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Date:   Sun, 19 Jun 2022 17:19:59 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     kernel test robot <lkp@intel.com>, kbuild-all@lists.01.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [viro-vfs:work.iov_iter_get_pages 24/33] lib/iov_iter.c:1295
 iter_xarray_get_pages() warn: unsigned 'count' is never less than zero.
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On Sun, Jun 19, 2022 at 04:54:57PM +0100, Matthew Wilcox wrote:
> On Sun, Jun 19, 2022 at 04:48:54PM +0100, Al Viro wrote:
> > On Sun, Jun 19, 2022 at 11:40:37PM +0800, kernel test robot wrote:
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git work.iov_iter_get_pages
> > > head:   fe8e2809c7db0ec65403b31b50906f3f481a9b10
> > > commit: e64d637d648390e4ac0643747ae174c3be15f243 [24/33] iov_iter: saner helper for page array allocation
> > > config: mips-randconfig-m031-20220619 (https://download.01.org/0day-ci/archive/20220619/202206192306.POJg04ej-lkp@intel.com/config)
> > > compiler: mips-linux-gcc (GCC) 11.3.0
> > > 
> > > If you fix the issue, kindly add following tag where applicable
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > 
> > > smatch warnings:
> > > lib/iov_iter.c:1295 iter_xarray_get_pages() warn: unsigned 'count' is never less than zero.
> > 
> > Joy...  Should've been int all along, obviously (pgoff_t for number of array
> > elements?)
> 
> I've been using 'long' for that just because I don't want the drama of
> "we need to support 16GB pages" to have anything to do with me.

That's "kvmalloc a flat array with that many pointers to pages in it and
and pin those suckers"...