Re: + memory-hotplug-fix-kswapd-looping-forever-problem-fix-fix.patch added to -mm tree

[Minchan Kim <minchan@kernel.org>]

On Thu, Jul 19, 2012 at 09:57:50AM -0700, Tejun Heo wrote:
> Hello,
> 
> On Thu, Jul 19, 2012 at 09:48:45AM +0900, Minchan Kim wrote:
> > > Maybe trigger warning if some fields which have to be zero aren't?
> > 
> > It's not good because this causes adding new WARNING in that part
> > whenever we add new field in pgdat. It nullify this patch's goal.
> 
> Maybe just do that on some fields?  The goal is catching unlikely case
> where archs leave the struct with garbage data.  I don't think full
> coverage is an absolute requirement.  Or reorganize the fields such

IIUC your previous reply, archs can use any fields during boot.
If so, we need full coverage for catching it.

> that fields unused by boot code is collected at the top so that it can
> be memset after certain offset?

If the fields touched by boot are limited, it's good idea.
Let me ask a question.
What fields are used by boot code before calling free_area_init_node
(excpet struct bootmem_data *bdata)?

> 
> But, really, given how the structure is used, I think we're better off
> just making sure all archs clear them and maybe have a sanity check or
> two just in case.  It's not like breakage on that front is gonna be
> subtle.

Of course, it seems all archs seems to zero-out already as I mentioned
(Not sure, MIPS) but Andrew doesn't want it. Andrew?

> 
> Thanks.
> 
> -- 
> tejun
> 
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-- 
Kind regards,
Minchan Kim

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