Re: [regression] Boot crash with: f7426b983a6a ("mm: cma: adjust address limit to avoid hitting low/high memory boundary")

[Joonsoo Kim]

On Mon, Dec 08, 2014 at 11:56:40AM +0100, Ingo Molnar wrote:
> 
> * Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
> 
> > On Thu, Nov 27, 2014 at 02:05:56PM +0100, Ingo Molnar wrote:
> > > 
> > > Any replies to this regression after 10 days, or should I send a 
> > > revert patch?
> > 
> > Hello, Ingo.
> > 
> > I can reproduce your problem and find root cause.
> > If CONFIG_DEBUG_VIRTUAL is enabled, __pa() checks whether virtual
> > address is valid or not. Because high_memory is not direct mapped
> > address, error occurs. IMO, physical address of high_memory is
> > useful to check phycal address of highmem boundary so do following
> > workaround to avoid validation is reasonable. But, if there is
> > a better solution, please let me know. I think that Marek will be
> > better than me in this area.
> > 
> > Please check following change to fix your problem.
> > If you agree following change, I will send it to Andrew with
> > proper description.
> > 
> > Thanks.
> > 
> > ------->8-------------
> > diff --git a/mm/cma.c b/mm/cma.c
> > index ee3c3e0..45cd0a6 100644
> > --- a/mm/cma.c
> > +++ b/mm/cma.c
> > @@ -227,7 +227,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
> >  			bool fixed, struct cma **res_cma)
> >  {
> >  	phys_addr_t memblock_end = memblock_end_of_DRAM();
> > -	phys_addr_t highmem_start = __pa(high_memory);
> > +	phys_addr_t highmem_start = __pa_nodebug(high_memory);
> >  	int ret = 0;
> >  
> >  	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
> 
> Looks like this patch solves my boot crash problem:
> 
>   Tested-by: Ingo Molnar <mingo@xxxxxxxxxx>
> 
> I'll let you know if there's any problem left as I test it some 
> more. Consider the bug fixed!
> 

Hello, Andrew.

Could you manage this fix for above boot regression in x86?
Patch itself is so dirty, because __pa_nodebug() is implemented only
in x86. If someone knows better idea, please let me know.

Thanks.

--------------->8------------