lkml.org 
[lkml]   [2020]   [Jun]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2] ovl: provide real_file() and overlayfs get_unmapped_area()
On Thu, May 28, 2020 at 11:01 PM Mike Kravetz <mike.kravetz@oracle.com> wrote:
>
> On 5/28/20 1:37 AM, kbuild test robot wrote:
> > Hi Mike,
> >
> > I love your patch! Yet something to improve:
> >
> > [auto build test ERROR on miklos-vfs/overlayfs-next]
> > [also build test ERROR on linus/master v5.7-rc7]
> > [cannot apply to linux/master next-20200526]
> > [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/Mike-Kravetz/ovl-provide-real_file-and-overlayfs-get_unmapped_area/20200528-080533
> > base: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next
> > config: h8300-randconfig-r036-20200528 (attached as .config)
> > compiler: h8300-linux-gcc (GCC) 9.3.0
> > reproduce (this is a W=1 build):
> > 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
> > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=h8300
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kbuild test robot <lkp@intel.com>
> >
> > All error/warnings (new ones prefixed by >>, old ones prefixed by <<):
> >
> > fs/overlayfs/file.c: In function 'ovl_get_unmapped_area':
> >>> fs/overlayfs/file.c:768:14: error: 'struct mm_struct' has no member named 'get_unmapped_area'
> > 768 | current->mm->get_unmapped_area)(realfile,
> > | ^~
> >>> fs/overlayfs/file.c:770:1: warning: control reaches end of non-void function [-Wreturn-type]
> > 770 | }
> > | ^
> >
> > vim +768 fs/overlayfs/file.c
> >
> > 760
> > 761 static unsigned long ovl_get_unmapped_area(struct file *file,
> > 762 unsigned long uaddr, unsigned long len,
> > 763 unsigned long pgoff, unsigned long flags)
> > 764 {
> > 765 struct file *realfile = real_file(file);
> > 766
> > 767 return (realfile->f_op->get_unmapped_area ?:
> > > 768 current->mm->get_unmapped_area)(realfile,
> > 769 uaddr, len, pgoff, flags);
> > > 770 }
> > 771
> >
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> >
>
> Well yuck! get_unmapped_area is not part of mm_struct if !CONFIG_MMU.
>
> Miklos, would adding '#ifdef CONFIG_MMU' around the overlayfs code be too
> ugly for you? Another option is to use real_file() in the mmap code as
> done in [1].

I think the proper fix is to add an inline helper
(call_get_unmapped_area()?) in linux/mm.h, and make that work properly
for the NOMMU case as well.

Thanks,
Miklos

\
 
 \ /
  Last update: 2020-06-04 11:17    [W:0.121 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site