working alright with your dma driver. I think this
patch will easily apply to John's git tree.

Thanks!
Bharath