On Wed, Sep 21, 2016 at 12:39:51PM +0530, Aneesh Kumar K.V wrote:
What I was checking was how will one mark a node movable in ppc64 ? I
don't see ppc64 code doing the equivalent of memblock_mark_hotplug().
Post boot, the marking mechanism is not necessary. You can create a
movable node by putting all of the node's memory into ZONE_MOVABLE
during the hotplug.
So when you say "Onlining memory into ZONE_MOVABLE requires
CONFIG_MOVABLE_NODE" where is that restriction ?. IIUC,
should_add_memory_movable() will only return ZONE_MOVABLE only if it is
non empty and MOVABLE_NODE will create a ZONE_MOVABLE zone by default
only if it finds a memblock marked hotpluggable. So wondering if we
are not calling memblock_mark_hotplug() how is it working. Or am I
missing something ?
You are looking at the addition step of hotplug. You're correct there,
the memory is added to the default zone, not ZONE_MOVABLE. The
transition to ZONE_MOVABLE takes place during the onlining step. In
online_pages():
zone = move_pfn_range(zone_shift, pfn, pfn + nr_pages);
The reason we need CONFIG_MOVABLE_NODE is right before that:
if ((zone_idx(zone) > ZONE_NORMAL ||
online_type == MMOP_ONLINE_MOVABLE) &&
!can_online_high_movable(zone))
return -EINVAL;
where can_online_high_movable() is defined like this:
#ifdef CONFIG_MOVABLE_NODE
/*
* When CONFIG_MOVABLE_NODE, we permit onlining of a node which doesn't have
* normal memory.
*/
static bool can_online_high_movable(struct zone *zone)
{
return true;
}
#else /* CONFIG_MOVABLE_NODE */
/* ensure every online node has NORMAL memory */
static bool can_online_high_movable(struct zone *zone)
{
return node_state(zone_to_nid(zone), N_NORMAL_MEMORY);
}
#endif /* CONFIG_MOVABLE_NODE */
To be more clear, I can change the commit log to say "Onlining all of a
node's memory into ZONE_MOVABLE requires CONFIG_MOVABLE_NODE".
--
Reza Arbab
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