Re: [PATCH] mm: add dummy can_do_mlock() helper

[Jason Gunthorpe]

On Tue, Sep 10, 2019 at 09:10:30AM +0200, Michal Hocko wrote:
> On Mon 09-09-19 22:41:40, Arnd Bergmann wrote:
> > On kernels without CONFIG_MMU, we get a link error for the siw
> > driver:
> > 
> > drivers/infiniband/sw/siw/siw_mem.o: In function `siw_umem_get':
> > siw_mem.c:(.text+0x4c8): undefined reference to `can_do_mlock'
> > 
> > This is probably not the only driver that needs the function
> > and could otherwise build correctly without CONFIG_MMU, so
> > add a dummy variant that always returns false.
> > 
> > Fixes: 2251334dcac9 ("rdma/siw: application buffer management")
> > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Makes sense
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> 
> but IB on nonMMU? Whut? Is there any HW that actually supports this?
> Just wondering...

I've never heard of anyone doing this configuration, and I don't
really know much about nommu to comment if it could even potentially
work or not..

Jason