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

Andrew Morton
2007-09-14T01:44:56Z

On Tue, 11 Sep 2007 18:37:12 +0900 Yasunori Goto <y-goto@jp.fujitsu.com> wrote:

>
> > > + if (onlined_pages){
> >
> > Nit, needs a space there before the '{'.
>
> Ah, Ok. I attached fixed patch in this mail.
>
> > The problem as I see it is that when we boot the system we start a
> > kswapd on all nodes with memory. If the hot-add adds memory to a
> > pre-existing node with no memory we will not start one and we end up
> > with a node with memory and no kswapd. Bad.
> >
> > As kswapd_run is a no-op when a kswapd already exists this seems a safe
> > way to fix that. Paul's ->zone conversion is obviously correct also.
> >
> > Acked-by: Andy Whitcroft <apw@shadowen.org>
>
> Thanks for your explanation.
> You mentioned all of my intention correctly. :-)
>
>
> ----
>
> Fix kswapd doesn't run when memory is added on memory-less-node.
> Fix compile error of zone->node when CONFIG_NUMA is off.
>
> Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
> Acked-by: Andy Whitcroft <apw@shadowen.org>
>
>
> ---
> mm/memory_hotplug.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> Index: current/mm/memory_hotplug.c
> ===================================================================
> --- current.orig/mm/memory_hotplug.c 2007-09-07 18:08:07.000000000 +0900
> +++ current/mm/memory_hotplug.c 2007-09-11 17:29:19.000000000 +0900
> @@ -211,10 +211,12 @@ int online_pages(unsigned long pfn, unsi
> online_pages_range);
> zone->present_pages += onlined_pages;
> zone->zone_pgdat->node_present_pages += onlined_pages;
> - if (onlined_pages)
> - node_set_state(zone->node, N_HIGH_MEMORY);
>
> setup_per_zone_pages_min();
> + if (onlined_pages) {
> + kswapd_run(zone_to_nid(zone));
> + node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
> + }
>
> if (need_zonelists_rebuild)
> build_all_zonelists();
> @@ -269,9 +271,6 @@ int add_memory(int nid, u64 start, u64 s
> if (!pgdat)
> return -ENOMEM;
> new_pgdat = 1;
> - ret = kswapd_run(nid);
> - if (ret)
> - goto error;
> }
>
> /* 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.