linux-kernel - Re: [PATCH 2/2] mm/gup: fix a misnamed "write" argument: should be "flags"

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Message-ID: <20191014135234.7ak32pfir6du3xae@box>
Date:   Mon, 14 Oct 2019 16:52:34 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     John Hubbard <jhubbard@...dia.com>
Cc:     kbuild test robot <lkp@...el.com>, kbuild-all@...ts.01.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Keith Busch <keith.busch@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 2/2] mm/gup: fix a misnamed "write" argument: should be
 "flags"

On Sun, Oct 13, 2019 at 11:43:10PM -0700, John Hubbard wrote:
> On 10/13/19 11:12 PM, kbuild test robot wrote:
> > Hi John,
> > 
> > Thank you for the patch! Yet something to improve:
> > 
> > [auto build test ERROR on linus/master]
> > [cannot apply to v5.4-rc3 next-20191011]
> > [if your patch is applied to the wrong git tree, please drop us a note to help
> > improve the system. BTW, we also suggest to use '--base' option to specify the
> > base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
> > 
> > url:    https://github.com/0day-ci/linux/commits/John-Hubbard/gup-c-gup_benchmark-c-trivial-fixes-before-the-storm/20191014-114158
> > config: powerpc-defconfig (attached as .config)
> > compiler: powerpc64-linux-gcc (GCC) 7.4.0
> > reproduce:
> >          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >          chmod +x ~/bin/make.cross
> >          # save the attached .config to linux build tree
> >          GCC_VERSION=7.4.0 make.cross ARCH=powerpc
> > 
> > If you fix the issue, kindly add following tag
> > Reported-by: kbuild test robot <lkp@...el.com>
> > 
> > All errors (new ones prefixed by >>):
> > 
> >     mm/gup.c: In function 'gup_hugepte':
> > > > mm/gup.c:1990:33: error: 'write' undeclared (first use in this function); did you mean 'writeq'?
> >       if (!pte_access_permitted(pte, write))
> >                                      ^~~~~
> >                                      writeq
> >     mm/gup.c:1990:33: note: each undeclared identifier is reported only once for each function it appears in
> > 
> 
> OK, so this shows that my cross-compiler test scripts are faulty lately,
> sorry I missed this.
> 
> But more importantly, the above missed case is an example of when "write" really
> means "write", as opposed to meaning flags.
> 
> Please put this patch on hold or drop it, until we hear from the authors as to how
> they would like to resolve this. I suspect it will end up as something like:
> 
> 	bool write = (flags & FOLL_WRITE);
> 
> ...perhaps?

Just use

	if (!pte_access_permitted(pte, flags & FOLL_WRITE))

as we have in gup_pte_range().

And add:

Fixes: cbd34da7dc9a ("mm: move the powerpc hugepd code to mm/gup.c")

-- 
 Kirill A. Shutemov