Re: [PATCH -mm] mm: Fix memory hotplug + sparsemem build.

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

On Thu, 2007-09-13 at 19:41 -0700, Andrew Morton wrote:
> On Fri, 14 Sep 2007 11:02:43 +0900 Yasunori Goto <y-goto@jp.fujitsu.com> wrote:
> 
> > > >  	/* call arch's memory hotadd */
> > > > 
> > > 
> > > OK, we're getting into a mess here.  This patch fixes
> > > update-n_high_memory-node-state-for-memory-hotadd.patch, but which patch
> > > does update-n_high_memory-node-state-for-memory-hotadd.patch fix?
> > > 
> > > At present I just whacked
> > > update-n_high_memory-node-state-for-memory-hotadd.patch at the end of
> > > everything, but that was lazy of me and it ends up making a mess.
> > 
> > It is enough. No more patch is necessary for these issues.
> > I already fixed about Andy-san's comment. :-)
> 
> Now I'm more confused.  I have two separeate questions:
> 
> a) Is the justr-added update-n_high_memory-node-state-for-memory-hotadd-fix.patch
>    still needed?
> 
> b) Which patch in 2.6.22-rc4-mm1 does
>    update-n_high_memory-node-state-for-memory-hotadd.patch fix?  In other
>    words, into which patch should I fold
>    update-n_high_memory-node-state-for-memory-hotadd.patch prior to sending
>    to Linus?

Andrew:  

I originally sent in the "update-n_high_memory..." patch against
23-rc3-mm1 on 27aug to fix a problem that I introduced when I moved the
populating of N_HIGH_MEMORY state to free_area_init_nodes().  This would
miss setting the "has memory" node state for hot added memory.  I never
saw any response, but then it ended up in 23-rc4-mm1.

This Tuesday, Paul Mundt sent in a patch to fix a build problem with
MEMORY_HOTPLUG_SPARSE introduced by my patch.  He replaced zone->node
with zone_to_nid(zone) in the node_set_state() arguments.

The latest patch, from Yasunori-san, I believe, starts kswapd for nodes
to which memory has been hot-added.  As I understand it, his is needed
because the memoryless nodes patch results in no kswapd for memoryless
nodes.

Does that help?

Lee


> 
>    (I (usually) get to work this out for myself.  Sometimes it is painful).
> 
> Generally, if people tell me which patch-in-mm their patch is fixing,
> it really helps.  Adrian does this all the time.
> 
> Thanks.
> 
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