Re: [v2 PATCH] mm: move page_ext_init after all struct pages are initialized

[Shi, Yang]

On 5/20/2016 6:16 AM, Michal Hocko wrote:
> On Thu 19-05-16 15:13:26, Yang Shi wrote:
> [...]
> > diff --git a/init/main.c b/init/main.c
> > index b3c6e36..2075faf 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -606,7 +606,6 @@ asmlinkage __visible void __init start_kernel(void)
> >  		initrd_start = 0;
> >  	}
> >  #endif
> > -	page_ext_init();
> >  	debug_objects_mem_init();
> >  	kmemleak_init();
> >  	setup_per_cpu_pageset();
> > @@ -1004,6 +1003,8 @@ static noinline void __init kernel_init_freeable(void)
> >  	sched_init_smp();
> >
> >  	page_alloc_init_late();
> > +	/* Initialize page ext after all struct pages are initializaed */
> > +	page_ext_init();
> >
> >  	do_basic_setup();
>
> I might be missing something but don't we have the same problem with
> CONFIG_FLATMEM? page_ext_init_flatmem is called way earlier. Or
> CONFIG_DEFERRED_STRUCT_PAGE_INIT is never enabled for CONFIG_FLATMEM?

Yes, CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which 
depends on SPARSEMEM. So, this config is not valid for FLATMEM at all.

Thanks,
Yang

>