Re: [mmotm:master 140/321] fs/built-in.o:undefined reference to `filemap_page_mkwrite'

[Oleg Nesterov <oleg@redhat.com>]

On 07/16, Benjamin LaHaise wrote:
>
> On Thu, Jul 16, 2015 at 09:38:56PM +0200, Oleg Nesterov wrote:
> > On 07/16, Benjamin LaHaise wrote:
> > >
> > > On Thu, Jul 16, 2015 at 09:05:03PM +0200, Oleg Nesterov wrote:
> > > > Thanks!
> > > ...
> > > > but the problem looks clear: CONFIG_MMU is not set, so we need
> > > > a dummy filemap_page_mkwrite() along with generic_file_mmap() and
> > > > generic_file_readonly_mmap().
> > > >
> > > > I'll send the fix, but...
> > > >
> > > > Benjamin, Jeff, shouldn't AIO depend on MMU? Or it can actually work even
> > > > if CONFIG_MMU=n?
> > >
> > > It should work when CONFIG_MMU=n,
> >
> > Really? I am just curious.
>
> I am not saying the code currently does, but that the use of the functionality
> is valid.  The code clearly doesn't at the moment, and given that nobody
> has complained, it's seems unlikely that there are any active users.

Hmm. Confused...

So sys_io_setup() can't succed if CONFIG_MMU=n.

Then why do we allow CONFIG_AIO=y in this case? And it is even
"default y" and needs EXPERT to disable...

But OK, I won't argue. I'll send the fix which fixes the build.

Thanks!

Oleg.

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